P0588 HIGH VOLTAGE DETECTED AT THE SPEED CONTROL VENT DRIVER
When Monitored and Set Condition:
When Monitored: While the engine is running and the Speed control is set.
Set Condition: The Speed control vent commanded state is on and the feedback state is off.
POSSIBLE CAUSES
- SPEED CONTROL SERVO ASSEMBLY
- (V35) SPEED CONTROL VENT SHORTED TO VOLTAGE
- (V35) SPEED CONTROL VENT CIRCUIT SHORTED TO OTHER CIRCUITS
- ECM
- INTERMITTENT CONDITION
- SPEED CONTROL SERVO
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 Speed Control Vacuum Solenoid. Using a 12-volt test light connected to battery positive, check the Speed Control Vacuum Solenoid Output circuit in the Speed Control Assembly 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.
Turn the ignition on. Measure the voltage of the Speed Control vent circuit between the Cruise Control Assembly harness connector and engine ground. Is the voltage above 1 volt?
Yes --> Repair the Speed Control vent circuit for a short to voltage.
No --> Go To 3 -
Turn the ignition off. Measure the resistance between the Speed Control Vacuum circuit and all other circuits in the ECM connectors. Is the resistance less than 10 ohms?
Yes --> Repair the (V35) Speed Control vent circuit shorted to other circuit.
No --> Go To 4 -
Reconnect the ECM harness connectors. Ignition on, engine not running. With the DRBIII®, actuate the Speed Control Vent Solenoid. Using a 12-volt test light connected to battery positive, check the Speed Control Vent Solenoid Output circuit in the Speed Control Assembly 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 --> Go To 5
No --> Replace and program the ECM in accordance with the Service Information. -
Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
Where any problems found?
Yes --> Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
No --> Replace the Cruise control servo.