GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Headlight Diagnostic System Check?

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Go to Step 2

Go to Headlight System Check

2

  1. Turn on the low beam headlamps.
  2. Disconnect the turn signal switch connector.
  3. Use the DMM in order to measure the voltage between terminal 1 of the turn signal switch connector and a known good ground.

Is the measured voltage within the specified value?

B+

Go to Step 4

Go to Step 3

3

  1. Locate an open or a high resistance in circuits B905 and/or B800.
  2. Repair the open or the high resistance in circuits B905 and/or B800.

Did you complete the repair?

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Go to Step 6

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4

  1. Connect the turn signal switch connector.
  2. Disconnect the BCM connector C1.
  3. Turn the high beam switch to the ON position.
  4. Use the DMM in order to measure the voltage between terminal A4 of the BCM connector C1 and a known good ground.

Is the measured voltage within the specified value?

B+

Go to Step 6

Go to Step 5

5

  1. Locate an open or a high resistance in circuits  M3 and/or M50.
  2. Repair the open or the high resistance in circuits M3 and/or M50.
  3. If these circuits are OK, replace the turn signal switch. Refer to Turn Signal Switch Replacement - On Vehicle in Steering Wheel and Column On Vehicle Service.

Is the repair or replacement complete?

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Go to Step 6

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6

  1. Connect all connectors and components that were disconnected.
  2. Verify that the high beam headlamps operate properly.

Do the high beam headlamps operate properly?

--

Go to Headlight System Check

Go to Step 1