HEATER GP-CAB 1640490 - Caterpillar

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Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
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Left side engine view (typical example) (1) J1/P1 ECM connectors
Thoroughly inspect connector (1). Also inspect the harness for the check engine lamp. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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P1 connector (28) Check engine lamp (52) +Battery (65) -Battery
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the check engine lamp.
Check the allen head screw on the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.
Check the harness and wiring for abrasion and pinch points from the battery to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are in need of repair.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.STOPTest Step 2. Check for Normal Operation of the Check Engine Lamp
Turn the keyswitch to the ON position. Monitor the check engine lamp. The ECM will illuminate the lamp for five seconds.
Turn the keyswitch to the OFF position.Expected Result:The check engine lamp illuminates for five seconds after the keyswitch is turned to the ON position.Results:
OK - The check engine lamp is operating normally.Repair: There may be an intermittent problem with the wiring and/or the connectors. Repair the lamp circuit or send the vehicle to the OEM dealer for repairs.STOP
Not OK - The check engine lamp does not turn on. Proceed to Test Step 3.Test Step 3. Test the Check Engine Lamp Circuit
Fabricate a jumper wire that can be used to test the circuit. Crimp connector pins to each end of the jumper.
Disconnect the J1/P1 ECM connectors.
Insert the jumper into terminal P1-28 (change oil lamp).
Insert the other end of the jumper wire into terminal P1-52 (-Battery).
While the lamp is being watched, insert the jumper wire and remove the jumper wire from terminal P1-65.
Remove the jumper wire from the ECM connector.Expected Result:Result 1 The check engine lamp turns on while the jumper is connected. Also, the check engine lamp turns off when the jumper is removed.Result 2 The check engine lamp does not turn on while the jumper is connected to both sockets.Result 3 The check engine lamp remains on while the ECM connector is disconnected.Results:
Result 1 - The lamp turns on and off when the ECM is bypassed. The circuit for the check engine lamp is OK. Proceed to Test Step 4.
Result 2 - The check engine lamp does not illuminate when the ECM is bypassed.Repair: The vehicle's lamp circuit is not functioning properly. The lamp is probably burned out or there is a problem in the lamp circuit from