3512C Engines for 785C Off-Highway Trucks with Dynamic Gas Blending Caterpillar

Sensor Signal (Analog, Active) - Test - In Cylinder Pressure Sensor

Usage:

3512 8BR

Use this procedure to troubleshoot a problem with a sensor. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
6161-2 Engine Cylinder 1 Pressure : Erratic, Intermittent, or Incorrect	4805-2 Engine Cylinder #1 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the Electronic Control Module (ECM) to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the In Cylinder Pressure Sensor (ICPS) ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6161-3 Engine Cylinder 1 Pressure : Voltage Above Normal	4805-3 Engine Cylinder #1 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6161-4 Engine Cylinder 1 Pressure : Voltage Below Normal	4805-4 Engine Cylinder #1 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6161-20 Engine Cylinder 1 Pressure : Data Drifted High	4805-20 Engine Cylinder #1 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6161-21 Engine Cylinder 1 Pressure : Data Drifted Low	4805-21 Engine Cylinder #1 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6162-2 Engine Cylinder 2 Pressure : Erratic, Intermittent, or Incorrect	4806-2 Engine Cylinder #2 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6162-3 Engine Cylinder 2 Pressure : Voltage Above Normal	4806-3 Engine Cylinder #2 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6162-4 Engine Cylinder 2 Pressure : Voltage Below Normal	4806-4 Engine Cylinder #2 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6162-20 Engine Cylinder 2 Pressure : Data Drifted High	4806-20 Engine Cylinder #2 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6162-21 Engine Cylinder 2 Pressure : Data Drifted Low	4806-21 Engine Cylinder #2 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6163-2 Engine Cylinder 3 Pressure : Erratic, Intermittent, or Incorrect	4807-2 Engine Cylinder #3 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6163-3 Engine Cylinder 3 Pressure : Voltage Above Normal	4807-3 Engine Cylinder #3 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6163-4 Engine Cylinder 3 Pressure : Voltage Below Normal	4807-4 Engine Cylinder #3 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6163-20 Engine Cylinder 3 Pressure : Data Drifted High	4807-20 Engine Cylinder #3 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6163-21 Engine Cylinder 3 Pressure : Data Drifted Low	4807-21 Engine Cylinder #3 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6164-2 Engine Cylinder 4 Pressure : Erratic, Intermittent, or Incorrect	4808-2 Engine Cylinder #4 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6164-3 Engine Cylinder 4 Pressure : Voltage Above Normal	4808-3 Engine Cylinder #4 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6164-4 Engine Cylinder 4 Pressure : Voltage Below Normal	4808-4 Engine Cylinder #4 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6164-20 Engine Cylinder 4 Pressure : Data Drifted High	4808-20 Engine Cylinder #4 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6164-21 Engine Cylinder 4 Pressure : Data Drifted Low	4808-21 Engine Cylinder #4 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6165-2 Engine Cylinder 5 Pressure : Erratic, Intermittent, or Incorrect	4809-2 Engine Cylinder #5 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6165-3 Engine Cylinder 5 Pressure : Voltage Above Normal	4809-3 Engine Cylinder #5 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6165-4 Engine Cylinder 5 Pressure : Voltage Below Normal	4809-4 Engine Cylinder #5 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6165-20 Engine Cylinder 5 Pressure : Data Drifted High	4809-20 Engine Cylinder #5 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6165-21 Engine Cylinder 5 Pressure : Data Drifted Low	4809-21 Engine Cylinder #5 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6166-2 Engine Cylinder 6 Pressure : Erratic, Intermittent, or Incorrect	4810-2 Engine Cylinder #6 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6166-3 Engine Cylinder 6 Pressure : Voltage Above Normal	4810-3 Engine Cylinder #6 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6166-4 Engine Cylinder 6 Pressure : Voltage Below Normal	4810-4 Engine Cylinder #6 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6166-20 Engine Cylinder 6 Pressure : Data Drifted High	4810-20 Engine Cylinder #6 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6166-21 Engine Cylinder 6 Pressure : Data Drifted Low	4810-21 Engine Cylinder #6 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6167-2 Engine Cylinder 7 Pressure : Erratic, Intermittent, or Incorrect	4811-2 Engine Cylinder #7 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6167-3 Engine Cylinder 7 Pressure : Voltage Above Normal	4811-3 Engine Cylinder #7 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6167-4 Engine Cylinder 7 Pressure : Voltage Below Normal	4811-4 Engine Cylinder #7 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6167-20 Engine Cylinder 7 Pressure : Data Drifted High	4811-20 Engine Cylinder #7 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6167-21 Engine Cylinder 7 Pressure : Data Drifted Low	4811-21 Engine Cylinder #7 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6168-2 Engine Cylinder 8 Pressure : Erratic, Intermittent, or Incorrect	4812-2 Engine Cylinder #8 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6168-3 Engine Cylinder 8 Pressure : Voltage Above Normal	4812-3 Engine Cylinder #8 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6168-4 Engine Cylinder 8 Pressure : Voltage Below Normal	4812-4 Engine Cylinder #8 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6168-20 Engine Cylinder 8 Pressure : Data Drifted High	4812-20 Engine Cylinder #8 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6168-21 Engine Cylinder 8 Pressure : Data Drifted Low	4812-21 Engine Cylinder #8 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6169-2 Engine Cylinder 9 Pressure : Erratic, Intermittent, or Incorrect	4813-2 Engine Cylinder #9 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6169-3 Engine Cylinder 9 Pressure : Voltage Above Normal	4813-3 Engine Cylinder #9 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6169-4 Engine Cylinder 9 Pressure : Voltage Below Normal	4813-4 Engine Cylinder #9 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6169-20 Engine Cylinder 9 Pressure : Data Drifted High	4813-20 Engine Cylinder #9 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6169-21 Engine Cylinder 9 Pressure : Data Drifted Low	4813-21 Engine Cylinder #9 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6170-2 Engine Cylinder 10 Pressure : Erratic, Intermittent, or Incorrect	4814-2 Engine Cylinder #10 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6170-3 Engine Cylinder 10 Pressure : Voltage Above Normal	4814-3 Engine Cylinder #10 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6170-4 Engine Cylinder 10 Pressure : Voltage Below Normal	4814-4 Engine Cylinder #10 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6170-20 Engine Cylinder 10 Pressure : Data Drifted High	4814-20 Engine Cylinder #10 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6170-21 Engine Cylinder 10 Pressure : Data Drifted Low	4814-21 Engine Cylinder #10 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6171-2 Engine Cylinder 11 Pressure : Erratic, Intermittent, or Incorrect	4815-2 Engine Cylinder #11 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6171-3 Engine Cylinder 11 Pressure : Voltage Above Normal	4815-3 Engine Cylinder #11 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6171-4 Engine Cylinder 11 Pressure : Voltage Below Normal	4815-4 Engine Cylinder #11 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6171-20 Engine Cylinder 11 Pressure : Data Drifted High	4815-20 Engine Cylinder #11 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6171-21 Engine Cylinder 11 Pressure : Data Drifted Low	4815-21 Engine Cylinder #11 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6172-2 Engine Cylinder 12 Pressure : Erratic, Intermittent, or Incorrect	4816-2 Engine Cylinder #12 Pressure Sensor : Erratic, Intermittent, or Incorrect	The sensor signal is detected by the ECM to have unstable voltage which exceeds requirements for clean signal processing. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6172-3 Engine Cylinder 12 Pressure : Voltage Above Normal	4816-3 Engine Cylinder #12 Pressure Sensor : Voltage Above Normal	The sensor signal is detected by the ECM to have a voltage above 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6172-4 Engine Cylinder 12 Pressure : Voltage Below Normal	4816-4 Engine Cylinder #12 Pressure Sensor : Voltage Below Normal	The sensor signal is detected by the ECM to have a below 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6172-20 Engine Cylinder 12 Pressure : Data Drifted High	4816-20 Engine Cylinder #12 Pressure Sensor : Data Drifted High	The sensor signal is detected by the ECM to have a voltage above the valid range upper limit 4.6 VDC, but below 4.8 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.
6172-21 Engine Cylinder 12 Pressure : Data Drifted Low	4816-21 Engine Cylinder #12 Pressure Sensor : Data Drifted Low	The sensor signal is detected by the ECM to have a voltage below the valid range upper limit 0.325 VDC, but above 0.1625 VDC. The code is persistently active until the ICPS ECM detects conditions which are no longer abnormal. The code is logged once returned to a normal circuit health or operating condition.

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Illustration 1	g06163715

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® Electronic Technician (ET) to the service tool connector. B. Determine if a code is active or logged.	Codes	Result: An associated code is active. Repair: Troubleshoot any associated codes before continuing with this test. Result: A -2, -3, -4, -20, -21 code is active or logged Proceed to Test Step 2.
2. Inspect the Electrical Connectors and the Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information. C. Perform a 45 N (10 lb) pull test on the connector wires. D. Check the harness for abrasions and pinch points.	Connectors and Wiring	Result: The connectors and wiring appear to be OK. - A -2 code is active or logged. Proceed to Test Step 9. - A -3 code is active or logged. Proceed to Test Step 3. - A -4 code is active or logged. Proceed to Test Step 7. - A -20 or -21 code is active or logged. Proceed to Test Step 4. Result: There is a problem with the connectors and/or wiring. Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminated the problem.
3. Create a Short at the ICPS Sensor Adapter Harness Connector A. Turn the keyswitch to the OFF position. B. Disconnect the Electronic Control Module (ECM) main harness from the In Cylinder Pressure Sensor (ICPS) adapter harness at the 3-pin Ampseal connector. C. Install the jumper wire between the following terminals at the sensor connector: - Terminal 2 (sensor return) and Terminal 3 (signal) D. Connect Cat ET. E. Use Cat ET to monitor the following: - -4 code F. Turn the keyswitch to the OFF position.	Create a Short	Result: A -4 code became active. Proceed to Test Step 6. Result: A -4 code did not become active. The ECM did not detect the short circuit. There is an open circuit in the main wiring harness between the ECM and the Ampseal connector at the adapter harness. Repair: Repair or replace the main wiring harness. Verify that the repair eliminated the problem.
4. Measure the Resistance of the Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the J2/P2 connector from the ICPS ECM. C. Disconnect the main wiring harness from the ICPS adapter harness at the 3-pin Ampseal connector. D. Measure the resistance between the following pins: - Terminal 2 (sensor return) and the appropriate pin for that sensor on the P2 connector. - Terminal 3 (sensor signal) and the appropriate pin for that sensor on the P2 connector.	Resistance	Result: There were less than 10 ohms of resistance measured between the Ampseal terminal and the terminal at the P2 ICPS ECM connector. Proceed to Test Step 5. Result: There were more than 10 ohms of resistance measured between the Ampseal terminal and the terminal at the P2 ICPS ECM connector. Repair: There is an open or high resistance on the circuit that is affecting the signal accuracy. Repair or replace the main wiring harness. Verify that the repair eliminated the problem.
5. Check the Sensor Circuit for a Pin to Pin Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the J2/P2 connector from the ICPS ECM. C. Disconnect the main wiring harness from the ICPS adapter harness at the 3-pin Ampseal connector. D. Measure the resistance between the following pins: - The affected ICPS return wire pin and all ECM connector pins. - The affected ICPS signal wire pin and all ECM connector pins.	Short Circuit	Result: There were more than 100 K ohms of resistance between the affected ICPS signal wire or ground wire pin and all other pins in the ICPS ECM connector. Proceed to Test Step 6. Result: There were less than 100 K ohms of resistance between the affected ICPS signal wire or ground wire pin and all other pins in the ICPS ECM connector. Repair: There is a short in the main wiring harness. Repair or replace the main wiring harness. Verify that the repair eliminated the problem.
6. Exchange the ICPS Adapter Wiring Harness A. Turn the keyswitch to the OFF position. B. Temporarily exchange the affected ICPS adapter wiring harness with a known good adapter wiring harness from a functioning ICPS. Note: Use caution when disconnecting the Hirschmann connector from the ICPS. Do not remove connector by pulling on the adapter harness wires. C. Turn the keyswitch to the ON position. D. Connect Cat ET. E. Use Cat ET to monitor the following: - Codes	Wiring Harness	Result: The active code does not appear on the affected ICPS circuit with the known good adapter wiring harness installed. The previously active code is now active on the cylinder that received the suspect harness. Repair: Replace the ICPS adapter wiring harness. Verify that the repair eliminated the problem. Result: The active code remains active on the affected ICPS circuit with the known good adapter wiring harness installed. Repair: The ICPS has an open or failed circuit. Replace the ICPS. Verify that the repair eliminated the problem.
7. Create an Open at the ICPS Adapter Harness Connector A. Turn the keyswitch to the OFF position. B. Disconnect the ECM main harness from the ICPS adapter harness at the 3-pin Ampseal connector. C. Connect Cat ET. D. Use Cat ET to monitor the following: - -3 code E. Turn the keyswitch to the OFF position.	Create an Open	Result: A -3 code became active. Proceed to Test Step 8. Result: A -3 code did not become active. Repair: There is a short to ground in the main wiring harness. Repair or replace the main wiring harness. Verify that the repair eliminated the problem.
8. Create an Open at the ICPS Connector A. Turn the keyswitch to the OFF position. B. Disconnect the sensor with the active -4 code. Note: Use caution when disconnecting the Hirschmann connector from the ICPS. Do not remove connector by pulling on the adapter harness wires. C. Connect Cat ET. D. Use Cat ET to monitor the following: - -3 code E. Turn the keyswitch to the OFF position.	Create an Open	Result: A -3 code became active. Repair: Replace the ICPS. Verify that the repair eliminated the problem. Result: A -3 code did not become active. Repair: There is a short to ground on the ICPS adapter wiring harness. Repair or replace the adapter wiring harness. Verify that the repair eliminated the problem.
9. Exchange the ICPS Adapter Wiring Harness A. Turn the keyswitch to the OFF position. B. Temporarily exchange the affected ICPS adapter wiring harness with a known good adapter wiring harness from a functioning ICPS. Note: Use caution when disconnecting the Hirschmann connector from the ICPS. Do not remove connector by pulling on the adapter harness wires. C. Turn the keyswitch to the ON position. D. Connect Cat ET. E. Use Cat ET to monitor the following: - Codes	Wiring Harness	Result: The active code does not appear on the affected ICPS circuit with the known good adapter wiring harness installed. Repair: Replace the ICPS adapter wiring harness. Verify that the repair eliminated the problem. Result: The active code remains active on the affected ICPS circuit with the known good adapter wiring harness installed. Proceed to Test Step 10.
10. Check the Main Wiring Harness for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the J2/P2 connector from the ICPS ECM. C. Disconnect the main wiring harness from the ICPS adapter harness at the 3-pin Ampseal connector. D. Measure the resistance between the following locations for the sensor: - The signal wire on the ICPS ECM terminals and the terminal on the main wiring harness Ampseal ICPS connector. - The ground wire on the ICPS ECM terminals and the terminal on the main wiring harness Ampseal ICPS connector.	Open Circuit	Result: There were less than 10 Ohms of resistance. Proceed to Test Step 11. Result: There were more than 10 Ohms of resistance. Repair: An open circuit or high resistance from a damaged wire has been detected. Repair or replace the main wiring harness. If the problem is not resolved, proceed to Test Step 11.
11. Check the Main Wiring Harness for a Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the J2/P2 connector from the ICPS ECM. C. Disconnect the main wiring harness from the ICPS adapter harness at the 3-pin Ampseal connector. D. Measure the resistance between the following locations for the sensor: - The ICPS ECM terminal or the terminal at the main harness Ampseal ICPS connector and Engine ground.	Short Circuit	Result: There were more than 100 K Ohms of resistance measured between the terminal and engine ground. Proceed to Test Step 12. Result: There were less than 100 K Ohms of resistance measured between the terminal and engine ground. Repair: A short circuit to ground has been detected. Repair or replace the main wiring harness. If the problem is not resolved, proceed to Test Step 12.
12. Check the Sensor Circuit for a Pin to Pin Short Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the J2/P2 connector from the ICPS ECM. C. Disconnect the main wiring harness from the ICPS adapter harness at the 3-pin Ampseal connector. D. Measure the resistance between the following locations for the sensor: - The affected ICPS signal wire pin and all ICPS ECM connector pins. - The affected ICPS ground wire pin and all ICPS ECM connector pins.	Short Circuit	Result: There were more than 100 K Ohms of resistance between the affected ICPS signal wire or ground wire pin and all other pins in the ECM connector. Proceed to Test Step 13. Result: There were less than 100 K Ohms of resistance between the affected ICPS signal wire or ground wire pin and all other pins in the ECM connector. Repair: There is a short circuit in the main wiring harness. Repair or replace the main wiring harness. If the problem is not resolved, proceed to Test Step 13.
13. Exchange the ICPS A. Turn the keyswitch to the OFF position. B. Temporarily exchange the affected ICPS with a known good ICPS from a functioning ICPS circuit. C. Turn the keyswitch to the ON position. D. Start the engine. E. Connect Cat ET. F. Use Cat ET to monitor the following: - Codes	Sensor	Result: The active code has moved with the affected ICPS and the active code does not appear on the previously affected ICPS circuit. Repair: Replace the ICPS. Verify that the repair eliminated the problem. Result: The active code remains active on the original faulty ICPS circuit. Proceed to Test Step 14.
14. Check all Engine and Alternator Ground Wires A. Verify that all the ground wires for the engine, alternator, and any other system grounds are clean and have good connections. B. To help with locating the source of electrical noise, Refer to Systems Operation, Grounding Practices for additional information.	Connectors and Wiring	Result: A ground wire was found loose. Repair: Repair or replace damage ground straps or wires. Verify that the repair eliminated the problem. Result: A ground wire problem was not found. Repair: Excessive electrical noise may still be present. Further investigation may be required. Verify that the repair eliminated the problem.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).