Bizzare Interior Light Problem

[Jberger]

Well, I guess I talked too good about my 90 Q today, it's flaking out on me tonight.

Here's the deal. Today, I started getting the "stop light inoperative" message this afternoon. Tonight, I flip on the headlights and the dash does not light up!

Turned the car and lights off.

Restarted and turned the lights back on, still no dash lighting, not on the gauges, radio, switches, anything. UNLESS, I step on the brakes, then they all light up as normal.

There is no problem with the headlights and no tailights are out as far as I can tell. Since the car was just at the dealer yesterday, I'm thinking is a loose wire or perhaps a relay.

Any ideas appreciated!

[Q451990]

It may be a blown fuse... had the same problem on my Q. Check the tail light sockets for corrosion and melting on the lead tips on the bulbs. Very common problem with an easy solution. Clean the socket assemblies (or just replace at less than $20 each from Joe) and use OEM bulbs.

Heath

[Q451990]

Just re-read your post... didn't have stuff come back on with the brake lights, but I'd still check the socket assemblies. Maybe something is back-feeding through the shift-lock solenoids?

Heath

[Jberger]

Well, I've pulled the rear bulbs and the passenger side sockets were fairly corroded. Cleaned the sockets but haven't reinstalled the bulbs.

Now the interior lights will not turn on at all. Regardless if the brakes are on or not. Any idea which relay might be a contributor?

[Jberger]

Bump.

Anyone, Bueller?

[Jberger]

Final resolution: (Just in case anyone else ever has a similar issue)

I changed all the rear bulbs, the brake lights worked but they didn't come on with the headlights. None of the dash lighting worked either, but would occasionally come on when I pressed the brakes. Checked ALL fuses and relays, everything tested fine.

But the problem remained. Decided to just change the fuses, and THAT solved the problem. Appearntly the 10A brake lamp fuse was partially burnt, There was enough current to show continuity with a multimeter, but not enough to actually power the lights. Wierd but true!

YMMV

[Q451990]

Wow! Thanks for the update! Did you happen to check the resistance of the fuse and compare it with another one?

I once took a light bulb out of my girlfriends car that had gotten so hot that the glass melted and created a bubble in the side of the housing... sometimes things just don't burn out that are supposed to!

Heath

[expertie]

I really enjoy and benefit from here.I had this same problem with my J30. It happened once months ago and lasted 15 seconds. I thought it was just ok.Last night, it happened again and I decided to check these forums. As said, the brake light (tail light) fuse 7.5A was half-burned. I replaced it and it is back again.Hope this helps.

[maxnix]

As said, the brake light (tail light) fuse 7.5A was half-burned. I replaced it and it is back again.

Check your sockets! Something caused it to be half-burned.

[Q45tech]

Aftermarket bulbs are mostly junk [even BIG name brand ones] and don't fail the EXACT same way as oem Hitachi........just change all the 8 rear bulbs frequently [every 2 years] and check sockets closely.

After market bulbs and fuses cause so many problems...........in 14 years only one fuse has blown [when the condenser fan failed]. I'm on my 3rd set of rear bulb sockets. Because I can't get Hitachi bulbs...........Sylvania LL [LL stands for Long Life] are the only ones I use now, not as good but better than anything commonly available.

$8 every 2 years sure beats replacing the sockets frequently.

Have seen 4-5 rear upper brake light assemblies totally melted inside from aftermarket junk bulbs.