HOUSING 7W7900 - Caterpillar

Illustration 1 g00700625
SchematicTest Step 1. Check the Electrical Connectors and the Wiring
Thoroughly inspect the J1/P1 ECM connector, the connection at the switch, and any other connectors in the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the suspect switch circuit.
Check the ECM connector (allen head screw) for the proper torque of 6.0 N m (55 lb in).
Check the harness and wiring for abrasion and pinch points from the diagnostic enable switch back to the ECM.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring should be free of corrosion, abrasion or pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem. Stop.Test Step 2. Test the Check Engine Lamp
Ensure that the diagnostic enable switch is in the OFF position.
Turn the keyswitch to the ON position. Do not start the engine. Observe the check engine lamp.Expected Result:The lamp should turn on for five seconds. Then, the lamp should turn off. The lamp will remain on if there is an active diagnostic code.Results:
OK - The check engine lamp circuit is working properly at this time. Proceed to Test Step 3.
Not OK - The check engine lamp is not working properly.Repair: Repair the lamp circuit. Refer to Troubleshooting, "Check Engine Lamp Circuit - Test". Stop.Test Step 3. Test the Diagnostic Enable Switch
Turn the keyswitch to the ON position.
Activate the diagnostic enable switch and observe the check engine lamp.
Deactivate the diagnostic enable switch and observe the check engine lamp.Expected Result:When the diagnostic enable switch is activated, the check engine lamp should flash out flash code 55 (No Diagnostic Codes Detected) or the flash code for any active diagnostic codes. When the diagnostic enable switch is deactivated, the check engine lamp should not flash.Results:
OK - The check engine lamp flashes only when the diagnostic enable switch is activated. The diagnostic enable switch is operating properly at this time.Repair: If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect". Stop.
No Flash - The check engine lamp does not flash regardless of the position of the diagnostic enable switch. Proceed to Test Step 4.
Flashes Continuously - The check engine lamp flashes regardless of the position of the diagnostic enable switch. Proceed to Test Step 6.Test Step 4. Short the Wires at the Switch
Turn the keyswitch to the OFF/RESET position.
Disconnect the wires from the diagnostic enable switch. Record the placement of the wires so the wires can be reconnected to the proper terminals.
Use a jumper wire to short the two wires that were removed from the diagnostic enable switch.
Turn the keyswitch to the ON position. Do not start the engine.
Observe the check engine lamp. The check engine lamp should flash.
Turn the keyswitch to the OFF/RESET position.
Remove the jumper