3176C Engine for the R1600G and the R1700G Load Haul Dumps Sensor Supply - Test Caterpillar

System Operation Description:

Use this procedure to troubleshoot the electrical system if a problem is suspected with a sensor supply or if either of the diagnostic codes in Table 1 is active or easily repeated.

System Operation

The ECM supplies a regulated voltage of 5.0 ± 0.2 VDC to the following sensors:

• Atmospheric pressure sensor

• Coolant temperature sensor

• Engine oil pressure sensor

• Fuel temperature sensor

• Intake manifold air temperature sensor

• Right turbocharger inlet pressure sensor

• Turbocharger outlet pressure sensor

The supply voltage for the sensors is routed from the ECM to terminal A of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal B 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.

Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If the -3 diagnostic code is active, it is possible that a sensor has 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	g01409385
Typical schematic

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the keyswitch to the OFF position.

2. Remove electrical power from the ECM.

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Illustration 2	g01139425
ECM (1) J1/P1 connectors (2) J2/P2 connectors

3. Thoroughly inspect the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.

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

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Illustration 3	g01409630
P2 ECM connector (P2-30) Sensor return (P2-36) Sensor supply

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Illustration 4	g01159881
Sensor connector (A) +5 V sensor supply (B) Sensor return (C) Signal

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

5. Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

6. 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 and 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 AVSpare Electronic Technician (ET) to the service tool connector.

2. Restore electrical power to the ECM.

3. Turn the keyswitch to the ON position.

4. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Look for the following diagnostic codes:
   • 262-3

   • 262-4

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

Expected Result:

No diagnostic codes are active.

Results:

• 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

• Not OK - A 262-3 or 262-4 diagnostic code is active at this time. Proceed to Test Step 3.

Test Step 3. Disconnect the 5 Volt Sensor(s) while you Monitor the Active Diagnostic Codes

1. Monitor the active diagnostic code screen on Cat ET while you disconnect each 5 Volt sensor at the sensor connector. Check for an active 262-3 code or an active 262-4 code.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

2. Disconnect the following sensors one at a time:
   • Atmospheric pressure sensor

   • Coolant temperature sensor

   • Engine oil pressure sensor

   • Fuel temperature sensor

   • Intake manifold air temperature sensor

   • Right turbocharger inlet pressure sensor

   • Turbocharger outlet pressure sensor

Expected Result:

The diagnostic code deactivates when a particular sensor is disconnected.

Results:

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

  Repair: Connect the suspect sensor. If the code returns, replace the sensor with a new sensor. Connect the connector(s). Verify that the problem is resolved.

  STOP

• Not OK - The diagnostic code remains active after a sensor is disconnected. Leave the sensor disconnected. The sensor is not the cause of the diagnostic code. Proceed to Test Step 4.

Test Step 4. Check the +5 V Supply Voltages at the ECM

1. Turn the keyswitch to the OFF position.

2. Disconnect the J2/P2 ECM connector.

3. Fabricate jumper wires that are long enough to be used to measure the supply voltages at the ECM connector. Crimp connector sockets to one end of each jumper wire.

4. Remove the wires from terminal locations P2-36 (+5 V sensor supply) and P2-30 (sensor return). Install a jumper wire into each of these terminal locations.

5. Reconnect the J2/P2 ECM connector.

6. Turn the keyswitch to the ON position.

7. Measure the voltage between the jumper wire in P2-36 (+5 V sensor supply) and the jumper wire in P2-30 (sensor return).

8. Turn the keyswitch to the OFF position.

Expected Result:

The voltage measurement is 5.0 ± 0.2 VDC.

Results:

• OK - The voltage measurement is 5.0 ± 0.2 VDC. The ECM is operating correctly.

  Repair: There is a problem with the harness. Repair the harness or replace the harness.

  STOP

• Not OK - The voltage measurement is not 5.0 ± 0.2 VDC.

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

  STOP