GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Depress the brake pedal.

Does the system operate normally?

Go to Testing for Electrical Intermittents

Go to Step 3

3

  1. Disconnect the stop lamp switch.
  2. Connect a fused jumper between the stop lamp switch harness terminals  C and D.

Do the brake lamps center high mount stop lamp (CHMSL) remain illuminated?

Go to Step 4

Go to Step 7

4

Disconnect the body control module (BCM) connector C 6.

Do the brake lamps remain illuminated?

Go to Step 9

Go to Step 5

5

Disconnect the BCM connector C 5.

Does the CHMSL remain illuminated?

Go to Step 10

Go to Step 6

6

Test the following circuits for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

    • The brake pedal switch normally closed contact signal circuit
    • The brake switch 12 volt reference circuit
    • The battery positive voltage circuit to the BCM at connector C 4, terminal 4

Did you find and correct the condition?

Go to Step 13

Go to Step 8

7

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

Did you find and correct the condition?

Go to Step 13

Go to Step 11

8

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

Did you find and correct the condition?

Go to Step 13

Go to Step 12

9

Repair the short to voltage in the stop lamp supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 13

--

10

Repair the short to voltage in the CHMSL supply voltage circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 13

--

11

Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 13

--

12

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

Did you complete the replacement?

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3