GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

1

Did you review the Lighting System Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Lighting Systems

2

Verify that the park lamps are inoperative.

Does the system operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn the ignition switch to the ON position.
  2. Place the headlamp switch in the ON position.
  3. Use a test lamp to check junction block 2, C3 cavity 9 to ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 5

4

Use a test lamp to check junction block 1, C6 cavity 9 to ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 7

5

Connect a test lamp between cavity 3 of the TAIL relay and ground.

Do the park and tail lamps illuminate?

Go to Step 9

Go to Step 8

6

Repair the open in the GRN wire between the junction block 1, C6 cavity 9 and the junction block 2, C3 cavity 9. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

Go to Step 14

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7

Replace junction block 1.

Is the replacement complete?

Go to Step 14

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8

Replace the TAIL Relay.

Is the replacement complete?

Go to Step 14

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9

Test for high resistance between cavity 6 of connector C3 of junction block 2 and cavity 16 of the DRL control module connector .

Is there high resistance in the LT GRN wire?

Go to Step 10

Go to Step 11

10

Test for high resistance between cavity 14 of the turn/signal/headlamp switch connector and cavity 17 of the DRL control module connector.

Is there high resistance in the LT GRN/BLK wire?

Go to Step 13

Go to Step 12

11

Repair the open in the LT GRN wire between cavity 6 of connector C3 of junction block 2 and cavity 16 of the DRL control module connector . Refer to Wiring Repairs in Wiring Systems.

Is the replacement complete?

Go to Step 14

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12

Repair the open in the LT GRN/BLK wire between cavity 17 of the DRL control module connector and cavity 14 of the turn signal/headlamp switch. Refer to Wiring Repairs in Wiring Systems.

Is the replacement complete?

Go to Step 14

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13

Replace the DRL module. Refer to Daytime Running Lights (DRL) Control Module Replacement .

Is the replacement complete?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3