GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

  1. Place the headlamp switch in the PARK position.
  2. Remove the taillamp relay.
  3. Connect a test lamp between terminal 85 and terminal 86 in the taillamp relay socket.

Does the test lamp light?

--

Go to Step 2

Go to Step 3

2

Connect a test lamp between terminal 30 and terminal 86 in the taillamp relay socket.

Does the test lamp light?

--

Go to Step 4

Go to Step 5

3

Connect a test lamp between the taillamp relay socket terminal 85 and the chassis ground.

Does the test lamp light?

--

Go to Step 6

Go to Step 7

4

Connect a test lamp between terminal 30 and terminal 87 in the taillamp relay socket.

Does the test lamp light?

--

Go to Step 8

Go to Step 9

5

Repair the open CKT 91 (GRN) between terminal 30 in the taillamp relay socket and S232.

Is the repair complete?

--

System OK

--

6

  1. Keep the headlamp switch in PARK.
  2. Connect a J 39200 between terminal 86 in the taillamp relay socket and the chassis ground.

Does the DMM indicate continuity?

--

Go to Step 10

Go to Step 11

7

Repair the open in CKT 91 or CKT 93 (GRN) between Circuit Breaker #19 and the taillamp relay socket terminal 85.

Is the repair complete?

--

System OK

--

8

Replace the taillamp relay.

Is the repair complete?

--

System OK

--

9

Repair the open in CKT 94 (BRN) between S321 and the taillamp relay socket terminal 87.

Is the repair complete?

--

System OK

--

10

Replace the taillamp relay.

Is the repair complete?

--

System OK

--

11

  1. Disconnect the headlamp switch harness connector.
  2. Connect a J 39200 between terminal 2 on the headlamp switch connector and terminal 86 in the taillamp relay socket.

Does the DMM indicate continuity?

--

Go to Step 12

Go to Step 13

12

Replace the headlamp switch.

Is the repair complete?

--

System OK

--

13

Repair the open CKT 85 (GRN/WHT) between terminal 2 in the headlamp switch and terminal 86 in the taillamp relay socket.

Is the repair complete?

--

System OK

--