C18 Marine Auxiliary and Marine Generator Set Engines Caterpillar

Indicator Lamp - Test

Usage:

C18 DTP

Use this procedure to troubleshoot any suspect problems with the following indicator lamps:

Low oil pressure lamp
High coolant temperature lamp
Low coolant level lamp
Maintenance indicator lamp
Warning lamp
Diagnostic lamp

The indicator lamps are activated by the Electronic Control Module (ECM) in order to inform the operator of various engine conditions. When the keyswitch is placed in the ON position, the diagnostic lamp and the warning lamp are illuminated by the ECM for a brief period.

The ECM provides high side drivers and low side drivers for the lamp outputs.

The following lamps utilize a low side driver for the lamp output at the ECM:

Low oil pressure lamp
High coolant temperature lamp
Low coolant level lamp

The following lamps utilize a high side driver for the lamp output at the ECM:

Maintenance indicator lamp
Warning lamp
Diagnostic lamp

The most likely cause of a problem with an indicator lamp is the bulb. The next most likely cause is a problem with a wire or with a connector. The least cause is a problem with the ECM.

Note: An override feature is available in Caterpillar Electronic Technician (ET) for each of the lamp circuits. The override can be used to troubleshoot the lamp circuits.

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Illustration 1	g01374137
Schematic for the engine's lamp circuits

Note: There are configuration parameters that are associated with the low coolant level lamp and the maintenance indicator lamp. Ensure that these parameters are configured correctly prior to troubleshooting the lamp circuits. Refer to Troubleshooting, "Configuration Parameters" for information that is related to the configuration of the lamp circuits.

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Illustration 2	g06113045
Locations of the connectors that are associated with the lamp circuits (typical left rear engine view) (1) Engine interface connectors (2) J2/P2 ECM connectors (3) J1/P1 ECM connectors

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Illustration 3	g01367230
Terminal locations at the P1 ECM connector that are for the lamp circuits (P1-19) Diagnostic lamp (P1-20) Warning lamp (P1-28) Low oil pressure lamp (P1-29) High coolant temperature lamp (P1-30) Low coolant level lamp

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Illustration 4	g01367240
Terminal locations at the P2 ECM connector that are for the lamp circuits (P2-6) Maintenance indicator lamp

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Illustration 5	g01367257
Terminal locations at the engine interface connector that are for the lamp circuits (Terminal 20) Low coolant level lamp (Terminal 21) High coolant temperature lamp (Terminal 22) Maintenance indicator lamp (Terminal 23) Low oil pressure lamp (Terminal 24) Diagnostic lamp (Terminal 25) Warning lamp

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Table 1
Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the Wiring A. Remove electrical power from the ECM. B. Thoroughly inspect connectors (1), (2), and (3). Also, thoroughly inspect any of the other connectors that are associated with the lamp circuits. Refer to the Schematic of the engine for connector locations. Refer to Troubleshooting, "Electrical Connectors - Inspect". C. Perform a 45 N (10 lb) pull test on each of the wires for the lamp circuits. D. Check the torque of the allen head screw on the ECM connectors and the engine interface connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values. E. Check the harness and the wiring for abrasion and for pinch points from the dash display back to the ECM.	Allof the 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.	Result: The harness and connectors appear to be in good repair. Proceed to Test Step 2. Result: The connectors and/or wiring need repair. Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are coupled completely. Verify that the repair eliminates the problem.
2. Check for Proper Operation of the Lamp Circuits A. Connect Cat ET to the service tool connector. B. Restore electrical power to the ECM. Turn the keyswitch to the ON position. C. Select the "Override Parameters" option from the "Diagnostic Tests"on Cat ET. D. Use the correct override parameter to power the circuit for the suspect lamp. E. Remove electrical power from the ECM. Turn the keyswitch to the OFF position.	The suspect lamp illuminates when the override is turned on.	Result: The suspect lamp illuminates when the override is on. There does not appear to be a problem with the lamp circuit at this time. The problem may have been related to a faulty connection in the harness. Carefully reinspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect". Result: The suspect lamp does not illuminate when the override is on. Inspect the lamp and the lamp socket for the suspect circuit. Use a lamp socket that is known to be operational to check the condition of the lamp, if necessary. If either of the components are questionable, replace the component. Retest the circuit. If the problem persists or if the components of the lamp assembly appear to be in good repair, proceed to Test Step 3.
3. Use the Override to Check the Wiring Harness A. Remove the lamp for the suspect circuit from the lamp socket. B. Connect a test lamp between the terminal of the lamp socket that is for the driver circuit from the ECM and the correct return for the circuit: a. Connect a test lamp in the following manner if the lamp uses a high side driver as an output at the ECM: Connect the test lamp between the terminal of the lamp socket that is for the driver circuit from the ECM and the −Battery terminal. b. Connect a test lamp in the following manner if the lamp uses a low side driver as an output at the ECM: Connect the test lamp between the terminal of the lamp socket that is for the driver circuit from the ECM and the "R" terminal of the keyswitch. C. Restore electrical power to the ECM. Turn the keyswitch to the ON position. D. Use the override parameter in Cat ET to power the circuit for the suspect lamp. E. Remove electrical power from the ECM. Turn the keyswitch to the OFF position.	The test lamp illuminates when the override is turned on.	Result: The test lamp illuminates when the override is turned on. The circuit between the ECM and the lamp socket is OK. Perform the following procedure: The circuit between the ECM and the lamp socket is OK. Perform the following procedure: 1. Check for continuity between the terminal for the return circuit of the lamp socket and the proper return that is for the suspect lamp: a. Use this procedure for a lamp circuit that uses a high side driver as an output at the ECM: Check for continuity in the wiring that is between the lamp socket and the −Battery. If the circuit is continuous then the lamp or the lamp socket is the cause of the problem. Replace the faulty lamp or the faulty lamp socket. Verify that the repair eliminates the original problem. If the circuit is not continuous then there is a problem in the wiring that is between the lamp socket and the −Battery. Repair the circuit. Verify that the repair eliminates the original problem. b. Use this procedure for a lamp circuit that uses a low side driver as an output at the ECM: Check for continuity in the wiring that is between the lamp socket and the "R" terminal of the keyswitch. If the circuit is continuous then the lamp or the lamp socket is the cause of the problem. Replace the faulty lamp or the faulty lamp socket. Verify that the repair eliminates the original problem. If the circuit is not continuous then there is a problem in the return circuit for the lamp. Repair the return circuit that is between the lamp socket and the "R" terminal of the keyswitch. Verify that the repair eliminates the original problem. Result: The test lamp does not illuminate when the override is turned on. There may be a problem in the keyswitch circuit. Verify that there is power at the "R" terminal of the keyswitch while the keyswitch is in the ON. If there is not power at"R" terminal of the keyswitch then there is a problem with the keyswitch or the keyswitch circuit. Refer to Troubleshooting, "Electrical Power Supply - Test" for information that is related to troubleshooting the keyswitch circuit. Ifthere is power at the"R" terminal of the keyswitch then there is a problem in the harness or in a connector that is between the ECM and the lamp socket. There may be a problem with the ECM. Proceed to Test Step 4.
4. Check for Proper Operation of the ECM A. Ensure that electrical power has been removed from the ECM. B. Disconnect the appropriate ECM connectors for the suspect lamp circuit. C. Remove the signal wire for the suspect lamp from the ECM connector. Refer to Illustration 1 for the lamp's correct terminal location. D. Fabricate a jumper wire that is long enough to create a test circuit across the ECM connector. Crimp a connector socket to one end of the jumper wire. E. Install the socket end of the jumper wire into the terminal location that is for the signal wire of the suspect lamp. F. Reconnect the ECM connectors. G. Install a 7X-1709 Multimeter Probe into the correct terminal location that is for the suspect sensor's return at the ECM connector: NOTE: Ensure that the multimeter probe is in good repair. A bent probe may contact other terminals inside the connector. a. Connect the multimeter probe in the following manner if the lamp uses a high side driver as an output at the ECM: Install the multimeter probe into terminal location P1-61 (−Battery). b. Connect the multimeter probe in the following manner if the lamp uses a low side driver as an output at the ECM: Install the multimeter probe into terminal location P1-70 (keyswitch). H. Install a test lamp between the loose end of the jumper wire and the loose end of the multimeter probe. I. Restore electrical power to the ECM. Turn the keyswitch to the ON position. J. Use the override parameter in Cat ET to power the circuit for the suspect lamp. K. Remove electrical power from the ECM. Turn the keyswitch to the OFF position. Restore all wiring to the original configuration.	The test lamp illuminates when the override is turned on.	Result: The test lamp illuminates when the override is on. The ECM is operating correctly. There is a problem in the harness or in a connector that is between the ECM and the lamp socket. Repair the harness and/or the connector or replace the harness and/or the connector. If necessary, replace parts. Verify that the repair eliminates the problem. Result: The test lamp does not illuminate when the override is on. The harness that is for the lamp circuit is OK. The ECM is not powering the lamp circuit correctly. Replace the ECM. Refer to Troubleshooting, "ECM - Replace" for details.