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

Disconnect the stop lamp switch.

Do the brake lamps go out?

Go to Step 6

Go to Step 4

4

Remove the CHMSL fuse.

Do the brake lamps go out?

Go to Step 7

Go to Step 5

5

Remove the STOP fuse.

Do the brake lamps go out?

Go to Step 8

Go to Step 9

6

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

Did you find and correct the condition?

Go to Step 11

Go to Step 10

7

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

Did you complete the repair?

Go to Step 11

--

8

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

Did you complete the repair?

Go to Step 11

--

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 11

--

10

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

Did you complete the replacement?

Go to Step 11

--

11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3