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

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Place the headlamp switch in the PARK position.
  2. Place the marker lamp defeat switch in the enable position.

Do the marker lamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Do the park lamps operate properly?

Go to Step 4

Go to Park, License, and Tail Lamps Inoperative

4

  1. Remove the inoperative marker lamp bulb.
  2. Connect a test lamp between the inoperative marker lamp bulb marker lamp supply voltage circuit and inoperative marker lamp bulb ground circuit.
  3. Turn ON the marker lamps.

Does the test lamp illuminate?

Go to Step 14

Go to Step 5

5

Test the marker lamp supply voltage circuit for the following:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 20

Go to Step 6

6

Test the marker lamp ground circuit for high resistance or an open. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 20

Go to Step 7

7

  1. Disconnect the marker lamp relay.
  2. Connect a test lamp between the control circuit of the marker lamp relay and battery positive voltage.
  3. Turn the marker lamp defeat switch ON and OFF.

Does the test lamp turn ON and OFF with the marker lamp defeat switch?

Go to Step 8

Go to Step 10

8

  1. Connect a test lamp between the park lamps supply voltage circuit of the marker lamp relay and ground.
  2. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 9

Go to Step 15

9

  1. Connect a test lamp between the battery positive voltage circuit of the marker lamp relay and a good ground.
  2. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 13

Go to Step 16

10

Test the control circuit of the marker lamp relay for high resistance or an open. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 20

Go to Step 11

11

Test the ground circuit of the marker lamp defeat switch for high resistance or an open. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 20

Go to Step 12

12

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

Did you find and correct the condition?

Go to Step 20

Go to Step 17

13

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

Did you find and correct the condition?

Go to Step 20

Go to Step 18

14

Inspect for poor connections at the inoperative marker lamp bulb. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 20

Go to Step 19

15

Repair the following in the park lamps supply voltage circuit of the marker lamp relay:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 20

--

16

Repair the following in the battery positive voltage circuit of the marker lamp relay:

    • An open
    • A high resistance
    • A short to ground

Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 20

--

17

Replace the marker lamp defeat switch. Refer to Accessory Switch Replacement.

Did you complete the replacement?

Go to Step 20

--

18

Replace the marker lamp relay. Refer to Relay Replacement.

Did you complete the replacement?

Go to Step 20

--

19

Replace the inoperative marker lamp bulb. Refer to Roof Marker Lamp Bulb Replacement and Luminescent Lamp Replacement - Outside Mirror.

Did you complete the replacement?

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