KIT-SEAL 2624405 - Caterpillar

Illustration 1 g01275678
Schematic of the Auto Retarder Control (ARC) ON/OFF Switch
This switch has two inputs to the Brake ECM. During normal operation, one input is open. The other input is grounded. When a circuit is measured with a voltmeter, an open circuit will measure approximately 5 DCV and a closed circuit will measure approximately 0 DCV. An FMI 04 diagnostic code is recorded when the status of both the inputs are grounded.The possible causes of this diagnostic code are listed below:
The "N/O" signal circuit (wire K986-PK(Pink)) is shorted to ground.
The "N/C" signal circuit (wire K985-BR(Brown)) is shorted to ground.
The ARC ON/OFF switch has failed.
The ECM has failed. This is unlikely. Test Step 1. CHECK THE SWITCH
Turn the key start switch to the ON position.
The diagnostic code is active.
Remove the wire from contact 2 (wire A294-BK(Black)) at the switch.
Toggle the switch and note the status of the diagnostic code. Expected Result:The diagnostic code is no longer active in either position.Results:
OK - The diagnostic code is no longer active in either position.Repair: The ARC ON/OFF switch has failed. Replace the switch. Verify that the new switch corrects the diagnostic code.STOP
NOT OK - The diagnostic code is active in at least one of the positions. Proceed to Test Step 2.Test Step 2. CHECK THE SIGNAL CIRCUITS FOR A SHORT TO GROUND
Turn the key start switch to the OFF position.
Disconnect the machine harness connector J1 from the Brake ECM.
Measure the resistance between contact J1-33 (wire K986-PK(Pink)) and frame ground.
Measure the resistance between contact J1-40 (wire K985-BR(Brown)) and frame ground. Expected Result:The resistances should be greater than 5000 ohms.Results:
OK - The resistances are greater than 5000 ohms.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the diagnostic code is still present, replace the ECM. Refer to 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 circuit with the low resistance is shorted in the machine harness. Repair the machine harness or replace the machine harness.STOP