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

Place the marker lamp switch in the OFF position.

Are the marker lamps OFF?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Disconnect the marker lamp relay.

Do the marker lamps remain illuminated?

Go to Step 6

Go to Step 4

4

Probe the marker lamp relay coil side control circuit with a test lamp that is connected to ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 8

5

  1. Leave the test lamp connected.
  2. Disconnect the marker lamp switch.

Does the test lamp remain illuminated?

Go to Step 7

Go to Step 9

6

Repair a short to voltage in the marker lamps voltage supply circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 10

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7

Repair a short to voltage in the marker lamp relay coil side control circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 10

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8

Replace the marker lamp relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 10

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9

Replace the marker lamp switch. Refer to Trailer Marker Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 10

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10

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3