GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

1

Inspect the STOP HAZ fuse.

Is the STOP HAZ fuse open?

--

Go to Step 10

Go to Step 2

2

Use a test lamp in order to backprobe connector C1 of the brake switch connector between terminal A and ground.

Does the test lamp light?

--

Go to Step 3

Go to Step 4

3

  1. Use a test lamp in order to backprobe the brake switch connector between terminal B and ground.
  2. Depress the brake pedal.

Does the test lamp light?

--

Go to Step 5

Go to Step 6

4

Repair the open in CKT 140 between the fuse block and the brake switch.

Is the repair complete?

--

Go to Exterior Lights System Check

--

5

  1. Use a test lamp in order to backprobe the turn/hazard headlamp switch assembly connector C2 terminal A and ground.
  2. Depress the brake pedal.

Does the test lamp light?

--

Go to Step 8

Go to Step 9

6

Inspect the adjustment of the brake switch. If the adjustment is correct, replace the brake switch.

Is the repair complete?

--

Go to Exterior Lights System Check

--

7

Repair the open in CKT 140 between the left IP wiring harness junction block and the brake switch.

Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Exterior Lights System Check

--

8

Replace the turn/hazard headlamp switch assembly.

Is the repair complete?

--

Go to Exterior Lights System Check

--

9

Repair the open in CKT 17 between the brake switch and the turn/hazard headlamp switch assembly. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Exterior Lights System Check

--

10

Test CKT 140 for continuity to ground at terminal A of brake switch .

Is ground present?

--

Go to Step 11

Go to Step 12

11

Repair Short to ground in CKT 140.

Refer to Wiring Repairs in wiring systems.

Is repair complete?

--

Go to Exterior Lights System Check

--

12

Test CKT 17 for continuity to ground.

Is ground present?

--

Go to Step 13

Go to Step 14

13

Repair short to ground in CKT 17.

Refer to Wiring Repairs in wiring systems

Is repair complete?

--

Go to Exterior Lights System Check

--

14

With brake switch pressed, test CKT 17 at terminal B of brake switch for continuity to ground.

Is ground present?

--

Go to Step 15

Go to Step 16

15

Replace brake switch.

Refer to LINK.

Is repair complete?

--

Go to Exterior Lights System Check

--

16

Repair short to ground in CKT 18 or 19.

Is repair complete?

--

Go to Exterior Lights System Check

--