Caterpillar Monitoring System for Electronic Modular Control Panel Caterpillar

Illustration 1	g00649488
Schematic Of The Left Side Exhaust Temperature Sensor

Note: Ensure that the desired diagnostic code is on hold. Ensure that the "SERV CODE" indicator is on. Use the electrical system schematic for the engine that is being serviced in order to find the connector contact on the Main Display Module which corresponds to the current CID.

Ensure that the desired diagnostic code is on hold. Ensure that the "SERV CODE" indicator is on. Use the electrical system schematic for the engine that is being serviced in order to find the connector contact on the Main Display Module which corresponds to the current CID.

The diagnostic code is recorded when the Main Display Module reads the sensor signal and the module determines that the signal is abnormal.

The following examples are possible causes of this diagnostic code:

• The LH exhaust temperature sensor has a problem.

• The ground circuit for the LH exhaust temperature sensor in the engine harness is open.

• The signal circuit for the LH exhaust temperature sensor in the engine harness is shorted to +battery.

• The signal circuit for the LH exhaust temperature sensor in the engine harness is open or the connector is disconnected.

• The Main Display Module has a problem.

1. Check Readout and Harness.

   1. Turn the ECS to the OFF/RESET position.

   2. Check for loose connections and check for corroded terminal connections to the LH exhaust temperature sensor.

   3. Clean the corroded terminals and tighten the loose connections.

   4. Turn the ECS to the COOLDOWN/STOP position.

      Expected Result: The SERV CODE indicator should be on for the CID 0827 FMI 08 diagnostic code.

      Results:

      • OK - The diagnostic code is present. The SERV CODE indicator is ON. Go to 3.

      • NOT OK - The diagnostic code is NOT present. The SERV CODE indicator is not on. The initial problem was probably caused by a poor connection in the harness. STOP.

2. Measure LH Exhaust Temperature Sensor Supply Wire.

   1. Turn the ECS to the COOLDOWN/STOP position.

   2. At the LH exhaust temperature sensor, use the 7X-1710 Multimeter Probe and measure the voltage from the ground wire (contact B) to the supply wire (contact A).

      Expected Result: The voltage is 8.0 ± 0.5 DCV.

      Results:

      • YES - The voltage is 8.0 ± 0.5 DC Volts. The voltage is correct. Go to 3.

      • NO - If The voltage is less than 0.5 DC Volts. The harness wiring has a problem. There is an open circuit, a short to ground in the supply wire for the LH exhaust temperature sensor, or a poor connection. Repair the harness or replace the harness. If the cause of the diagnostic code is not found, go to 3.

3. Measure LH Exhaust Temperature Sensor Signal Voltage.

   1. Turn the ECS to the COOLDOWN/STOP position.

   2. At the LH exhaust temperature sensor, use the 7X-1710 Multimeter Probe and measure the voltage from the ground wire (contact B) to the supply wire (contact A).

      Expected Result: The voltage is between approximately 1.0 and 7.0 DCV.

      Results:

      • OK - The voltage is between approximately 1.0 and 7.0 DC Volts. The signal voltage at the sensor is correct. Go to 4.

      • NOT OK - The voltage is not between approximately 1.0 and 7.0 DC Volts. The signal voltage at the sensor is not correct. If the voltage is greater than 7.0 DCV go to 5. If the voltage is less than 1.0 DCV go to 6.

4. Measure LH Exhaust Temperature Sensor Signal Voltage.

   1. Turn the ECS to the COOLDOWN/STOP position.

   2. Use the 7X-1710 Multimeter Probe and measure the voltage from the Main Display Module's contact for the ground wire to the contact for the signal wire.

      Expected Result: The voltage is identical to the voltage that was recorded in Step 3.

      Results:

      • YES - The voltage is identical to the voltage that was recorded in Step 3. The Main Display Module is receiving a valid signal voltage. The Main Display Module has a problem. Replace the Main Display Module. See Testing And Adjusting, "Module - Replace" for more information.

      • NO - The voltage is not the same as in STEP 3. The engine harness has an open circuit in the signal circuits or ground circuits. Repair the engine harness or replace the engine harness.

5. Check for Short to +Battery.

   1. Turn the ECS to the OFF/RESET position.

   2. Disconnect the connector for the Main Display Module and disconnect the connector for the LH exhaust temperature sensor.

   3. Use the 7X-1710 cable probes and measure the resistance between +battery and the signal wire (contact C) for the LH exhaust temperature sensor.

      Expected Result: The resistance is greater than 5000 ohms.

      Results:

      • YES - The resistance is greater than 5000 ohms. The harness signal wire is correct. Replace the Main Display Module. See Testing And Adjusting, "Module - Replace" for more information.

      • NO - The resistance is less than 5000 ohms. Repair the harness or replace the harness.

6. Check for Short to Ground.

   1. Turn the ECS to the OFF/RESET position.

   2. Disconnect the connector for the Main Display Module and disconnect the connector for the LH exhaust temperature sensor.

   3. Use the 7X-1710 cable probes and measure the resistance between ground and the signal wire (contact C) for the LH exhaust temperature sensor.

      Expected Result: The resistance is less than 5000 ohms.

      Results:

      • YES - The resistance is less than 5000 ohms. Repair the harness or replace the harness.

      • NO - The resistance is greater than 5000 ohms. The harness signal wire is correct. Replace the Main Display Module. See Testing And Adjusting, "Module - Replace" for more information.