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

Warning: Do not connect a jumper cable directly to the negative terminal of a discharged battery to prevent sparking and possible explosion of battery gases.

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 inspections?

--

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. Test fuse EF22.

Is fuse EF22 open?

--

Go to Step 4

Go to Step 5

4

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

Is the repair complete?

--

System OK

--

5

Test fuse EF22.

Does the voltage at fuse EF22 equal the specified value?

11-14 V

Go to Step 7

Go to Step 6

6

Repair the open power supply circuit for fuse EF22.

Is the repair complete?

--

System OK

--

7

  1. Disconnect the interior courtesy lamp electrical connector.
  2. Measure 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 EF22 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 measure the resistance between the ground and the courtesy lamp ground terminal of the interior courtesy lamp connector, harness side.

Does the ohmmeter indicate continuity?

--

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

--