'87 735 instrument problems

hi guys, after lurking a while I now need some help. My '87 735 has developed a problem with the gauge cluster. The gas, temp, tach and economy gauges have failed. The gas and temp sit at approx 1/4, dropping to zero when key is turned off. Tach and economy are dead. I noticed this yesterday when towing my racecar (which uses normnal trailer plug for auxilary lights). Any chance the problem is related? Is this a common fault with a known fix? thanks

hi guys, after lurking a while I now need some help. My '87 735 has developed a problem with the gauge cluster. The gas, temp, tach and economy gauges have failed. The gas and temp sit at approx 1/4, dropping to zero when key is turned off. Tach and economy are dead. I noticed this yesterday when towing my racecar (which uses normnal trailer plug for auxilary lights). Any chance the problem is related? Is this a common fault with a known fix? thanks

This sort of problem is usually 'capacitor' related and can be pretty easily fixed if you have time patience and are any good with a soldering iron. The capacitors are behind the dash and this has to be removed to replace them. They only cost cents and can be replaced entirely. At least you will have eliminated one likely cause, for pennies. Another thing worth looking at is any multi pin plugs and sockets connected to the back of the dash. These should be inspected and cleaned with an electrical contact cleaner. I'd imagine towing a trailer is just an unfortunate coincidence, but could stand corrected. Of course, very first thing to do is check all fuses, both under the bonnet and under the back seat beside the battery.
Hope this helps.

Don't know if the 1987 and 1988 735i and iL are the same. I was just telling Liberty. The Signal light, hazards, fasten seat belt, and all indicators is called the Cluster in the outside world.

i have this for my 88 735iL cluster assembly

part# 110 008 7G60 /040

1 388 083 9

12V
K=7295

VDO 88311 111

My automatic Tilt wheel on the steering wheel does not work so they had to take the Streering wheel apart then replace it.

SO it works but when I hit a bump the engine power almost cuts of but most of the time it works. SO THIS IS YOUR SOLUTION change the cluster.

OK good luck. The cluster when installed properly works good. I'm taking mine back tomorror to tighten.

ok, so we jiggled all the fuses etc, and failure was still present. However, 2 days later all gauges started working :-) How long for though? :-/

Does the fact the fault is erratic make any diagnosis easier?