3500C IMO III Engines Caterpillar

Engine Control Switch - Test

Usage:

Use this procedure to troubleshoot a problem with the start/stop system. Also, use this procedure if the following diagnostic code is active or easily repeated.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
1656-2 Engine Automatic Start Enable Switch : Erratic, Intermittent, or Incorrect	336-2 Engine Control Switch : Erratic, Intermittent, or Incorrect	The two inputs from the ECS are in the opposite state. The code is logged.

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Illustration 1	g03730400
ECM A4

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Illustration 2	g06320027
ECM A5

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Table 2
1. Inspect the Electrical Connectors and the Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information. C. Perform a 45 N (10 lb) pull test on the connector wires. D. Check the harness for abrasions and pinch points.	Connectors and Wiring	Result: The connectors and wiring appear to be OK. Proceed to Test Step 2. Result: There is a problem with the connectors and/or wiring. Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. If the problem is not resolved, proceed to Test Step 2.
2. Check the Status of the Switch Position A. Connect Cat^® Electronic Technician (ET) to the service tool connector. B. Use Cat ET to monitor the status of the following switch: - Start/Run/Stop switch C. Turn the Start/Run/Stop switch to the following positions: - STOP position - START position - STOP position	Switch Status	Result: The parameter for the switch is not correct in either the STOP or the START positions. Proceed to Test Step 3. Result: The status for the switch is correct in both the START and STOP positions. A code for the switch is not active. Repair: The switch appears to be operating correctly. There may be an intermittent problem in the wiring harness or connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information. If the problem is not resolved, proceed to Test Step 3.
3. Check the Wiring for an Open Circuit A. Turn the main disconnect switch to the OFF position. B. Disconnect the J1/P1 and the J2/P2 Electronic Control Module (ECM) connectors. C. Remove the wires from the switch. D. Install a jumper wire between the following wires at the switch: - J842-BK (Black) - R755-OR (Orange) - R756-PK (Pink) E. Measure the resistance between the following terminals at the P1 and P2 ECM connector: - P1-40 and P2-92 - P1-54 and P2-92 F. Return all wiring to the original configuration.	Open Circuit	Result: The measurement indicated a short circuit. The circuit is OK. Proceed to Test Step 4. Result: The measurement indicated an open circuit. Repair: Repair or replace the connector or wiring. If the problem is not resolved, proceed to Test Step 4.
4. Check the Wiring for a Short Circuit A. Disconnect the J1/P1 ECM connector. B. Measure continuity between the following: - P1-40 and Every terminal on the P1 ECM connector - P1-40 and Engine ground - P1-54 and Every terminal on the P1 ECM connector - P1-54 and Engine ground. C. Return all wiring to the original configuration.	Short Circuit	Result: There is no continuity between P1-40/P1-54 and the other circuits at the ECM connectors. There does not appear to be a short circuit in the wiring. Proceed to Test Step 5. Result: The continuity measurement did not indicate an open circuit. Repair: The wires with the low-resistance reading to ground or to each other are damaged. Repair or replace the connectors or wiring. If the problem is not resolved, proceed to Test Step 5.
5. Check the Start/Run/Stop Switch A. Ensure that the switch is not activated. B. Measure the resistance between the normally open terminals at the switch. C. Activate the switch. D. Measure the resistance between the normally open terminals at the switch. Note: The resistance measurement indicates an open circuit when the switch is in the STOP position. The resistance measurement indicates a short circuit when the switch is in the START position. E. Connect Cat ET. F. Use Cat ET to monitor the status of the following switch: - Engine Control Switch (ECS) The status for the ECS should indicate that the switch is in the OFF position. G. Short both jumper wires for the ECS to engine ground. H. Use Cat ET to monitor the status of the following switch: - Engine Control Switch (ECS) The status for the ECS should indicate that the switch is in the ON position.	Switch	Result: The resistance measurement indicates an open circuit when the switch is in the STOP position. The resistance measurement indicates a short circuit when the switch is in the START position. The switch is OK. Return to service. Result: The resistance measurements are not correct. Repair: Replace the Start/Run/Stop switch. If the problem is not resolved, proceed to Test Step 6.
6. Check for Proper Operation of the ECM A. Disconnect the J1/P1 ECM connector. B. Fabricate two jumper wires that are long enough to create a test circuit from the ECM connector to a good source of engine ground. Crimp connector sockets to one end of each of the jumper wires. C. Remove the wires from terminal locations P1-40 and P1-54. Install a jumper wire into each of these terminal locations at the ECM. Note: Ensure that the jumper wires are not touching any other wire and that the wires are insulated from engine ground. D. Connect Cat ET. E. Use Cat ET to monitor the status of the following switch: - Switch-on The status for the switch should indicate that the switch is in the OFF position. F. Short both jumper wires to engine ground. G. Use Cat ET to monitor the status of the following switch: - Switch-on The status for the switch should indicate that the switch is in the ON position.	ECS Status	Result: Cat ET indicates the correct status for the switch. Repair: There may be an intermittent problem in the harness or in a connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for additional information. Return to service. Result: Cat ET did not indicate the correct status for the ECS. Repair: There may be a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Test ECM Mode" for additional information. Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).