GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Exterior Lights Diagnostic System Check?

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Go to Step 2

Go to Exterior Lights System Check

2

  1. Install the scan tool.
  2. Establish communication with the BCM.
  3. Inspect for any current or history DTCs.

Are there any current or history DTCs present?

--

Go to Diagnostic Trouble Code (DTC) List/Type in Body Control System

Go to Step 3

3

  1. Use the scan tool in order to turn on the exterior lamps.
  2. Select PARK LAMPS from the Light Test Menu under Special Functions on the scan tool.
  3. With the ignition on, press the ON button and the OFF button on the scan tool in order to turn the park lamps on and off.
  4. Monitor the scan tool while pressing the ON and OFF buttons. The scan tool can tell you the status of the BCM when either the ON or OFF button has been pressed.

Do the park lamps turn ON when commanded by the BCM?

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Go to Step 11

Go to Step 4

4

  1. Remove the park lamp relay from the relay box.
  2. Use the DMM in order to measure the voltage between terminal 5 of the park lamp relay connector and a known good ground.

Does the voltage measure near the specified value?

B+

Go to Step 6

Go to Step 5

5

  1. Locate an open or a high resistance in CKT A813.
  2. Repair the open or the high resistance in CKT A813.

Did you complete the repair?

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Go to Step 19

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6

  1. Install the park lamp relay K130.
  2. Remove fuses #23, #26 and #30 from the fuse block.
  3. Turn on the ignition.
  4. Turn the headlamp switch to the PARK position.
  5. Use the DMM in order to measure the voltage between the input side of each fuse and a known good ground.

Is the voltage for all three measurements near the specified value?

B+

Go to Step 7

Go to Step 8

7

  1. Inspect for an open fuse. If the fuse is open, replace it.
  2. Also inspect the fuse block for loose or poor connections.

Did you complete the repair?

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Go to Step 19

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8

  1. Remove the park lamp relay K130 from the relay box.
  2. Use the DMM in order to measure the resistance between terminal 4 of the park lamp relay connector and the input side of each fuse.

Is the voltage for all three measurements less than the specified value?

5 ohms

Go to Step 10

Go to Step 9

9

  1. Locate an open or a high resistance in CKT RU812, RU813, RU814 and/or RU815.
  2. Repair the open or the high resistance in CKT RU812, RU813, RU814 and/or RU815.

Did you complete the repair?

--

Go to Step 19

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10

  1. Locate a short to B+ in CKT XM810 and/or CKT XM815.
  2. Repair the short to B+ in CKT XM810 and/or CKT XM815.
  3. If these circuits are OK, replace the lamp relay K130.

Did you complete the repair?

--

Go to Step 19

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11

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

Does the resistance measure less than the specified value?

5 ohms

Go to Step 13

Go to Step 12

12

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

Did you complete the repair?

--

Go to Step 19

--

13

  1. Disconnect the BCM connector C2.
  2. Use the DMM in order to measure the resistance between terminal D9 of the BCM connector C2 and terminal 7 of the headlamp switch connector.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 15

Go to Step 14

14

  1. Locate an open or a high resistance in CKT AM813 and/or CKT AM899.
  2. Repair the open or the high resistance in CKT AM813 and/or CKT AM899.

Did you complete the repair?

--

Go to Step 19

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15

  1. Connect the BCM connector C2.
  2. Connect the headlamp switch connector.
  3. Turn on the ignition switch.
  4. Turn the headlamp switch to the PARK position.
  5. Use the DMM in order to measure the voltage between terminal D9 of the BCM connector C2 and a known good ground.

Does the voltage measure less than the specified value?

1 V

Go to Step 17

Go to Step 16

16

  1. Locate a short to B+ in CKT AM813 and/or CKT AM899.
  2. Repair the short to B+ in CKT AM813 and/or CKT AM899.
  3. If these circuits are OK, replace the headlamp switch. Refer to Headlamp Switch Replacement .

Did you complete the repair?

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Go to Step 19

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17

  1. Turn the headlamp switch to the OFF position.
  2. Turn the ignition switch to the ON position.
  3. Turn the headlamp switch back to the PARK position.
  4. Use the DMM in order to measure the voltage between terminal C12 and a known good ground.

Does the voltage measure less than the specified value?

1 V

Go to Step 19

Go to Step 18

18

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the repair?

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Step 19

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19

  1. Connect all connectors and components that were previously disconnected.
  2. Verify that the exterior lamps operate properly.

Do the exterior lamps operate properly?

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Go to Exterior Lights System Check

Go to Step 1