GM Service Manual Online
For 1990-2009 cars only

Test Description

The number below refers to the step number on the diagnostic table.

  1. Bulb test. Clip one end of a jumper wire to the negative battery terminal. Clip the other end of the jumper wire onto one end of the bulb. Take the free end of the bulb (the end without the jumper attached) and touch it to the positive battery terminal.

Step

Action

Values

Yes

No

1

  1. Remove the interior courtesy lamp bulb and inspect the filament.
  2. If the filament is not broken, test the bulb using the vehicle’s battery and a jumper wire.

Does the bulb pass the visual and physical checks?

--

Go to Step 3

Go to Step 2

2

Replace the bulb.

Is the repair complete?

--

System OK

--

3

  1. Reinstall the interior courtesy lamp bulb.
  2. Check fuse Ef4 and F3.

Is fuse Ef4 and F3 blown?

--

Go to Step 4

Go to Step 5

4

  1. Check for a short circuit and repair it, if necessary.
  2. Replace the fuse.

Is the repair complete?

--

System OK

--

5

Check fuse F3.

Does the voltage at fuse F3 equal the specified value?

11-14 V

Go to Step 7

Go to Step 6

6

Repair the open power supply circuit for fuse F3.

Is the repair complete?

--

System OK

--

7

  1. Disconnect the interior courtesy lamp electrical connector.
  2. Check the voltage at connector terminal 2.

Does the voltage at connector terminal 2 equal the value specified?

11-14 V

Go to Step 8

Go to Step 9

8

Repair the open circuit between fuse F3 and the interior courtesy lamp terminal 2.

Is the repair complete?

--

System OK

--

9

  1. With the interior courtesy lamp disconnected, turn it to the on position.
  2. Use an ohmmeter to check the resistance between ground and terminal 1 of the interior courtesy lamp connector (harness side).

Is the resistance equal to the specified value?

0 ohms

Go to Step 10

Go to Step 11

10

Replace the interior courtesy lamp switch assembly.

Is the repair complete?

--

System OK

--

11

Repair the ground circuit for the interior courtesy lamp.

Is the repair complete?

--

System OK

--