Park Brake System Diagnosis (J55, JL9)

Step	Action	Yes	No
DEFINITION: This diagnostic table is designed to diagnose ONLY the mechanical components of the PARK brake system in order to determine if the PARK brake system is operating properly. You will be directed by the appropriate Symptom table to go to other brake system diagnostic tables as appropriate.
1	Were you sent here from a Hydraulic Brake Symptom table?	Go to Step 4	Go to Step 2
2	Were you sent here from a Park Brake Symptom table?	Go to Step 4	Go to Step 3
3	Raise and support the vehicle. Lifting and Jacking the Vehicle (ZL1) , or Lifting and Jacking the Vehicle (Convertible) With the park brake RELEASED, attempt to rotate the rear wheels to check the rear brakes for a significant amount of drag. Do the rear brakes have a significant amount of drag?	Go to Step 6	Go to Step 4
4	Apply the park brake. Attempt to rotate the rear wheels to check the rear brakes for a significant amount of drag. Do the rear brakes have a significant amount of drag?	Go to Step 5	Go to Step 6
5	Remove the park brake actuator. Rear Parking Brake Actuator Replacement  Attempt to rotate the rear wheels to check the rear brakes for a significant amount of drag. Do the rear brakes still have a significant amount of drag?	Go to Step 6	Go to Step 7
6	Have an assistant apply the brakes. Attempt to rotate the rear wheels to check the rear brakes for a significant amount of drag. Repeat steps 1-2 for the opposite rear wheel. Rotate the rear wheels to check the brake for a significant reduction of drag. Did the brake calipers apply and release properly?	Go to Step 7	Go to Step 8
7	Inspect the parking brake actuators for proper operation and replace if necessary. Rear Parking Brake Actuator Replacement  Did you complete the replacement?	Go to Step 10	-
8	Courtesy of GENERAL MOTORS COMPANY Insert the appropriate hex-key tool (2) into the input shaft (1) of the rear brake caliper housing. Using the hex-key tool (2) rotate the input shaft (1) one full rotation clockwise. Check to see if the brake has released. If it has not released make additional quarter turns clockwise until the brake has released. Did these steps release the brake?	Go to Step 10	Go to Step 9
9	Replace the appropriate rear brake caliper. Rear Brake Caliper Replacement (JL9, J55) Did you complete the replacement?	Go to Step 10	-
10	Connect any components that were disconnected during diagnosis. Did you complete the operation?	Park Brake System OK	-