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

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 12

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 12

Go to Step 8

6

Test the 5 volt signal circuit of the brake pedal position sensor 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 12

Go to Step 7

7

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

    • The stop lamp supply voltage
    • The CHMSL supply voltage

Did you find and correct the condition?

Go to Step 12

Go to Step 9

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 12

Go to Step 10

9

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

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

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

Did you complete the replacement?

Go to Step 12

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11

Important: A calibration of the Brake Pedal Position Sensor needs to be performed upon replacement. Refer to Brake Pedal Position Sensor Calibration .

Replace the brake pedal position sensor. Refer to Brake Pedal Position Sensor Replacement .

Did you complete the replacement?

Go to Step 12

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12

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3