C7.1 Engines For Caterpillar Built Machines Caterpillar

This procedure covers the following codes:

Also use this procedure under the following circumstances:

• The lamps are not receiving battery voltage.

• The lamps are not operating correctly.

The following diagnostic lamps are available:

• High Exhaust System Temperature (HEST) lamp

• Diesel Particulate Filter (DPF) lamp

The electronic service tool can be used as a diagnostic aid in order to switch the individual lamps ON and OFF.

Note: The diagnostic aid that switches the lamps is contained in the "Override" section in the "diagnostics" menu of the electronic service tool.

Illustration 1	g02456217
Schematic of the circuit for the indicator lamps

Illustration 2	g02456218
Typical example of the pin locations on the P1 connector for the indicator lamps (28) DPF lamp (29) HEST lamp (48) Battery (+) (52) Battery (+) (53) Battery (+) (55) Battery (+) (57) Battery (+) (61) Ground (63) Ground (65) Ground (67) Ground (69) Ground (70) Ignition keyswitch

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the keyswitch to the OFF position.

2. Thoroughly inspect the P1 connector and the lamp connections. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the P1 connector that are associated with the indicator lamps.

4. Check the screw for the P1 connector for the correct torque of 6 N·m (53 lb in).

5. Check the harness for abrasions and for pinch points from the battery to the ECM.

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected.Verify that the repair eliminates the fault.

  STOP

Test Step 2. Inspect the Lamp, the Fuse, and the Power Supply

1. Disconnect the lamp from the harness. Inspect the lamp in order to determine if the lamp has failed.

2. Measure the resistance across the two terminals of the lamp. If the resistance is more than 2000 Ohms, the bulb has failed.

3. Check the battery by connecting a test lamp across the terminal of the battery.

Results:

• The lamp has less than 2000 Ohms resistance and the power supply is OK. - The lamp appears to be operating correctly at this time. Proceed to Test Step 3.

• The lamp does not have less than 2000 Ohms resistance or the power supply is not OK. -

  Repair: Replace the suspect component or repair the suspect component. Verify that the repairs have eliminated the fault.

  STOP

Test Step 3. Measure the Input to the Lamp at the Lamp Socket

1. Turn the keyswitch to the ON position.

2. Use the electronic service tool to select the "override" function in order to switch individual lamps ON and OFF.

   Note: The "Override" function is contained in the "Diagnostics" menu of the electronic service tool.

3. Measure the voltage at the lamp socket.

Results:

• The voltage is approximately 24.0 VDC. -

  Repair: Replace the bulb.Verify that the repair eliminates the fault.If the fault persists, measure the resistance across the two terminals of the lamp. If the resistance is more than 2000 Ohms, the replacement bulb has failed. Replace the bulb and repeat the test.

  If the fault persists, proceed to Test Step 4.

• The voltage is not approximately 24 VDC - Proceed to Test Step 5.

Test Step 4. Test the Individual Lamp Circuits

1. Disconnect the P1 connector.

2. Temporarily disconnect the wire from the P1 connector socket that is connected to the suspect lamp.

3. By using a jumper wire, connect the removed wire to the battery-.

4. Turn the keyswitch to the ON position and observe the lamp.

Results:

• The diagnostic lamp comes on while the jumper is connected. Also, the diagnostic lamp goes off when the jumper is removed - The circuit for the diagnostic lamp is functioning correctly. Proceed to Test Step 5.

• The lamp did not turn ON. - The lamp circuit is not functioning correctly. There is a fault in the harness between the lamp and the ECM.

  Repair: Repair the lamp circuit.Verify that the repair eliminated the fault.

  STOP

Test Step 5. Check the Voltage at the ECM

1. Disconnect the P1 connector.

2. Temporarily disconnect the wire from the P1 connector that grounds the suspect lamp.

3. Fabricate the jumper wire with a suitable pin for the P1 connector.

4. Install one end of the jumper wire into the P1 connector socket that is connected to the suspect lamp. Connect a voltage test lamp between the battery+ and the jumper wire.

5. Reinstall the P1 connector to the ECM.

6. Turn the keyswitch to the ON position. Use the electronic service tool to select the override function in order to switch individual lamps ON and OFF.

   Note: The "Override" function is contained in the "Diagnostics" menu of the electronic service tool.

Results:

• The lamp comes ON - The ECM is operating correctly. There is a fault in the wiring or the lamp. Repair the wiring or the lamp, as required. Verify that the repair eliminates the fault.
  
  STOP

• The lamp does not come ON - The ECM is faulty.

  Repair: Perform the following repair:

  1. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  2. Contact the Technical Communicator at a Caterpillar dealer.

     Note: This consultation can greatly reduce the repair time.

  3. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  4. Use the electronic service tool to recheck the system for active diagnostic codes.

  5. If the fault is resolved with the test ECM, reconnect the suspect ECM.

  6. If the fault returns with the suspect ECM, replace the ECM.

  7. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP