C32 Marine Engines Caterpillar

Use this procedure to troubleshoot any suspect problems with the +5 V analog sensor supply.

This procedure covers the following diagnostic codes:

• 262-03 5 Volt Sensor DC Power Supply short to +batt

• 262-04 5 Volt Sensor DC Power Supply short to ground

The Electronic Control Module (ECM) creates a regulated voltage of 5.0 ± 0.2 VDC that is supplied to terminal A of the harness connectors for these sensors:

• Engine oil pressure sensor

• Boost pressure sensor

• Fuel pressure sensor

• Marine transmission oil pressure sensor

• Marine transmission oil temperature sensor

A +5 V diagnostic code is probably caused by a short circuit to ground or a short circuit to another voltage source in the harness. The next likely cause is a problem with a sensor. The least likely cause is a problem with the ECM.

Illustration 1	g01128972
Schematic for the 5 volt supply

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Turn the keyswitch to the OFF position.

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Illustration 2	g01130301
Engine components for the 5 volt supply (1) J2/P2 ECM connectors (2) Engine oil pressure sensor (3) Boost pressure sensor (4) Connector for the marine transmission oil temperature sensor (5) Connector for the marine transmission oil pressure sensor (6) Fuel pressure sensor

2. Thoroughly inspect connectors (1). Thoroughly inspect the connectors for each pressure sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".

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Illustration 3	g01130317
P2 terminals that are associated with the 5 volt supply (P2-17) Return (P2-72) +5 VDC

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Illustration 4	g01123211
Connectors for the sensors (A) Supply (B) Return (C) Signal

3. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the 5 volt supply.

4. Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

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

Expected Result:

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

Results:

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

• Not OK - The connectors and/or wiring are not OK.

  Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. 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. Refer to Troubleshooting, "Electronic Service Tools".

2. Turn the keyswitch to the ON position.

3. Observe the "Active Diagnostic" screen on Cat ET. Wait at least 15 seconds so that any codes may become active. Look for these codes:
   • 262-03

   • 262-04

Expected Result:

One of the above codes is active.

Results:

• Active 03 code - An 03 diagnostic code is active. Proceed to Test Step 3.

• Active 04 code - An 04 diagnostic code is active. Proceed to Test Step 4.

• No active codes - None of the above codes are active.

  Repair: If any of the above codes are logged and the engine is not running properly, refer to Troubleshooting, "Troubleshooting Without a Diagnostic Code".If the engine is running properly at this time, there may be an intermittent problem in a harness that is causing the codes to be logged. Refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

Test Step 3. Check the Voltage on the +5 V Supply Wire

1. Turn the keyswitch to the OFF position.

2. Disconnect the harness connectors for the following sensors:
   • Engine oil pressure sensor J201/P201

   • Boost pressure sensor J200/P200

   • Fuel pressure sensor J209/P209

   • Marine transmission oil pressure sensor J212/P212

   • Marine transmission oil temperature sensor J137/P137

3. Turn the keyswitch to the ON position.

Note: Be sure to wiggle the harness during the following measurements in order to reveal an intermittent condition.

4. Measure the voltage between terminals A and B at each sensor connector on the engine harness.

Expected Result:

Each voltage measurement is 5.0 ± 0.2 VDC.

Results:

• OK - Each voltage measurement is 5.0 ± 0.2 VDC. The problem appears to be resolved.

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

  STOP

• Not OK - At least one voltage measurement is not 5.0 ± 0.2 VDC. There is a problem with the wiring or with the ECM. Proceed to Test Step 5.

Test Step 4. Disconnect the +5 V Pressure Sensors and Check for Active Diagnostic Codes

1. Disconnect the following sensors one at a time:
   • Engine oil pressure sensor

   • Boost pressure sensor

   • Fuel pressure sensor

   • Marine transmission oil pressure sensor

   • Marine transmission oil temperature sensor

2. Wait for 15 seconds after you disconnect each sensor. Look for the active 262-04 diagnostic code to deactivate.

Expected Result:

The 262-04 diagnostic code deactivates when a particular sensor is disconnected.

Results:

• OK - The 262-04 diagnostic code deactivates when a particular sensor is disconnected.

  Repair: Connect the suspect sensor. If the code returns, replace the sensor.Connect all of the connectors. Verify that the problem is resolved.

  STOP

• Not OK - The 262-04 diagnostic code remains after all of the sensors are disconnected. Leave the sensors disconnected. Proceed to Test Step 5.

Test Step 5. Check the +5 V Supply Wire for a Short to Engine Ground or a Short Circuit

1. Turn the keyswitch to the OFF position.

2. Disconnect the J2/P2 ECM connector. Disconnect the J1/P1 ECM connector.

3. Verify that all of the pressure sensors are disconnected.

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

4. Measure the resistance between terminal P2-72 (+5 V Supply) and all of the other terminals on the P2 connector.

5. Measure the resistance between terminal P2-72 (+5 V Supply) and the engine ground.

Expected Result:

Each resistance measurement indicates an open circuit.

Results:

• OK - Each resistance measurement indicates an open circuit. Proceed to Test Step 6.

• Not OK - At least one of the resistance measurements does not indicate an open circuit. A +5 V supply wire has a short circuit. There may be a problem with a connector.

  Repair: Repair the wire and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 6. Check the +5 V Supply and the Sensor Common for an Open Circuit

1. Install a jumper wire between terminals P2-72 (+5 V Supply) and P2-17 (Return).

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

2. Measure the resistance between terminals A and B at the harness connector for each pressure sensor.

Expected Result:

Each resistance measurement is less than ten Ohms.

Results:

• OK - Each measurement is less than ten Ohms. Proceed to Test Step 7.

• Not OK - At least one resistance measurement is greater than ten Ohms. The +5 V supply wire or the return wire has excessive resistance. There may be a problem in a connector.

  Repair: Repair the wire and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 7. Check the +5 V Supply at the ECM

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

2. Connect ECM connectors J2/P2.

3. Turn the keyswitch to the ON position.

4. Measure the voltage between the jumper wire in P1-72 and the engine ground.

5. Turn the keyswitch to the OFF position.

6. Restore the wiring to the original configuration.

Expected Result:

The voltage measurement is 5.0 ± 0.2 VDC.

Results:

• OK - The voltage measurement is 5.0 ± 0.2 VDC. The problem appears to be resolved.

  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 measurement is not 5.0 ± 0.2 VDC.

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

  STOP