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

Observe the stop lamps while pressing the brake pedal.

Does the system operate normally?

Go to Testing for Electrical Intermittents

Go to Step 3

3

Are all the stop lamps inoperative?

Go to Step 6

Go to Step 4

4

Test the supply voltage circuit of the inoperative lamp for high resistance, an open, or a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 5

5

Test the ground circuit of the inoperative lamp for high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 14

Go to Step 8

6

Disconnect the stop lamp switch.

Did the stop lamps illuminate?

Go to Step 9

Go to Step 7

7

Test for the following conditions. Refer to Circuit Testing and Wiring Repairs .

    • A short to voltage in the brake pedal switch normally closed contact signal circuit
    • An open, high resistance, or short to ground in the stop lamp supply voltage circuit
    • An open, high resistance, or short to ground in the center high mount stop lamp (CHMSL) supply voltage circuit

Did you find and correct the condition?

Go to Step 14

Go to Step 10

8

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

Did you find and correct the condition?

Go to Step 14

Go to Step 11

9

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 14

Go to Step 12

10

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

Did you find and correct the condition?

Go to Step 14

Go to Step 13

11

Replace the stop lamp. Refer to Tail Lamp Bulb Replacement or High Mount Stop Lamp Replacement .

Did you complete the replacement?

Go to Step 14

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12

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

Did you complete the replacement?

Go to Step 14

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13

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

Did you complete the replacement?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3