Another '90 GT, another dead digi-dash, just like Docmirror's. I was in the driver's door last weekend doing window guides and door stop R&R but then didn't get to drive the car til tonight. No gauges except the voltmeter (tho the oil pressure gauge said 1.5 bar), no digital display at all, ABS light on, no interior lights. When I got to my destination, the red lights in the ends of the doors were out, and when I locked the door the LED's in the lock stems didn't flash. The gauge panel illumination works fine, and dims when the headlights are turned on. It's strange driving without gauges, I had no idea how much I glance down at them.....I guess the moral of the story is to disconnect the battery whenever disconnecting any wiring..... At least the door is vault-like again.

 

Indeed ! but a cheap fix anyway...

Alan

 

I would have thought there was a intermittent (the most beloved fault to chase down) short in one of
both of the ceiling interior light that goes kabloooey whenever car hits a bump.

 

It sounds like you have a serious power drain after your adventure in the door. Get it looked at pronto. In wire looms, the most likely issue is two or more wires touching each other in the loom. This can cause strange and erratic behavior. There are no ground wires in most looms as the chassis and engine act as the ground. Although some small ground lines are present from certain places to a ground point. One of those places is in the door, because there is no reliable ground point in the door. so, the ground lines have to go back to the main chassis for ground IIRC. You could be shorting a wire to a ground line in that door loom. Or, touching another wire in there somewhere.

 

Or could have just shorted the interior light fixture power connection to ground... Since it happend while in the door I'd expect this is most the likely answer

Alan

 

Ruh Roh. Fuse 25 was blown, I replaced it but no joy- the dash and door/interior ligths are still dead. Time to go back into the door to see what I did......

 

Inside lights, Diag connn, Inst cluster. This servers a lot of stuff. 7.5 amp fuse. Sheet 2, grid LM10. Locate connector T10. disconnect it, and start checking resistance on the female connector end. Pay particular attention to pins 4, 5, and 3 as these service the notorious roof lamp which is just above the mirror. This lamp harness has been the source of many electrical faults.

You can also leave T10, T11, T6, T22 disconnected, put in another fuse 25 and then turn the key on. See if the inst cluster lights up properly and goes through it's POST. If so, you have confined the issue to the T10 circuit of interior lights. Note that T11 services the rear set of lights, T6 services the drivers door light and T22 services the pax door light(and the door lock light too). If the fuse is still good, start the car, connect in order: T22, pax door light, T10, roof light, T11, rear lights, then finally T6 drivers door light. If the failure occurs during the pluging of one of these T connectors, that is your fault circuit.

I doubt the diag connn would be source of trouble. If the problem is still there, we have to move on to the inst cluster connnections. Yuch.

 

Doc-

Thanks for the to-do list- will report back with results.

 

I assume the fuse blew again? If so probably worth taking a look at the door again since thats what you were doing when it went out. Inside the door its really only the interior light on this circuit - so pull the light and make sure all the connections are good (red wire dangling against the door?). Easy to check as a first culprit - otherwise Doc's list is good.

Alan

 

if the light isnt causing any problems then then next thing would be the harness just after it enters the door panel (panel needs to be removed) the harness sometimes can rub through on the door or any other part that the harness contacts. Pay close attention to the harness you might find worn through insulation

 

What a timely update of this particular thread!!!! Just got the '89 back on the road and WTF? the digital dash, radio, and mirrors are non-functional. Got to check that fuse 25 and go from there. Thanks Doc et al.

 

Mmmmkay, I am a grade A dumbass. Fuse 25 needs to be a 7.5 on a 1990, not a 5, like I had initially installed. No wonder it blew again. All is good now....

 

ALL is good? Glad to hear that.

 

Pulled the fuse out and checked it. Checks out good and I am thinking WTF? Slide the fuse back in and as it makes contact, the interior lights come on. All is right with the world. Well mostly anyway!

Thanks everybody!!

 

Doc-

Yep, I had first installed a 5A fuse, it must have blown when I lit up all the interior lamps. A 7.5A fuse (the correct rating) cured it.

As an aside, I had done the CE cleaning/Stabilanting back in April 2008 and replaced all the fuses with the kit that MrLexse had been selling. I ran my finger down the line of fuses and discovred that more than a few were not completely seated- I'm certain that I'd seated them completely barely 6 months ago. Yet another argument for WallyP's annual electrical maintenance checks.....