There are three connection points on the roof light. These points are for:
* Power - Red Wire - goes to the end of bulb with a single connection (Non-switched). There should always be 12v on this wire.
* Switched Ground - Brown w/ White stripe Wire - Goes to one of the switch connections on other end of bulb. This wire should be grounded ONLY when a door or the hatch is open.
* Nonswitched Ground - Brown Wire - Goes to the other connection on the switch in the light and to a body ground point. This wire should always be grounded.
Operation of Light:
There is always 12v on one end of the bulb.
The light switch in the light is operated by rotating the light lens up and down to one of three positions - off, on, and automatic.
When all doors and the hatch are closed and the switch is in the automatic position - light should be off because there is no ground through the door switches, even though the brown/white wire is connected
to the bulb.
When a door or the hatch is opened, the door/hatch switch connects the brown/white wire to ground, and the light comes on.
When all doors and the hatch are closed and the switch is in the on position - light should be on because the switched end of the bulb is hooked to the brown ground wire.
When the light switch is in the off position, the light should always be off, because the switch prevents connection to any ground.
Tests:
Check the bulb by resistance or by applying 12v or by substitution.
Check for 12v on the red wire - should always have 12v.
Check for ground on the brown wire - should always have ground.
Check for ground on the brown/white wire - should have ground only when a door or the hatch is open. Check each door and the hatch separately.
Wally Plumley
928 Specialists
