ROD AS 4490996 - Caterpillar

Illustration 3 g00856563
P1 ECM connector
Turn the keyswitch to the OFF/RESET position.
Disconnect the J1/P1 ECM connector.
With the switch in the released position, check the resistance between P1:5 (Digital Return) and P1:49 (Compression Brake Switch (N/C)).Note: The resistance should be less than 5 Ohms (continuity).
With the switch in the released position, check the resistance between P1:5 (Digital Return) and P1:54 (Compression Brake Switch (N/O)).Note: The resistance should be greater than 10,000 Ohms (no continuity).
With the switch in the released position, check the resistance between P1:54 (Compression Brake Switch (N/O)) and P1:49 (Compression Brake Switch (N/C)).Note: The resistance should be greater than 10,000 Ohms (no continuity).
Press the compression brake switch and check the resistance between P1:5 (Digital Return) and P1:54 (Compression Brake Switch (N/O)).Note: The resistance should be less than 5 Ohms (continuity).
Press the switch and check the resistance between terminals P1:5 (Digital Return) and P1:49 (Compression Brake Switch (N/C)).Note: The resistance should be greater than 10,000 Ohms (no continuity).
Press the switch and check the resistance between P1:49 (Compression Brake Switch (N/C)) and P1:54 (Compression Brake Switch (N/O)).Note: The resistance should be greater than 10,000 Ohms (no continuity).
Reconnect the J1/P1 ECM connector.Expected Result:The resistance readings should correspond to the information above.Results:
OK - The switch and associated wiring appear to be working correctly. Proceed to Test Step 11.
Not OK - There is either an open or a short in the wiring between the switch and the ECM.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 11. Check the Status of the Switch on ET
Turn the keyswitch to the ON position.
Observe the status of "Engine Retarder Selector Switch Position" on ET.
Observe the status of "Engine Retarder Selector Switch Position" on ET while you press the switch.Expected Result:The status should change accordingly as you operate the switch.Results:
OK - The circuit is functioning normally at this time.Repair: If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The switch signal is reaching the ECM, but the ECM is not responding correctly.Repair: Verify your results before you replace the ECM. Refer to Troubleshooting, "Replacing the ECM".STOP