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 in Vehicle DTC Information

2

Verify that the turn signal lamps and/or indicators are always ON or flashing.

Do the turn signal lamps operate normally?

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

Go to Step 3

3

Inspect the affected bulb/socket for an internal short, poor terminal contact, or a shorted filament.

Was a problem found?

Go to Step 8

Go to Step 4

4

Disconnect the multifunction turn signal switch.

Do the affected turn signals and indicators still illuminate?

Go to Step 5

Go to Step 6

5

Test for a high resistance or short to ground in the turn signal switch signal circuit.

Did you find and correct the condition?

Go to Step 11

Go to Step 7

6

Inspect for poor connections at the multifunction turn signal switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

7

Inspect for poor connections at the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

8

Replace or repair the affected bulb/socket. Refer to Headlamp Assembly or Headlamp Bulb and/or Cornering, Sidemarker, Park, Turn Signal Bulb Replacement or Tail Lamp Assembly and /or Backup, Sidemarker, Stop, Turn Signal Bulb Replacement .

Did you complete the repair?

Go to Step 11

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9

Replace the turn signal/multifunction switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the repair?

Go to Step 11

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10

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the repair?

Go to Step 11

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11

  1. Use the scan tool in order to clear any induced DTCs.
  2. Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3