GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Upfitter Provision 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

Verify that the roof beacon lamp is inoperative.

Does the roof beacon lamp operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Place the roof beacon switch in the ON position.
  2. Connect a test lamp between the power and ground circuits of the roof beacon lamp connector.

Does the test lamp illuminate?

Go to Step 8

Go to Step 4

4

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

Did you find and correct the condition?

Go to Step 11

Go to Step 5

5

  1. Remove the roof beacon switch.
  2. Place a fused jumper between the hazard switch signal and battery positive voltage circuits of the roof beacon switch connector terminals.

Does the roof beacon lamp illuminate?

Go to Step 9

Go to Step 6

6

Test the following circuits for a high resistance, open or a short to ground:

    • Battery positive voltage circuit of the switch
    • Battery positive voltage circuit of the relay
    • Hazard switch signal circuit of the relay
    • Hazard flasher signal circuit of the relay

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 7

7

Test the ground circuit of the roof beacon relay for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

8

Replace the bulb or lamp assembly. Refer to upfitter instructions.

Did you complete the replacement?

Go to Step 11

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9

Replace the roof beacon switch.

Did you complete the replacement?

Go to Step 11

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10

Replace the roof beacon relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 11

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11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3