GM Service Manual Online
For 1990-2009 cars only

Caution: When using an external power source to provide power to a component or circuit, always use a fused jumper wire with the proper amp rating for the component or circuit being tested. Failure to use a fused jumper wire may result in accidental overload and may cause personal injury or damage to the component or circuit.

Test Description

The numbers below refer to the step numbers 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

Schematic Reference: Interior Lights Schematics Interior Lights Dimming Schematics

Connector End View Reference: Component Connector End Views

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 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.

Did you complete the replacement?

--

System OK

--

3

  1. Reinstall the interior courtesy lamp bulb.
  2. Inspect fuse EF19.

Is fuse EF19 open?

--

Go to Step 4

Go to Step 5

4

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

Did you find and correct the condition?

--

System OK

--

5

Test fuse EF19.

Does the voltage at fuse EF19 measure within the specified range?

11-14 V

Go to Step 7

Go to Step 6

6

Repair the open power supply circuit for fuse EF19.

Did you complete the repair?

--

System OK

--

7

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

Does the voltage at connector terminal 1 measure within the specified range?

11-14 V

Go to Step 8

Go to Step 9

8

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

Is the resistance equal to the specified value?

0 Ω

Go to Step 10

Go to Step 11

9

Repair the open circuit between fuse EF19 and the interior courtesy lamp terminal 1.

Did you complete the repair?

--

System OK

--

10

Replace the interior courtesy lamp switch assembly.

Did you complete the replacement?

--

System OK

--

11

Repair the ground circuit for the interior courtesy lamp.

Did you complete the repair?

--

System OK

--