Hydraulic Auto Apply Parking Brake System Light Flashes On Frequently
Possible Cause | Correction |
|---|---|
The system light may come on while driving. The interval should be greater than 15 minutes. | Less than a 15 minute interval indicates a system problem. |
System fluid leak | Check the reservoir fill level. Look for leaks and fluid spillage. |
Solenoid valve leakdown | Replace the solenoid valve. |
Pump switch defective | Check the pressure cycles. The pressure differential between apply and release should be approximately 350 psi. |
Hydraulic Auto Apply Parking Brake System Light Stays On All the Time
Possible Cause | Correction |
|---|---|
Confirm that the brake is fully released. | Turn the rear wheels and check for drag. |
Check for a short in the light circuit. | Repair or replace the circuit. |
The pump is constantly running. | Check for a system leak, a solenoid valve that failed to open or a motor pressure switch that failed to close. Replace the faulty component. |
Hydraulic Auto Apply Parking Brake System Parking Brake Will Not Rels.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Check the ECM-CRANK fuse, the ALT fuse and the fusible link. Is a fuse or a link blown? | -- | Go to Step 2 | Go to Step 3 |
2 |
Is the repair complete? | -- | Verify repair | -- |
3 | Is the manual parking brake switch in the OFF position? | -- | Go to Step 5 | Go to Step 4 |
4 | Push in the manual parking brake switch to return it to the OFF position. Is the repair complete? | -- | Verify repair | -- |
5 |
Does the motor run? | -- | Go to Step 7 | Go to Step 6 |
6 | Replace the parking brake pump motor. Is the repair complete? | -- | Verify repair | -- |
7 | Use an ohmmeter to check the continuity between the ground and the ground wire (BLK 150) at the parking brake pump motor connector. Is there an open circuit? | -- | Go to Step 9 | Go to Step 8 |
8 | Locate and repair the open wire (BLK 150) between the parking brake pump motor connector and the ground. Is the repair complete? | -- | Verify repair | -- |
9 |
Does the test light illuminate? | -- | Go to Step 11 | Go to Step 10 |
10 | Locate and repair the open RED (2) wire between the parking brake pump relay connector and the gray fusible link. Is the repair complete? | -- | Verify repair | -- |
11 |
Does the light illuminate? | -- | Go to Step 13 | Go to Step 12 |
12 | Locate and repair the open ground wire (BLK 150) between the parking brake pump relay connector and the ground. Is the repair complete? | -- | Verify repair | -- |
13 | Connect a fused jumper at the parking brake pump relay connector between the connector terminals for relay terminals 30 and 87. Does the parking brake pump motor run? | -- | Go to Step 15 | Go to Step 14 |
14 | Locate and repair the open RED (1470) wire between the pump relay connector and the pump motor connector. Is the repair complete? | -- | Verify repair | -- |
15 |
Does the parking brake pump motor run? | -- | Go to Step 17 | Go to Step 16 |
16 | Replace the parking brake pump relay. Is the repair complete? | -- | Verify repair | -- |
17 |
Does the test light illuminate? | -- | Go to Step 19 | Go to Step 18 |
18 | Locate and repair the open RED (5) wire between the fuse block and the auto apply parking brake switch connector. Is the repair complete? | -- | Verify repair | -- |
19 |
Is there continuity across the auto apply parking brake switch while the switch is closed? | -- | Go to Step 21 | Go to Step 20 |
20 | Replace the auto apply parking brake switch. Is the repair complete? | -- | Verify repair | -- |
21 |
Is there continuity between the terminals of the parking brake pressure maintenance switch? | -- | Go to Step 23 | Go to Step 22 |
22 | Replace the parking brake pressure maintenance switch. Is the repair complete? | -- | Verify repair | -- |
23 |
Does the test light illuminate? | -- | Go to Step 25 | Go to Step 24 |
24 | Locate and repair the open circuit in the BLK/YEL (1132) or the DK GRN (901) wire(s). Is the repair complete? | -- | Verify repair | -- |
25 |
Does the test light illuminate? | -- | Go to Step 27 | Go to Step 26 |
26 | Locate and repair the open BLK/YEL (1132) wire between the auto apply parking brake switch connector and the parking brake pressure valve solenoid connector. Is the repair complete? | -- | Verify repair | -- |
27 | Check for continuity between the pressure valve solenoid connector BLK (150) wire and the ground using an ohmmeter. Is there continuity? | -- | Go to Step 29 | Go to Step 28 |
28 | Locate and repair the open BLK (150) wire between the parking brake pressure valve solenoid connector and the ground. Is the repair complete? | -- | Verify repair | -- |
29 | Replace the parking brake pressure valve solenoid. Is the repair complete? | -- | Verify repair | -- |
Hydraulic Auto Apply Parking Brake System Park Brake Light Inoperative
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Check the ECM-CRANK fuse. Is the fuse blown? | -- | Go to Step 2 | Go to Step 3 |
2 | Determine the cause of the short circuit and replace. Is the repair complete? | -- | Verify repair | -- |
3 | Check the bulb. Is the bulb OK? | -- | Go to Step 5 | Go to Step 4 |
4 | Replace the bulb. Is the repair complete? | -- | Verify repair | -- |
5 |
Does the test light illuminate? | -- | Go to Step 7 | Go to Step 6 |
6 | Locate and repair the open PNK/BLK (39) wire between the fuse block and the parking brake light switch connector. Is the repair complete? | -- | Verify repair | -- |
7 |
Does the ohmmeter indicate continuity? | -- | Go to Step 9 | Go to Step 8 |
8 | Replace the parking brake light switch. Is the repair complete? | -- | Verify repair | -- |
9 | Check for continuity of the BLK (150) wire between the instrument cluster connector and the ground. Is there continuity in the wire? | -- | Go to Step 11 | Go to Step 10 |
10 | Locate and repair the open BLK (150) wire between the instrument cluster connector and the ground. Is the repair complete? | -- | Verify repair | -- |
11 | Locate and repair the open wire between the parking brake light switch connector, splice 381, and the instrument cluster connector. Is the repair complete? | -- | Verify repair | -- |
