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

Place the headlamp switch in the PARK position.

Do the park, license, and tail lamps illuminate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Are all park, license, and tail lamps inoperative?

Go to Step 6

Go to Step 4

4

Test the supply circuit of the inoperative lamp for high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 5

5

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

Did you find and correct the condition?

Go to Step 18

Go to Step 14

6

Using a scan tool, command the park lamps ON.

Do the park lamps illuminate as expected?

Go to Step 7

Go to Step 8

7

  1. Disconnect the headlamp switch connector.
  2. Connect a fused jumper wire between the park lamp switch ON signal circuit of the connector and ground.

Do the park lamps illuminate?

Go to Step 11

Go to Step 13

8

  1. Remove the park lamp relay.
  2. Install a fused jumper between the battery positive voltage circuit and the park lamp supply voltage circuit of the park lamp relay.

Do the park lamps illuminate?

Go to Step 10

Go to Step 9

9

Test the park lamp supply voltage circuit for high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 12

10

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

Did you find and correct the condition?

Go to Step 18

Go to Step 15

11

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

Did you find and correct the condition?

Go to Step 18

Go to Step 16

12

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 18

Go to Step 17

13

Repair the park lamp switch ON signal circuit for high resistance or an open. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 10

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14

Replace the inoperative bulb.

Did you complete the replacement?

Go to Step 18

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15

Replace the park lamp relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 18

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16

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the replacement?

Go to Step 18

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17

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 18

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18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3