P0596 HIGH VOLTAGE DETECTED AT THE S/C BRAKE SWITCH OUTPUT
When Monitored and Set Condition:
When Monitored: While the key is on.
Set Condition: The voltage detected on the Speed Control Servo is below a calibrated value for a calibrated
amount on time.
POSSIBLE CAUSES
- SPEED CONTROL SERVO ASSEMBLY
- (V32) S/C 12-VOLT SOURCE SHORTED TO OTHER CIRCUITS
- (V32) S/C BRAKE SWITCH OUTPUT SHORTED TO GROUND
- ECM
- INTERMITTENT CONDITION
DIAGNOSTIC PROCEDURE
-
Turn the ignition off. Disconnect the Speed control servo harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running. With the DRBIII®, actuate the S/C 12-volt source. Using a 12-volt test light connected to battery ground, check the S/C brake switch Output circuit in the Speed Control servo harness connector.
NOTE: The test light must illuminate brightly.
Compare the brightness to that of a direct connection to the battery. Does the test light cycle on and off and illuminate brightly?
Yes --> Replace the speed control servo assembly.
No --> Go To 2 -
Turn the ignition off. Disconnect the ECM harness connector(s).
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the S/C brake switch output circuit between the Speed Control assembly connector and battery negative. Is the resistance greater than 100k Ohms?
Yes --> Go To 3
No --> Repair the (V32) S/C brake switch output shorted to ground. -
Measure the resistance between the S/C 12-volt source circuit in the ECM harness connector and all other circuits in the ECM harness connectors. Is the resistance less than 100k Ohms?
Yes --> Go To 4
No --> Repair the (V32) S/C 12-volt source circuit shorted to other circuit. -
Turn the ignition off. Reconnect the ECM harness connectors. Ignition on, engine not running. With the DRBIII®, actuate the S/C 12-volt source. Using a 12-volt test light connected to battery ground, check the S/C brake switch Output circuit in the Speed Control servo harness connector.
NOTE: The test light must illuminate brightly.
Compare the brightness to that of a direct connection to the battery. Does the test light cycle on and off and illuminate brightly?
Yes --> Test Complete.
No --> Replace and program the ECM in accordance with the Service Information.