GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

1

  1. Press the brake pedal.
  2. Observe the stop lamps.

Are the stop lamps ON?

Go to Step 3

Go to Step 2

2

Repair the stop lamps before completing this diagnostic table.

Does the center high-mounted stop lamp (CHMSL) work after the tail lamps are repaired?

System OK

Go to Step 3

3

  1. Remove the CHMSL bulb.
  2. Test the CHMSL bulb.

Is the lamp bulb defective?

Go to Step 4

Go to Step 5

4

Replace the CHMSL bulb. Refer to High Mount Stop Lamp Replacement .

Is the repair complete?

System OK

--

5

  1. Disconnect the CHMSL connector.
  2. Use an ohmmeter to measure the resistance between ground and the BK wire in the CHMSL connector.

Does the ohmmeter indicate continuity?

Go to Step 7

Go to Step 6

6

Repair the open circuit between ground and the BK wire in the CHMSL connector.

Is the repair complete?

System OK

--

7

Repair the open circuit between the brake switch and the CHMSL.

Is the repair complete?

System OK

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