GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Important: The power and ground circuit is common for many lamps. A failure of an individual lamp is usually caused by one of the following conditions:

   • An open in CKT 1220
   • An open in CKT 1050 between S205 and splice pack SP203
   • A bad lamp

1

Did you perform the Interior Lamps Dimming System Check?

--

Go to Step 2

Go to Interior Lights Dimming System Check

2

Is the ILLUM fuse open?

--

Go to Step 3

Go to Step 4

3

Locate and repair a short to ground in CKT 1220 (GRY).

Is the repair complete?

--

Go to Interior Lights Dimming System Check

--

4

  1. Turn the ignition switch to the ON position. Do not start the engine.
  2. Move the headlamp switch to the PARK position.
  3. Using the scan tool, monitor the dimming input from the dimmer switch.
  4. Rotate the dimmer switch between MINIMUM and MAXIMUM.

Does the dimmer input voltage vary within the specified range?

0-11 V

Go to Step 11

Go to Step 5

5

  1. Move the dimmer switch to the MAXIMUM illumination position.
  2. Move the headlamp switch to the PARK position.
  3. Using the J 39200 DMM, backprobe terminal K of the headlamp switch to ground.

Is the voltage within the specified range?

10-11 V

Go to Step 9

Go to Step 6

6

Backprobe terminal B of the headlamp switch to ground.

Is voltage present?

System Voltage

Go to Step 8

Go to Step 7

7

Locate and repair the open in CKT 240 (ORN).

Is the repair complete?

--

Go to Interior Lights Dimming System Check

--

8

Repair or replace the headlamp switch. Refer to Headlamp Switch Replacement .

Is the repair complete?

--

Go to Interior Lights Dimming System Check

--

9

  1. Using the J 39200 DMM, backprobe the body control module (BCM) connector C3 terminal A5 to ground.
  2. Move the headlamp switch to the PARK position.
  3. Move the dimmer switch to the MAXIMUM illumination position.

Is the voltage within the specified range?

10-11 V

Go to Interior Lights Dimming System Check

Go to Step 10

10

Locate and repair an open in CKT 1220 (GRY).

Is the repair complete?

--

Go to Interior Lights Dimming System Check

--

11

  1. Move the headlamp switch to the PARK position.
  2. Move the dimmer switch to the MAXIMUM illumination position.
  3. Using the fused jumper wire, backprobe between splice pack SP203 terminal J and terminal E.

Do the instrument cluster lamps illuminate?

--

Go to Step 12

Go to Step 13

12

Repair or replace splice pack SP203.

Is the repair complete?

--

Go to Interior Lights Dimming System Check

--

13

Locate and repair an open in CKT 1050 (BLK).

Is the repair complete?

--

Go to Interior Lights Dimming System Check

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