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 inoperative.

Do the stop lamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Is only one lamp inoperative?

Go to Step 4

Go to Step 5

4

Test the inoperative bulb, LED, or tail lamp printed circuit board for an open or poor terminal contact. Refer to Circuit Testing .

Did you find a condition?

Go to Step 10

Go to Step 9

5

Connect a test lamp from ground to the supply voltage circuit terminal of the inoperative lamp socket or connector and apply the service brake. Refer to Circuit Testing .

Does the test lamp illuminate?

Go to Step 7

Go to Step 6

6

Remove the stop lamp switch and install a fused jumper between the stop lamp switch battery positive voltage circuit terminal and the stop lamp switch signal circuit terminal of the stop lamp switch connector.

Do the stop lamps illuminate?

Go to Step 11

Go to Step 8

7

Repair the open or high resistance in the ground circuit of the inoperative lamp. Refer to Wiring Repairs .

Is the repair complete?

Go to Step 12

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8

Repair the open, high resistance or short to ground in one of the following circuits. Refer to Wiring Repairs .

    • Battery positive voltage
    • Stop lamp switch signal
    • Lamp supply voltage

Is the repair complete?

Go to Step 12

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9

Repair one of the following conditions. Refer to Wiring Repairs .

    • An open, high resistance or short to ground in the lamp supply voltage circuit.
    • An open or high resistance in the ground circuit.

Is the repair complete?

Go to Step 12

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10

Replace the inoperative bulb, high mounted stop lamp assembly, or tail lamp printed circuit. Refer to Tail Lamp Bulb Replacement , High Mount Stop Lamp Replacement , or Tail Lamp Circuit Board Replacement .

Is the repair complete?

Go to Step 12

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11

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

Did you complete the repair?

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