GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Headlight Diagnostic System Check?

--

Go to Step 2

Go to Headlight System Check

2

  1. Disconnect the headlamp switch connector.
  2. Use the DMM to measure the resistance between terminal 13 of the headlamp switch connector and a known good ground.

Is the measured resistance less than the specified value?

5 ohms

Go to Step 4

Go to Step 3

3

  1. Locate an open or a high resistance in circuit F18.
  2. Repair the open or the high resistance in circuit F18.

Is the repair complete?

--

Go to Step 11

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4

  1. Connect the headlamp switch connector.
  2. Disconnect the BCM connector C2.
  3. Turn the headlamp switch to the HEAD position.
  4. Use the DMM to measure the resistance between terminal D10 of the BCM connector C2 and a known good ground.

Is the measured resistance less than the specified value?

5 ohms

Go to Step 6

Go to Step 5

5

  1. Locate an open or a high resistance in circuits B899 and/or B60.
  2. Repair the open or the high resistance in circuits B899 and/or B60.
  3. Replace the headlamp switch if these circuits are OK. Refer to Headlamp Switch Replacement in Instrument Panel, Gauges and Console.

Is the repair or replacement complete?

--

Go to Step 11

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6

  1. Disconnect the low beam relay K131 connector.
  2. Use the DMM to measure the voltage between terminal 5 of the low beam relay K131 connector and a known good ground.

Is the measured voltage within the specified value?

B+

Go to Step 8

Go to Step 7

7

  1. Locate an open or a high resistance in circuit A814.
  2. Repair the open or the high resistance in circuit A814.

Is the repair complete?

--

Go to Step 11

--

8

Connect a fused jumper between terminals 4 and 5 of the low beam relay K131 connector.

Do the low beam headlamps turn ON?

--

Go to Step 10

Go to Step 9

9

  1. Locate an open or a high resistance in circuit B50.
  2. Repair the open or the high resistance in circuit B50.

Is the repair complete?

--

Go to Step 11

--

10

Replace the low beam relay K131.

Is the replacement complete?

--

Go to Step 11

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11

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

Do the low beam headlamps operate properly?

--

Go to Headlight System Check

Go to Step 1