Dome light and stereo not working

[megerian]

I recently acquired an '88 M491 Cabriolet. The PO had it stored for a while, on a battery tender. For storage, he had someone disconnect/disable the trunk light, and the stereo, presumably to not draw power during long storage periods, and because the trunk lid would be partially open to accommodate the battery tender.

He admitted he wasn't sure how it was disconnected, and since I liked the car a lot, this wasn't a deal breaker. I see now that the dome light and glove box light also do not come on. I connected a small led tester to the contact points on the dome light and get nothing. Is it possible that in the process of disconnecting the stereo, this also disconnected the dome light and some other lights? The filament in the dome light bulb is intact and the stereo is fairly new, so I don't think that all these items have failed.

Note that the blinkers, power windows, power mirrors, indicator lights, dash lights, and most everything else is working. Fuses look fine. Any suggestions?

[megerian]

I also see that in the Bentley manual, it shows that Panel #1, Fuse1:

Clock
Glove compartment light, Interior light
Luggage compartment light
Radio

all of which have no power, fuse is intact... any suggestions on what to check next? Forgive me, I am new at this.

thanks, Mark

[ossiblue]

In your first post you didn't mention the clock but I assume, from the second post, that it also doesn't work. If that's the case, the problem is likely at the fuse block as you suspect.

Just because a fuse looks good doesn't mean it is or that good contact is being made. If you haven't done so, remove the fuse, clean the terminals and fuse ends and reinstall. If that fails to provide power, use your test light. Power should be coming from the top wire of terminal 1 or the top terminal, at least. Use your test light and connect it to the bottom terminal. If it lights, the fuse is good. If it doesn't light, either the fuse is bad or no power is coming to the fuse from the top terminal. If that's the case, swap out a known good fuse and repeat.

If it still doesn't light, repeat the test from the top terminal. If no light, check the power from the wire itself (be careful, it's a constant "hot" wire.) If no light from the wire, trace it back to the battery, looking for breaks or disconnections. Also, some terminals on the fuse block are connected to the one next to it by a "jumper" behind the block itself so there is no wire connected to the top screw. I don't know if terminal 1 has such a set up but if you don't see a wire screwed into the top terminal, it means power is being supplied by the adjacent terminal through the back of the block. It's not likely that jumper is bad, but it is a remote possibility.

If the above tests show power at the fuse block and through the fuse, then the problem is along the wiring to the devices.

[megerian]

Thanks for the great suggestions. If you were going to intentionally disconnect the radio, lights, etc. to prepare for storage, where would you have disconnected it?

[porschenut]

Originally Posted by megerian

If you were going to intentionally disconnect the radio, lights, etc. to prepare for storage, where would you have disconnected it?

At the battery negative post. No reason to keep the fuse block powered during storage.

[ossiblue]

Originally Posted by porschenut

At the battery negative post. No reason to keep the fuse block powered during storage.

+1. Simplest place. Check your wiring diagram and see if fuse 1 is a separate wire directly to the battery.

[megerian]

Update: it was the fuse, once it was taken out and replaced, I got a working dome light, glovebox light, trunk compartment light and the faceplate of the radio lit up. Strangely, the horn started making a buzzing sound as soon as I put the key in the ignition. Then I turned the dome light on and off a few times and the buzzing stopped. (?)

The saga isn't completely over, though, since the radio makes no sound. I see a separate cable coming of the battery post, into a fuse, and into an aftermarket amplifier in the luggage compartment. No power to the amp, perhaps another bad fuse...

thanks for the all help - this forum is awesome.