Indicator Lamp for Retarder Is On ContinuouslySystem Operation Description:
The indicator lamp should illuminate for 3 seconds upon powering up.
Test Step 1. CHECK THE LAMP CIRCUIT
1. Turn the disconnect switch and the key start switch to the OFF position.
2. Disconnect the machine harness from the brake ECM.
3. At the machine harness connector for the brake ECM, connect J1-15 wire (J766-PU) to frame ground.
4. Turn the disconnect switch and the key start switch to the ON position.
Expected Result:
The indicator lamp should not illuminate.
Results:
* OK - The indicator lamp did not illuminate. Proceed to Test Step 2.
* NOT OK - The indicator lamp illuminates.
Repair: The wire harness is shorted to battery voltage. Repair the wire harness or replace the wire harness.
Stop.
Test Step 2. CHECK THE WIRE FOR THE INDICATOR LAMP
1. Turn the disconnect switch and the key start switch to the OFF position.
2. Remove the lamp from the socket.
3. At the machine harness connector for the brake ECM, check the resistance from J1-15 wire (J766-PU) to all contacts on connector J1 and J2.
Expected Result:
The resistance should be greater than 5000 Ohms.
Results:
* OK - The resistance is greater than 5000 Ohms.
Repair: The ECM is very unlikely to fail. Reconnect all connectors and verify that the lamp is still illuminated. Replace the brake ECM after verifying that the problem is still existing. See Testing And Adjusting, "Electronic Control Module (ECM) - Replace".
Stop.
* NOT OK - The resistance is less than 5000 Ohms on one of the readings.
Repair: The wire harness is shorted to battery voltage. Repair the wire harness or replace the wire harness.
Stop.
