GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Important: Verify the park brake lever bolts and park brake warning switch screw are tight and NOT corroded. Also, verify that there is proper battery voltage present.

1

Did you perform the Hydraulic Brake Diagnostic System Check?

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Go to Step 2

Go to Hydraulic Brake Diagnostic System Check

2

  1. Turn the ignition switch to RUN.
  2. Use the scan tool to establish communication with the following components on the class 2 data link:
  3. • The Body Control Module (BCM)
    • The Electronic Brake Control Module (EBCM)
    • The instrument cluster

Are all of the modules communicating with the scan tool?

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Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Data Line in Data Link Communications

3

Use the scan tool to turn the brake warning lamp on and off.

Does the lamp turn on and off?

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Go to Step 4

Go to Step 16

4

Is the brake warning lamp only inoperative with the park brake engaged?

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Go to Step 8

Go to Step 5

5

Is the brake warning lamp only inoperative when the hydraulic brake system has low brake pressure in the front or rear brakes?

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Go to Step 11

Go to Step 6

6

Is the brake warning lamp only inoperative during the instrument cluster bulb test with the ignition switch in off, run or start positions.

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Go to Step 16

Go to Step 7

7

Is the brake warning lamp completely inoperative?

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Go to Step 16

Go to Hydraulic Brake Diagnostic System Check

8

Ground CKT 1134 (LT BLU) at the park brake warning switch connector.

Does the brake warning lamp turn ON?

--

Go to Step 9

Go to Step 10

9

Replace the park brake warning switch.

Is the repair complete?

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Go to Hydraulic Brake Diagnostic System Check

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10

Repair the open in CKT 1134 (LT BLU) between the park brake warning switch and the BCM.

Is the repair complete?

--

Go to Hydraulic Brake Diagnostic System Check

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11

Ground CKT 680 (PPL) at the brake pressure warning switch.

Does the brake warning lamp turn ON?

--

Go to Step 12

Go to Step 15

12

Verify ground CKT 350 (BLK) at the brake pressure warning switch.

Does a ground exist?

--

Go to Step 13

Go to Step 14

13

Replace the brake pressure warning switch.

Is the repair complete?

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Go to Hydraulic Brake Diagnostic System Check

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14

Repair the open in CKT 350 (BLK) between the brake pressure warning switch and G102.

Is the repair complete?

--

Go to Hydraulic Brake Diagnostic System Check

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15

Repair the open in CKT 680 (PPL) between the brake pressure warning switch and the EBCM.

Is the repair complete?

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Go to Hydraulic Brake Diagnostic System Check

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16

Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

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Go to Hydraulic Brake Diagnostic System Check

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