GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The instrument panel cluster (IPC) illuminates the red brake warning indicator by supplying ground to the lamp. The electronic brake control module (EBCM) sends a class 2 message to the IPC requesting illumination. The park brake switch is wired to the IPC logic. The red brake warning indicator also illuminates when the park brake is applied.

Step

Action

Yes

No

Schematic Reference: Hydraulic Brake Schematics and Instrument Cluster Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Verify a fault is present.

Does the system operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Install a scan tool.
  2. Select the instrument panel cluster (IPC) Special Functions menu on the scan tool.
  3. Command all of the IPC indicator lamps On.

Does the brake warning indicator illuminate?

Go to Step 4

Go to Step 18

4

Apply the park brake.

Does the brake warning indicator illuminate?

Go to Step 5

Go to Step 6

5

  1. Disconnect the brake fluid level switch harness connector.
  2. Connect a fused jumper wire between the brake fluid level switch output circuit and the ground circuit of the brake fluid level switch. Refer to Using Fused Jumper Wires .

Does the brake warning indicator illuminate?

Go to Step 13

Go to Step 7

6

  1. Disconnect the park brake switch harness connector.
  2. Connect a fused jumper wire between the park brake switch output circuit and a good ground. Refer to Using Fused Jumper Wires .

Does the brake warning indicator illuminate?

Go to Step 11

Go to Step 8

7

Connect a fused jumper wire between the brake fluid level switch output circuit and a good ground. Refer to Using Fused Jumper Wires .

Does the brake warning indicator illuminate?

Go to Step 9

Go to Step 10

8

  1. Remove the IPC. Refer to Instrument Cluster Replacement .
  2. Test park brake switch output circuit for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 17

9

Repair the open in the ground circuit of the brake fluid level switch. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 19

--

10

Test the brake fluid level switch input circuit for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 15

11

Inspect for poor connections at the harness connector of the park brake switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 12

12

Replace the park brake switch. Refer to Parking Brake Indicator Switch Replacement .

Did you complete the replacement?

Go to Step 19

--

13

Inspect for poor connections at the harness connector of the brake fluid level switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 14

14

Replace the brake fluid level switch. Refer to Brake Fluid Level Indicator Switch Replacement .

Did you complete the replacement?

Go to Step 19

--

15

Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 16

16

Replace the EBCM. Refer to Control Module References .

Did you complete the replacement?

Go to Step 19

--

17

Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 18

18

Replace the IPC. Refer to Control Module References .

Did you complete the replacement?

Go to Step 19

--

19

Verify the system is repaired.

Does the system operate normally?

System OK

Go to Step 3