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1993 BX16v instrument panel lights not working

Posted: Wed Apr 02, 2014 10:19 am
by michael16v
I have noticed a few nights ago that I have lost the lighting to the LHS of my instrument panel. RHS is working fine.
Not just one or two bulbs but the whole lot.
Looking at the Haynes book of fairy tales wiring diagram only shows the power into a line of light bulbs through to the earth. I have power at the wire shown in the Cct diagram, and an earth.
What I need is a Cct diagram for the instrument panel - anyone got one??
I have checked the earth point on the steering column; its OK. I have even added an extra main body earth lead.
Nothing appears to be unplugged; but it is a bit hard trying to look under the dash. I have removed and bypassed the dimmer. The dimmer works for the RHS of the instrument panel and the heater/cigarette/clock etc. There are no blown fuses. I have removed and refitted all the milti plugs, and checked the bulbs for continuity.
Main worry is that this is the speedo side; as well as the fuel gauge and oil pressure.
Got me stuffed I figure it will be a disconnected/lose wire as it just happened.

Posted: Thu Apr 03, 2014 9:11 pm
by jayw
As far as i remember, they are all fed from one circuit together.

Have you checked the copper tracks on the back of the binnacle aren't broken/detriorated?

Perhaps check for continuity from the input plug to the track at each bulb? Particularly if you have a string of them out.

Posted: Thu Apr 03, 2014 11:54 pm
by michael16v
Well I have fixed it. A long'ish story, so read on if you are interested.
First up it was me who most probably caused the problem in the beginning. I had the instrument panel and under dash wires out/disturbed when chasing a oil pressure gauge and cruise control problem.
So; I have a spare instrument panel and as I was not getting anywhere with the Haynes manual I decided to start using the spare as a test unit. First I removed all the bulbs from the test panel. Then I shone a small torch into each bulb hole and noted where the "lighted" area was. Now this may seem a funny thing to do - surely the bulb shines straight to the front. No. There are "light baffles" inside the panel that direct the light to various areas. Also there are some bulb spots blanked off, or not used. Anyway I found out the bulb locations for the panel lighting. Then I looked at the printed Cct boards - BOARDS! There are 3 overlayed on each other. To get to this Cct board and 2 of the bulbs out, you have to remove another small box from the back of the panel. It has a 3 pin plug on the outside and a 6 pin one underneath so care is needed on removal. Now, as I had found the lighting bulb locations I knew which Cct board powered the bulbs, and was able to trace it back to a plug. It is the one shown in the Haynes manual - imagine that
Having gleaned all this from the test instrument panel I went back to the car. I am now very adept at removing the instrument panel from a BX. In fact this can be done without fully removing the panel. Just disconnect and tilt it back. So I removed the bulbs and tested them. WELL. The ones on the LHS were all blown I tested the power at all the bulb points on the Cct board and the earth on the earth side. All good. So I replaced the 4 blown bulbs and it all works.
Why did all 4 blow at once - would not have a clue. I think I did/shorted something when I was working in that area last week. Actually do not care as it is now fixed and I have gained a lot of knowledge on the way it is layed out and now consider myself an expert on BX instrument removal.
There, told you it was long - ish

Posted: Fri Apr 11, 2014 5:35 am
by frog
Thanks for the update Michael. I've just had mine out, the whole dash actually, swapped it for one from a spare car that had much less cracks. Did you fix your oil pressure gauge? Usually it's the sender.

Posted: Sun Apr 20, 2014 9:49 am
by michael16v
I fitted a mechanical gauge as a checking device. The electrical gauge is reading low, but uniformly low :?: I have fitted new earths and checked the wires - no result.
I am happy that there is good pressure so will live with it?
P.S. The engine now has 500+km on it and is freed up nicely :D It is very quick to rev out to the limiter - 7400rpm - in 2nd and 3rd. I am pleased with the result. Now for the winter project - maybe work the spare head with big valves and some porting :evil: , just because I can lol