C9.3 Tier 4 Final Engines Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the sensors. Also use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.

Table 1

Diagnostic Trouble Codes
J1939 Code	CDL Code	Code Description	Comments
100-3	100-3	Engine Oil Pressure Sensor : Voltage Above Normal	The Electronic Control Module (ECM) detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
100-4	100-4	Engine Oil Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
101-3	101-3	Crankcase Air Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
101-4	101-4	Crankcase Air Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
108-3	3528-3	Atmospheric Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
108-4	3528-4	Atmospheric Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
157-3	1797-3	Fuel Rail Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
157-4	1797-4	Fuel Rail Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
411-3	3387-3	Engine Exhaust Gas Recirculation Differential Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
411-4	3387-4	Engine Exhaust Gas Recirculation Differential Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
1176-3	2738-3	Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
1176-4	2738-4	Turbocharger #1 Compressor Inlet Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
1387-3	1835-3	Auxiliary Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
1387-4	1835-4	Auxiliary Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
2948-3	1924-3	Engine Intake Valve Actuation System Oil Pressure : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
2948-4	1924-4	Engine Intake Valve Actuation System Oil Pressure : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3241-3	3485-3	Aftertreatment #1 Exhaust Gas Temperature #1 Sensor : Voltage Above Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
3241-4	3485-4	Aftertreatment #1 Exhaust Gas Temperature #1 Sensor : Voltage Below Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
3242-3	2452-3	DPF #1 Intake Temperature Sensor : Voltage Above Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
3242-4	2452-4	DPF #1 Intake Temperature Sensor : Voltage Below Normal	The code is logged. The ECM detects voltage that is not in the acceptable range.
3251-2	2458-2	DPF #1 Differential Pressure Sensor : Erratic, Intermittent, or Incorrect	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3251-3	2458-3	DPF #1 Differential Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3251-4	2458-4	DPF #1 Differential Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3358-3	3385-3	EGR Intake Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3385-4	3385-4	EGR Intake Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3480-3	2460-3	ARD Fuel Pressure #1 Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3480-4	2460-4	ARD Fuel Pressure #1 Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3563-3	1785-3	Intake Manifold Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3563-4	1785-4	Intake Manifold Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3609-3	3464-3	DPF #1 Intake Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3609-4	3464-4	DPF #1 Intake Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3837-3	3493-3	Aftertreatment #1 Secondary Air Pressure Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
3837-4	3493-4	Aftertreatment #1 Secondary Air Pressure Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
4077-3	2497-3	ARD Fuel Pressure #2 Sensor : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
4077-4	2497-4	ARD Fuel Pressure #2 Sensor : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
4360-3	3105-3	Aftertreatment #1 SCR Catalyst Intake Gas Temperature : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
4360-4	3105-4	Aftertreatment #1 SCR Catalyst Intake Gas Temperature : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5578-3	289-3	Fuel Pressure Sensor - Before Fuel Filter : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
5578-4	289-4	Fuel Pressure Sensor - Before Fuel Filter : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
5580-3	460-3	Fuel Pressure Sensor - After Fuel Filter : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
5580-4	460-4	Fuel Pressure Sensor - After Fuel Filter : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged. The value of the parameter is set to a gauge pressure.
5708–3	N/A	Engine Coolant Pressure #2 : Voltage Above Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.
5708–4	N/A	Engine Coolant Pressure #2 : Voltage Below Normal	The ECM detects signal voltage that is not in the acceptable range. The code is logged.

The supply voltage is routed to terminal 1 of each sensor connector. The sensor return is routed to terminal 2 of each sensor connector. The sensor signal is routed to terminal 3 of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.

Diagnostics on the Caterpillar Electronic Technician (ET)

Wiggle Test - The Wiggle Test allows you to monitor the status of the signals from the sensors.

For additional information regarding the Wiggle Test, refer to the documentation that accompanies the Cat ET software.

Illustration 1	g03322791

Note: The diagram above is a simplified schematic of the electrical circuit. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic for the complete schematic.

Illustration 2	g03319642

Locations of the sensors and the sensor connectors

Illustration 3	g03771513
(1) Fuel rail pressure sensor

Illustration 4	g03771536
(2) Intake manifold pressure sensor

Illustration 5	g03771539
(3) NRS differential pressure sensor (4) NRS absolute pressure sensor

Illustration 6	g03771577
(5) Atmospheric pressure sensor

Illustration 7	g03771581
(6) Crankcase pressure sensor

Illustration 8	g03771586
(7) Oil pressure sensor

Illustration 9	g03771618
(8) Fuel pressure sensor at the inlet of the tertiary filter (9) Fuel pressure sensor at the outlet of the tertiary filter

Illustration 10	g03771638
CEM (typical) (10) Absolute pressure sensor for the DPF

Illustration 11	g03771663
CEM (typical) (11) Combustion air absolute pressure sensor (12) Main fuel pressure sensor (13) Pilot fuel pressure sensor

Complete the procedure in the order in which the steps are listed.

Table 2

Troubleshooting Test Steps	Values	Results
1. Check for Diagnostic Codes A. Establish communication between Cat® Electronic Technician (ET) and the ECM . Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Turn the keyswitch to the ON position. C. Look for a -3, or -4 active or logged codes:	Diagnostic Code	Result: A -3 diagnostic code is active. Proceed to Test Step 2. Result: A -4 diagnostic code is active. Proceed to Test Step 3. Result: A 2458-2 or 3251-2 diagnostic code is active. Proceed to Test Step 6.
2. Create a Short at the Sensor Connector A. Use a jumper wire in order to create a short between terminal 3 (signal) and terminal 2 (sensor return) at the sensor connector. B. Turn the keyswitch to the ON position. C. Monitor the diagnostic codes on Cat ET. Check for an active -4 diagnostic code for the suspect sensor. D. Turn the keyswitch to the OFF position.	Short Created	Result: A -4 diagnostic code became active after creating the short at the sensor connector. Repair: The wiring is OK. Replace the sensor. Verify that the problem is resolved. Result: A -4 diagnostic code does not become active for the suspect sensor. Proceed to Test Step 4.
3. Create an Open at the Suspect Sensor Connector A. Turn the keyswitch to the OFF position. B. Disconnect the sensor connector of the suspect sensor with the active -4 diagnostic code. C. Turn the keyswitch to the ON position. D. Monitor the diagnostic codes on Cat ET. Check for an active -3 diagnostic code for the suspect sensor. E. Turn the keyswitch to the OFF position.	Create an Open	Result: A -3 diagnostic code became active after disconnecting the sensor. Repair: The wiring is OK. Replace the sensor. Verify that the problem is resolved. Result: A -3 diagnostic code did not became active after disconnecting the sensor. Proceed to Test Step 4.
4. Check the 5 VDC Supply Voltage at the Sensor Connector A. Turn the keyswitch to the ON position. B. Measure the voltage between pin 1 and pin 2 at the suspect sensor.	Test Passed	Result: The supply voltage is approximately 5.0 ± 0.2 VDC Connect the sensor and then proceed to Test Step 5 Result: The supply voltage is not approximately 5.0 ± 0.2 VDC. Repair: There is a short in the harness to the battery. Repair the wiring or replace the harness Verify that the problem is resolved.
5. Perform the Wiggle Test Carefully following this procedure is the best way to identify the root cause of an intermittent problem. A. Turn the keyswitch to the ON position. B. Use CAT ET to run the "Wiggle Test". C. Slowly wiggle the wiring and the connectors between the P2 connector and the sensor. Pay particular attention to the wiring near each connector. Be sure to wiggle all of the wiring. As you wiggle the wiring look for these problems. 1. Loose connectors or damaged connectors 2. Moisture on the connectors or the wiring 3. Damaged that is caused by excessive heat 4. Damage that is caused by chafing 5. Improper routing of wiring 6. Damaged insulation	Test Passed	Result: The wiring failed the Wiggle Test. Repair: There is a problem with the wiring. Repair the wiring or replace the wiring. Verify that the problem is resolved. Result: The wiring passed the Wiggle Test. The problem may be intermittent. Inspect the wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect". If the wiring looks OK perform the following procedure. 1. Turn the keyswitch to the OFF position. 2. Disconnect the connectors. Carefully inspect the terminals for proper installation. Make sure that each terminal is clean and dry. 3. Insert a pin into each socket. Verify that each socket grips the pin firmly. Repair any problems. 4. Connect all connectors. 5. Verify that the problem is resolved. 6. Return the unit to service.

Illustration 12	g03771698
(14) Differential pressure lines

Table 3

Troubleshooting Test Steps	Values	Results
6. Inspect the DPF Differential Pressure Lines, Fittings, and Manifold A. Ensure that the DPF differential pressure lines are connected. B. Ensure that the DPF differential pressure lines, fittings, and manifold are free from obstructions. Make sure that moisture has not frozen in the lines, fittings, and manifold. Note: The 2458-2 or 3251-2 will not activate for several hours if the ambient temperature is below 7° C (45° F) or if an active regeneration has not been performed. If troubleshooting a 2458-2 or 3251-2 and ambient temperature is below 7° C (45° F), perform a "Manual DPF regeneration" after completing the repair to verify that the problem has been resolved.	Lines Inspected	Result: The DPF differential pressure lines, fittings, and manifold are connected and free from obstructions. Proceed to Test Step 7 Result: The DPF differential pressure lines are not connected or the lines, fittings, and manifold have obstructions. Repair: Repair or replace the DPF differential pressure line. Clear all codes. Return the engine to service.
7. Inspect the Electrical Connectors for the ARD Pilot Fuel Pressure Sensor and the DPF Differential Pressure Sensor A. Check the connectors for the differential pressure sensor and the pilot fuel pressure sensor to ensure that the connectors are connected to the proper sensor. Note: The 2458-2 or 3251-2 will not activate for several hours if the ambient temperature is below 7° C (45° F) or if an active regeneration has not been performed. If troubleshooting a 2458-2 or 3251-2 and ambient temperature is below 7° C (45° F), perform a "Manual DPF regeneration" after completing the repair to verify that the problem has been resolved.	Connectors Inspected	Result: A 2458-2 or 3251-2 diagnostic code will appear when the connectors are switched between sensors, be certain the connectors are connected to the correct sensors. Repair: Connect the connectors to the correct sensors. Verify that the problem is resolved. Clear all codes. Return the engine to service.