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 review the Exterior Lighting Systems Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Exterior Lighting Systems Description and Operation

2

Verify that the stop lamps are always ON.

Do the stop lamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Disconnect the stop lamp switch.

Do the stop lamps remain illuminated?

Go to Step 4

Go to Step 5

4

Test for a short to voltage in one of the following circuits or components. Refer to Wiring Repairs .

    • Stop lamp switch signal
    • Center high mounted stop lamp (CHMSL) supply voltage
    • Stop lamp supply voltage
    •  Electronic brake control module (EBCM) center high mounted stop lamp (CHMSL) supply voltage input
    • Powertrain control module (PCM) center high mounted stop lamp (CHMSL) supply voltage input

Did you find and correct the condition?

Go to Step 7

Go to Step 6

5

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

Did you complete the repair?

Go to Step 7

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6

Replace the body control module (BCM). Refer to Control Module References for replacement, setup, and programming.

Did you complete the repair?

Go to Step 7

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7

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3