Chris Buckenham

Hello Everybody ,

Having searched previous threads we are struggling with the lighting circuit / hatch release on the 90GT .

Whilst tracking down a 0.4 amp battery draining current draw we decided to get the rear hatch release working and the lighting circuit to function properly . The front interior light had fallen apart and I had a new one which was not fitted .

At present all the lights work in the permanently on mode .

When the front doors are opened the two front door internal lights work and the rear facing door lights work . The timer off function works when the door is closed . Should all the lights in the car come on when either front door is opened or just the door lights ?

When the rear hatch is opened all the lights in the car work and the rear hatch release cycles . The rear hatch release will not work when either of the front doors are opened but the hatch itself is closed . Is this a separate fault or just a symptom of the lighting circuit issues ?

Thanks very much for any help that can be given .

Chris

Bill Ball

All. if they are in the right position. Often they are wired incorrectly or in backwards.

This is the opposite of how it should work. The hatch pull should NOT work with the doors CLOSED, not opened. Are you sure about this? The door pins provide ground to the hatch motor when a door is open.

When do the overhead and hatch lights come on? It is quite common for the lights themselves to fail in the door regulated position.

Tom in Austin

Hi Chris, from your number of posts it appears you may be new, so welcome! The group here on RL can help you figure out these kinds of questions.

Here's a start: if they're wired correctly, yes, the door and two headliner lights come on together when you open a door and then go off on the timer. I believe the hatch light is separate and only comes on when you open the hatch.

You're right, the hatch release is tied into the lighting circuit in order to allow the hatch release to function only with a door open. So yes, a problem in the lighting circuit can cause the hatch release to think the door is open when it's actually closed, or vice versa. Sounds like that may be happening in your case.

Alan

The hatch light is not separate - they all should behave excatly the same (if they are all in the door swithced mode).

Tom - lets not confuse Chris here.

Chris please think and be very concise & precise in what you tell us

I don't think you man what you wrote in your first post...

e.g. "The rear hatch release will not work when either of the front doors are opened but the hatch itself is closed"

I think you mean that the hatch release motor only works when the rear hatch is open. If this is correct what you wrote is not the same thing. Please be very precise on points like this - we cannot help without really accurate info (garbage in garbage out and all that....)

I do think you should take out all the light fixtures and check how they are wired.

Doors & Front Roof - Red wire direct to bulb, Brown wire to ground(frame) and one side of switch, Brown/ White wire to switch only.

Both in Hatch - Green wire direct to bulb, Brown wire to ground(frame) and one side of switch, White wire to switch only.

Alan

Randy V

There is also a light located in the passenger footwell area on the later model years.

Many folks are unaware of this when they buy a car with that bulb burned out.

Bill Ball

Yep. I just fixed that on a 91. The screw that secures this light is inside the glovebox and the light is on the back of the glovebox. Unscrewing it and dropping it down makes bulb replacement much easier.

Chris Buckenham

Thanks for the replies and suggestions. We've followed up on the suggestions and made progress. We haven't tracked the fault down but we're a lot closer.

To clarify the current situation: If a door is opened, the door lights come on. The roof and rear hatch lights do not. When the door is closed, the timer runs and the lights go out after 15 seconds. If the rear hatch is opened, all interior lights come on (rear hatch, roof and doors). When the hatch is closed, the hatch lights and roof light go out immediately but the timer runs and the door lights go out after 15 seconds.

All the individual lights are in good working order, are wired correctly and switched to the correct position. The light units are pulled out of their mountings and dangle on their wires, so there are no shorts to ground.

We experimented with a separate wire connecting the brown/white from a door switch to brown/white at the roof light. The system seemed to work correctly then, with all lights triggered by either door or the rear hatch being opened. Furthermore, the rear hatch pull switch then operates when a door is open, running through a complete cycle when a switch is pulled momentarily.

The connection we made is shown on the 1990 wiring diagram. We checked with a multimeter and the connection is not present on the car at the moment, so we have located a wiring problem. However, having a wire missing doesn't explain why the door lights come on when the rear hatch is opened, so there must have been a modification.

The next task is to trace the wiring in the car and find out exactly what's happened.

Thanks again,

Chris

WallyP

The interior lights are triggered when a door switch or the hatch switch grounds the brown/white wire.

Your problem might be at Connector T10, which is under the trim panel near the post behind the passenger door, or at Terminal U11 (brown/white wire in the bottom left of Plug U on the Central Electric Panel). You can do some testing by using a jumper to ground the brown/white wire at various points and see what happens. Grounding the wire at any point should do the same thing as opening a door or the hatch. I would start by using a thin probe to ground Terminal U11.

Chris Buckenham

Thanks Wally , we will carry out these checks today and see where we get.

Edit: We tried the U11 grounding. That has exactly the same effect as opening a door, the door lights come on and the roof/hatch lights stay off. The timer runs when the wire is removed. We are surprised at this, as it doesn't behave as the wiring diagram suggests it should.

Getting to T10 looks quite a job. Please could you clarify exactly where it is? Do you mean to the rear of the 'B' post? If so, that's a major trim panel to remove. Remembering that this car is a UK RHD car, will it still be the passenger (LH looking forward) side? The CE Panel is on the passenger side, so we expect it will be that side, thinking about it.

Best Regards
Chris.

Alan

Chris I think it will be the passenger side in a RHD also - proximity to the CE as you say.

The interesting thing is that the hatch still controls the doors but not vice versa. Now does the central roof light (between visors) switch with the doors? I assume yes.

Almost seems as if someone added a diode insead of a wire here - however the hatch alone should not trigger the door delay - so thats interesting.

Has anyone added a keyless entry or alarm to this car? if they did and tried to hook up the dome light supervision that could be causing some interesting issues - check for aftermarket connections on the alarm/locking units.

Alan

WallyP

Chris,

Yes, under the passenger side - either right or left drive.

The results of grounding U11 makes the problem interesting. If you look at the wiring diagram, grounding U11 should ground all lights on the brown/white wire.

If the rear lights don't come on, it appears that the brown/white wire is disconnected between U11 and the rear lights.

I see no reason why the timer should run when U11 is grounded. The timer runs when Terminal T on the relay is grounded, and that should happen only when a door switch (not the hatch switch) is grounded.

So, is U11 hooked to Terminal T? If so, AND there is a faulty connection at T10, you might get your results.

Time to do some serious study of the interior light circuit...

dcrasta

Did you resolve this problem? I am having the exact problem.

Lights come one with Hatch open / Go out with Hatch closed.
Door pins do not activate the lights (however the door open w/key in ignition chime comes on).

About to follow the troubleshooting steps that were outlined above.

If you resolve this please update TIA!