3500B Engines for Caterpillar Built Power Modules with the ADEM 3 Electronic Control Module Caterpillar

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

System Operation

The sensor signal for the passive sensor is routed from the ECM to terminal 1 of the sensor connector. The sensor return for the passive sensors is routed from the ECM to terminal 2 of the sensor connector.

Illustration 1	g01441755
Typical schematic

Illustration 2	g01441767
P1 ECM connector (P1-3) Analog sensor return (P1-26) Engine oil temperature sensor

Illustration 3	g01234146
Location of ECM connectors

Illustration 4	g01163206
Sensor connector (Terminal 1) Engine oil temperature sensor (Terminal 2) Analog sensor return

Test Step 1. Check for "Active" or "Logged" Diagnostic Codes

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

2. Turn the main disconnect switch to the ON position.

3. Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes.

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

4. Determine if a diagnostic code has occurred several times.

   Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a poor connection between a socket and a pin in a connector or of a poor connection between a wire and a terminal.

5. Determine if the problem is active and related to one of the following diagnostic codes:

   • -3

   • -4

Expected Result:

A diagnostic code is not active.

Results:

• OK - A diagnostic code is not active.

  Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - An active -3 diagnostic code is present. Proceed to Test Step 2.

• Not OK - An active -4 diagnostic code is present. Proceed to Test Step 3.

Test Step 2. Create a Short at the Sensor Connector

1. Turn the main disconnect switch to the OFF position.

2. Disconnect the suspect sensor.

3. Use a wire jumper in order to create a short between terminal 1 (signal) and terminal 2 (sensor return) at the sensor connector.

4. Turn the main disconnect switch to the ON position.

5. Access the "Active Diagnostic Code" screen on Cat ET. Check for an active -4 diagnostic code for the suspect sensor.

Expected Result:

A -4 diagnostic code is now active for the suspect sensor(s).

Results:

• OK - A -3 diagnostic code was active before creating the short at the sensor connector. A -4 diagnostic code became active after creating the short at the sensor connector. The wiring between the ECM and the sensor connector is OK.

  Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes.

  STOP

• Not OK - A -3 diagnostic code is still active for the suspect sensor. There is an open circuit between the sensor connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 4.

Test Step 3. Create an Open at the Suspect Sensor Connector

1. Turn the main disconnect switch to the OFF position.

2. Disconnect the sensor connector of the suspect sensor with the active -4 diagnostic code.

3. Turn the main disconnect switch to the ON position. Wait at least 30 seconds for activation of the diagnostic codes.

4. Access the "Active Diagnostic Code" screen on Cat ET. Check for an active -3 diagnostic code.

Expected Result:

A -3 diagnostic code is now active for the suspect sensor.

Results:

• OK - A -4 diagnostic code was active before disconnecting the sensor. A -3 diagnostic code became active after disconnecting the sensor. The wiring between the ECM and the sensor connector is OK.

  Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify that there are no active diagnostic codes for the sensor. If there are no active diagnostic codes for the sensor, permanently install the new sensor. Clear any logged diagnostic codes.

  STOP

• Not OK - A -4 diagnostic code is still active for the suspect sensor. There is a short circuit between the sensor connector and the ECM. Leave the sensor disconnected. Proceed to Test Step 4.

Test Step 4. Check the Operation of the ECM

1. Turn the main disconnect switch to the OFF position.

2. Check the operation of the ECM by creating an open at the ECM.

   1. Remove the signal wire for the suspect sensor from the P1 ECM connector. Refer to Illustration 2 for terminal locations.

   2. Install a jumper wire with Deutsch sockets on each end into the socket for the signal wire of the suspect sensor.

   3. Reconnect the ECM connectors.

   4. Turn the main disconnect switch to the ON position.

   5. Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 30 seconds for activation of the code.

      An open circuit diagnostic code -3 should be active for the suspect sensor.

3. Check the operation of the ECM by creating a short at the ECM.

   1. Install a wire jumper between the wire jumper for the signal wire for the suspect sensor and engine ground.

   2. Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 30 seconds for activation of the code.

      A -4 diagnostic code should be active when the wire jumper is installed.

   3. Turn the main disconnect switch to the OFF position.

   4. Remove the wire jumper. Reconnect all wires and connectors.

Expected Result:

A -3 diagnostic code is active when the sensor's signal wire is open at the ECM connector. A -4 diagnostic code is active when the sensor's signal wire is connected to engine ground.

Results:

• OK - The ECM is operating properly. The problem is in the wiring between the ECM and the connector for the sensor.

  Repair: If the code is active for more than one sensor, the problem is most likely in the return wire for the sensor. Repair the return wire for the sensor or replace the harness.

  If the code is only active for one sensor, the problem is most likely in the signal wire for the sensor. Repair the signal wire for the sensor.

  STOP

• Not OK - One of the following conditions exists: The -3 diagnostic code is not active when the sensor signal wire is disconnected. The -4 diagnostic code is not active when the wire jumper is installed.

  Repair: Replace the ECM. Refer to Troubleshooting, "ECM - Replace". Verify that the problem is resolved.

  STOP