GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Hydraulic Brake Schematics

Connector End View Reference: Hydraulic Brake Connector End Views or Displays and Gages Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Inspect the brake fluid level.

Is the brake fluid level OK?

Go to Step 3

Go to Brake Fluid Loss

3

  1. Turn ON the ignition, with the engine OFF.
  2. Release the park brake.
  3. With a scan tool, observe the Park Brake Switch parameter in the Park Brake data list.

Does the scan tool indicate that the Park Brake Switch parameter is OFF?

Go to Step 4

Go to Step 5

4

With a scan tool, observe the Brake Fluid Level Status parameter in the Hydraulic Brakes data list.

Does the scan tool indicate that the Brake Fluid Level Status parameter is OK?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 6

5

  1. Turn OFF the ignition.
  2. Disconnect the park brake switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Park Brake Switch parameter.

Does the scan tool indicate that the Park Brake Switch parameter is Off?

Go to Step 9

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Disconnect the brake fluid level switch.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Brake Fluid Level Status parameter.

Does the scan tool indicate that the Brake Fluid Level Status parameter is OK?

Go to Step 10

Go to Step 8

7

Test the signal circuit of the park brake switch for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 15

Go to Step 11

8

Test the signal circuit of the brake fluid level switch for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 15

Go to Step 11

9

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 15

Go to Step 12

10

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 15

Go to Step 13

11

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

Did you find and correct the condition?

Go to Step 15

Go to Step 14

12

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

Did you complete the repair?

Go to Step 15

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13

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

Did you complete the repair?

Go to Step 15

--

14

Replace the IPC. Refer to Control Module References for replacement, setup, and programming.

Did you complete the repair?

Go to Step 15

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15

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2