C7.1 Engines and Generator Sets Caterpillar

Indicator Lamp Problem

Usage:

C7.1 770

Note: This procedure is only applicable to applications that have individual indicator lamps.

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:

Wait to start lamp
DPF regen disabled lamp
Low oil pressure lamp
Regeneration active lamp
Wait to disconnect lamp
DPF lamp
Shutdown lamp
Warning lamp

The electronic service tool can be used as a diagnostic aid 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.

During the following procedure, refer to the electrical schematic for the application.

Complete the procedure in the order in which the steps are listed.

Show/hide table

Table 1
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Turn the keyswitch to the OFF position. B. Check that the fuses are not blown. C. Thoroughly inspect the P1 connector and the lamp connections. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. D. Perform a 45 N (10 lb) pull test on each of the wires in the P1 connector that are associated with the indicator lamps. E. Check the screw for the ECM connector for the correct torque of 6 N·m (53 lb in). F. Check the harness for abrasions and for pinch points from the battery to the ECM.	Loose connection or damaged wire	Result: There is a fault in a connector or the wiring. Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all the seals are properly in place and ensure that the connectors are correctly coupled. Replace any blown fuses. Use the electronic service tool to verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly coupled and/or inserted. The harness is free of corrosion, abrasion, and pinch points. The fuses are not blown. Proceed to Test Step 2.
2. Inspect the Lamp A. Disconnect the lamp from the harness. Inspect the lamp to determine if the lamp has failed. B. Measure the resistance across the two terminals of the lamp.	Less than 2000 Ohms	Result: The lamp has greater than 2000 Ohms resistance. Repair: Replace the suspect lamp. Use the electronic service tool to verify that the repair eliminates the fault. Result: The lamp has less than 2000 Ohms resistance. Proceed to Test Step 3.
3. Measure the Input Voltage to the Lamp at the Lamp Socket A. Turn the keyswitch to the ON position. B. Use the electronic service tool to select the "override" function to switch individual lamps ON and OFF. Note: The "Override" function is contained in the "Diagnostics" menu of the electronic service tool. C. Measure the voltage at the lamp socket.	At least 10 VDC for a 12 V system. At least 22 VDC for a 24 V system.	Result: The voltage is not within the expected range. The fault is in the battery supply wiring to the lamp. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to verify that the repair eliminates the fault. Result: The voltage is within the expected range. Proceed to Test Step 4.
4. Check the Wiring for an Open Circuit A. Turn the keyswitch to the OFF position. B. Disconnect the P1 connector. C. Remove the bulb from the suspect lamp. D. Measure the resistance between the ground connection on the lamp holder and the applicable terminal on the P1 connector.	Less than 2.0 Ohms	Result: The measured resistance is greater than 2.0 Ohms - the fault is in the wiring between the lamp holder and the ECM. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to verify that the repair eliminates the fault. Result: The measured resistance is less than 2.0 Ohms. Proceed to Test Step 5.
5. Check the Wiring for a Short Circuit A. Disconnect the P1 connector. B. Check the resistance between the terminal for the suspect lamp and all the other terminals on the P1 connector.	Greater than 100 Ohms	Result: One or more of the measured resistances is less than 100 Ohms. There is a short in the wiring between the lamp holder and the ECM. Repair: Repair the faulty wiring or replace the faulty wiring. Use the electronic service tool to verify that the repair eliminates the fault. Result: All resistance measurements are greater than 100 Ohms. Contact the Dealer Solutions Network (DSN).