For 1990-2009 cars

### Diagnostic Aids

In a vehicle equipped with a sunroof, the interior courtesy lamps is near the rearview mirror and also serves as a map lamp. In a non-sunroof vehicle, the interior courtesy lamp is in the roof in the middle of the passenger compartment. There are separate map lamps near the rearview mirror. There is a timer in the interior courtesy lamp that will only supply a ground to the key illumination lamp for a few seconds after the door is opened and closed.

### Test Description

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

1. The resistance of the key illumination bulb and attached harness is approximately 14.1 ohms.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 |

1. Set the switch on the courtesy lamp so that it comes ON when a door is opened.
2. Inspect the function of the courtesy lamp.

Is the courtesy lamp operating?

--

Go to Step 3

Go to Step 2

2 | Repair the interior courtesy lamp system. Does the key illumination lamp function? | -- | System OK | Go to Step 3
3 |

1. Remove the lower steering column cover to gain access to the connectors for the ignition switch.
2. Disconnect the connector to the key illumination lamp.
3. Measure the voltage at terminal 1 of the key illumination lamp connector.

Is the voltage within the specified range?

11-14 V

Go to Step 5

Go to Step 4

4 | Repair the open circuit between fuse EF11 and the ignition key illumination lamp connector. Is the repair complete? | -- | System OK | --
5 |

1. Remove the key illumination lamp and the attached wires and connector.
2. Use a vehicle battery and jumper wires to directly power the illumination lamp through its attached connector and wires.

Does the key illumination lamp turn ON when it is directly connected to power and ground from a battery?

--

Go to Step 9

Go to Step 6

6 | Inspect the key illumination lamp bulb. Is the bulb defective? | -- | Go to Step 7 | Go to Step 8
7 | Replace the key illumination lamp bulb. Is the repair complete? | -- | System OK | --
8 | Replace the lamp socket and the attached wires and connector. Is the repair complete? | -- | System OK | --
9 |

1. Remove the courtesy lamp.
2. Disconnect the electrical connector of the courtesy lamp.
3. Connect an ohmmeter between key illumination connector terminal 2 and ISU connector terminal B11.

Does the ohmmeter indicate the specified value?

0 ohms

Go to Step 11

Go to Step 10

10 | Repair the open circuit between the key illumination connector and the ISU connector. Is the repair complete? | -- | System OK | --
11 | Replace the courtesy lamp. Is the repair complete? | -- | System OK | --