C15 On-highway Engines Caterpillar

Use this procedure to troubleshoot the system if any of the following diagnostic codes are active or easily repeated:

• 212-03 5 Volt Sensor Supply #1 voltage high

• 212-04 5 Volt Sensor Supply #1 voltage low

• 232-03 5 Volt Supply voltage high

• 232-04 5 Volt Supply voltage low

Also, use this procedure to troubleshoot the system when you have been directed here by another troubleshooting procedure.

The following background information is related to this procedure:

The Engine Control Module (ECM) supplies the following sensors with regulated 5 VDC:

• Atmospheric pressure sensor

• Intake manifold pressure (Boost)

• Engine oil pressure sensor

• Pressure sensor for the intake valve actuation pressure

The 5 volt sensor supply provides power to all 5 volt sensors. The ECM supplies 5.0 ± 0.16 VDC to terminal A of each sensor connector. The sensor common from the ECM connector goes to terminal B of each sensor connector. The sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the ECM.

Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If the -03 code is logged, it is possible that all of the sensors have been damaged. Repair the sensor supply and check for any "ACTIVE" sensor diagnostic codes in order to determine if a sensor has failed.

Illustration 1	g01098596

Illustration 2	g01098563
P2 ECM connector (P2-15) Signal for the intake manifold pressure (Boost) (P2-17) Sensor common (P2-28) Signal for the engine oil pressure (P2-54) Pressure sensor common (actuator) (P2-57) Signal for the atmospheric pressure (P2-72) +5 Volt sensor supply (P2-74) Signal for the intake valve actuation pressure (P2-80) +5 Volt sensor supply (actuator)

Illustration 3	g01103785
Sensor locations on the left side (1) Intake manifold pressure sensor (Boost) (2) Atmospheric pressure sensor (3) Engine oil pressure sensor

Illustration 4	g01103786
Sensor locations on the right side (4) Pressure sensor for the intake valve actuator

Illustration 5	g01094844
Sensor connector

Test Step 1. INSPECT ELECTRICAL CONNECTORS AND WIRING

1. Turn the keyswitch to the OFF position.

2. Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.

   Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.

4. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

5. Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM.

Expected Result:

All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.

Results:

• OK - The harness and connectors appear to be OK. Proceed to Test Step 2.

• Not OK - There is a problem with the connectors and/or wiring.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.

  Verify that the repair eliminates the problem.

  STOP

Test Step 2. CHECK FOR ACTIVE DIAGNOSTIC CODES

1. Connect the Caterpillar Electronic Technician (ET) to the service tool connector.

2. Turn the keyswitch to the ON position.

3. Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

Expected Result:

There is an active -03 or -04 diagnostic code.

Results:

• OK - A -03 diagnostic code is active. Proceed to Test Step 4.

• OK - A -04 diagnostic code is active. Proceed to Test Step 3.

• Not OK - No diagnostic code is active.

  Repair: The problem is no longer present. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

Test Step 3. DISCONNECT THE +5 V SENSORS WHILE YOU MONITOR THE ACTIVE DIAGNOSTIC CODES

1. Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes.

   Note: Wait at least 15 seconds in order for the diagnostic codes to become active.

2. Disconnect the following sensors at the sensor connector:

   • Atmospheric pressure sensor

   • Intake manifold air pressure (Boost)

   • Engine oil pressure sensor

   • Oil pressure sensor for the intake valve actuator

3. Wait for 15 seconds after each sensor is disconnected. Check for an active diagnostic code on the electronic service tool.

Expected Result:

The -04 diagnostic code deactivates.

Results:

• OK - The -04 diagnostic code deactivates. The diagnostic code is not active after a specific sensor is disconnected.

  Repair: Reconnect the sensor that is suspected of causing the problem. If the problem returns after the reconnection of the sensor, disconnect the sensor. If the problem disappears after the disconnection of the sensor, replace the sensor. Reconnect all wires to the original configuration. Clear all diagnostic codes. Verify that the repair eliminates the problem.

  STOP

• Not OK - The -04 diagnostic code stays active. Leave the sensors disconnected. Proceed to Test Step 4.

Test Step 4. CHECK THE +5 V SUPPLY WIRE FOR A SHORT TO ENGINE GROUND OR A SHORT TO ANOTHER WIRE IN THE HARNESS

1. Turn the keyswitch to the OFF position.

2. Disconnect the J2/P2 ECM connector.

3. Leave the sensors disconnected at the sensor connectors.

   Note: Wiggle the harness during the following measurements in order to reveal any intermittent short condition.

4. Measure the resistance from the ECM connector P2-72 (+5 V Supply) to every terminal on ECM connector P2 and ECM connector P1. Measure the resistance from the ECM connector P2-72 to the ECM ground strap.

5. Measure the resistance from the ECM connector P2-80 (+5 V Supply) to every terminal on ECM connector P2 and ECM connector P1. Measure the resistance from the ECM connector P2-80 to the ECM ground strap.

Expected Result:

Each resistance measurement is more than 20,000 Ohms.

Results:

• OK - The resistance check does not indicate a short in the engine harness or a short to engine ground. Proceed to Test Step 5.

• Not OK - A resistance measurement is less than 20,000 Ohms. The +5 V supply wire is shorted in the engine harness or the +5 V supply wire is shorted to engine ground.

  Repair: Repair the wire or replace the wire. Clear all logged diagnostic codes. Reconnect all wires to the original configuration. Verify that the repair eliminates the problem.

  STOP

Test Step 5. CHECK THE +5 V SUPPLY AND THE SENSOR COMMON FOR AN OPEN CIRCUIT

1. Install a wire jumper between terminal P2-72 (+5 V Supply) and terminal P2-17 (Sensor Common).

2. Install a wire jumper between terminal P2-80 (+5 V Supply) and terminal P2-54 (Sensor Common).

   Note: Wiggle the harness during the following measurements in order to reveal any intermittent short condition.

3. Record the resistance at each analog sensor connector between terminal A and terminal B.

4. Remove the wire jumpers.

Expected Result:

The resistance is less than 5 Ohms for each measurement.

Results:

• OK - The resistance check does not indicate an open circuit in the engine harness. Proceed to Test Step 6.

• Not OK - A resistance measurement is greater than 5 Ohms. The +5 V supply wire or the sensor common has excessive resistance.

  Repair: Repair the wires or replace the wires. Clear all logged diagnostic codes. Reconnect all wires to the original configuration. Verify that the repair eliminates the problem.

  STOP

Test Step 6. CHECK THE +5 V SUPPLY AT THE ECM

1. Remove the wire G828-WH(White) from ECM connector P2-72 (+5 V Supply). Install a wire jumper with socket terminals on both ends into P2-72.

2. Remove the wire G829-WH(White) from ECM connector P2-17 (Sensor Common). Install a wire jumper with socket terminals on both ends into P2-17.

3. Remove the wire G826-BR(Brown) from ECM connector P2-80 (+5 V Supply). Install a wire jumper with socket terminals on both ends into P2-80.

4. Remove the wire G827-BU(Blue) from ECM connector P2-54 (Sensor Common). Install a wire jumper with socket terminals on both ends into P2-54.

   Note: Disconnecting the common sensor wire from the ECM will generate an open circuit diagnostic code for all sensors that are connected to the sensor common. Troubleshoot the original diagnostic code. Delete the logged diagnostic codes when you are finished.

5. Reconnect ECM connector J2/P2.

6. Turn the keyswitch to the ON position.

7. Measure the voltage between the wire jumper in P2-72 and the wire jumper in P2-17.

8. Measure the voltage between the wire jumper in P2-80 and the wire jumper in P2-54.

9. Turn the keyswitch to the OFF position.

10. Reconnect all wires to the original configuration.

Expected Result:

The voltage is 5.0 ± 0.16 VDC.

Results:

• OK - The voltage is 5.0 ± 0.16 VDC. The voltage is correct.

  Repair: Clear all diagnostic codes. Check for active diagnostic codes. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - The voltage is not 5.0 ± 0.16 VDC. The voltage is incorrect.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM".

  STOP