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

Press down the brake pedal.

Do all of the stop lamps illuminate?

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

  1. Disconnect the inoperative stop lamp.
  2. Probe the stop lamp supply voltage circuit of the inoperative lamp with a test lamp that is connected to a good ground.
  3. Press down the brake pedal.

Does the test lamp illuminate?

Go to Step 12

Go to Step 7

5

  1. Disconnect the stop lamp switch.
  2. Probe the battery positive voltage circuit of the stop lamp switch with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 13

6

Connect a 15-amp fused jumper wire between the battery positive voltage circuit of the stop lamp switch and the stop lamp supply voltage circuit of the stop lamp switch.

Do the stop lamps illuminate?

Go to Step 9

Go to Step 8

7

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

Did you find and correct the condition?

Go to Step 16

Go to Step 11

8

Test for an open, high resistance, or short to ground in the stop lamp supply voltage circuit between the stop lamp switch and the body control module (BCM). Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 16

Go to Step 11

9

Inspect the stop lamp switch for proper adjustment. Refer to Stop Lamp Switch Adjustment .

Did you find and correct the condition?

Go to Step 16

Go to Step 10

10

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

Did you find and correct the condition?

Go to Step 16

Go to Step 14

11

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

Did you find and correct the condition?

Go to Step 16

Go to Step 15

12

Repair an open or high resistance in the ground circuit of the inoperative stop lamp. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 16

--

13

Repair an open, high resistance, or short to ground in the battery positive voltage circuit of the stop lamp switch. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 16

--

14

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

Did you complete the replacement?

Go to Step 16

--

15

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

Did you complete the replacement?

Go to Step 16

--

16

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3