GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Place the ignition switch in the RUN position.
  2. Observe the stop lamps.
  3. Press and release the brake pedal.

Do the stop lamps operate properly?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Is only one stop lamp inoperative?

Go to Step 6

Go to Step 4

4

  1. Disconnect the stop lamp switch.
  2. Using a test lamp connected to ground, probe the battery positive voltage circuit of the stop lamp switch connector.

Does the test lamp illuminate?

Go to Step 5

Go to Step 10

5

Install a fused jumper between the battery positive voltage circuit and the stop lamp switch signal circuit of the stop lamp switch connector. Refer to Circuit Testing in Wiring Systems.

Do the stop lamp illuminate?

Go to Step 11

Go to Step 13

6

Are the tail lamps inoperative?

Go to Step 7

Go to Step 8

7

  1. Remove the inoperative tail lamp bulb.
  2. Using a test lamp, probe between the stop lamp switch signal circuit and ground circuit of the inoperative tail lamp bulb socket.

Does the test lamp illuminate?

Go to Step 19

Go to Step 8

8

  1. Disconnect the inoperative tail lamp assembly connector or center high mounted stop lamp connector (CHMSL).
  2. Using a test lamp connected to ground, probe the stop lamp switch signal circuit of the tail lamp or CHMSL connector.

Does the test lamp illuminate?

Go to Step 9

Go to Step 16

9

Using a test lamp, probe between the stop lamp switch signal circuit and the ground circuit of the tail lamp or CHMSL connector.

Does the test lamp illuminate?

Go to Step 12

Go to Step 15

10

Test for an open or high resistance in the battery positive voltage circuit of the stop lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 14

11

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 in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 18

12

Inspect for poor connections at the harness connector of the tail lamp assembly or CHMSL. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 17

13

Repair a open, high resistance or short to ground in the stop lamp switch signal circuit of the stop lamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 20

--

14

Repair a short to ground in one of the following circuits:

    • The battery positive voltage circuit of the stop lamp switch
    • The stop lamp switch signal circuit

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 20

--

15

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

Is the repair complete?

Go to Step 20

--

16

Repair a open or high resistance in the stop lamp switch signal circuit of the inoperative stop lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 20

--

17

Replace the inoperative tail lamp or CHMSL. Refer to Tail Lamp Assembly and /or Backup, Sidemarker, Stop, Turn Signal Bulb Replacement or High Mount Stop Lamp Replacement .

Did you complete the repair?

Go to Step 20

--

18

Adjust or replace the stop lamp switch. Refer to Stop Lamp Switch Replacement .

Is the repair complete?

Go to Step 20

--

19

Replace the inoperative stop lamp bulb.

Did you complete the repair?

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2