E30 Zone

Hi all, I must apologize this mega long post, but this is the best way to describe this cluster issue. I've read various topics and googled a lot about cluster issues, but the common answers have not solved my cluster issues. Everything works as it should even for a week at times. Then temp gauge may start to twitch (little but rapid movement). Now it flickers (still rapid movement, but scale is larger). At the same time consumption gauge may still work. Opposite situation has also occurred. During this, all other gauges work as should. At the moment consumption gauge works and temp gauge twitches. This is a daily driver and there are instances where consumption gauge was not working on evening when car was parked. Then following morning it works!


When consumption gauge is acting oddly, it stays on the far left. I have a liters/km-gauge. So gauge shows zero consumption. Signal of fuel rate may be lost? Is it simple math, 0 fuel rate signal divided by any speed signal results in zero consumption on the gauge? Investigated this problem last week and discovered that when car is not moving but engine is running, if I take coding plug away and then put it back (engine still running), suddenly consumption gauge started working. Rev counter did not die. Consumption gauge would go to far right to between thick white bars as should when not moving. So it worked. Then tried the same thing later when temp gauge started twitching, result was that rev counter and consumption gauge died and inspection lights came on. For some reason removing and reattaching fuse 10 (brand new fuse) and SI reset made them work again. Took apart the coding plug and resolder the joints to check if this may be a connection problem. As mentioned above, now consumption gauge has worked few days.

When problem with temp gauge first started, the needle rose steadily near to center position, usually few millimeters left from center and then it started twitching. Now the situation has worsened, it makes little twitching whole time when needle is rising but still the needle rises near the center position. Then it starts to flicker between dead center and the first white line. So the range of flickering has become larger during time. When starting the car, needle usually rises immediately or within 1-2 seconds on the beginning of the blue/cold area. After some driving when motor should be at normal temp, if park the car and turn off ignition and then turn ignition on but not start the motor, temp gauge may still twitch. When temp gauge works, needle is at exact center position whole time.

Does this sound a problem related to brown sender or the wiring of that sender?


What I've done so far, time period is beginning of this year up until this day:
-reflowed every solder joint on PCB, SI board and coding plug.
-carefully taken apart fuel, consumption and temp gauges. Resoldered thin wiring joints on each gauge. Checked for mechanical failure, but everything worked smoothly.
-two mounting studs on temp and fuel gauge removed and cleaned with sandpaper. These were quite oxidized. Not corroded, but darkened.
-checked continuity on c101 and blue connector behind cluster. Can't remember the exact pins now, but I had electrical manual nearby and voltage was ok during measurement.
-cleaned the brass nuts with sandpaper and they are tight
-changed SI board batteries, measures about 3,2 volts now
-yesterday I measured resistance values from SI board and compared them to an online chart. Every resistor had correct value within 5% limit.
-cleaned grounds between engine-chassis and battery-chassis. Also fitted thicker wiring, mainly for audio system. Stereo on/off has no effect on this problem.
Result from this procedure above is that fuel gauge now works perfectly. Speedo and rev counter have worked as should the whole time.

What has not been done yet:
-replace or check wiring for brown sender. This is a m40 car, so very tricky investigate without taking lots of stuff apart
-investigate fusebox/fuse 10 contact problem
-measure voltage after blue connector to the gauges on the board. There was continuity on the blue connector, even when consumption gauge was showing zero consumption and car was running but not moving. I have thought to take steering wheel off and then try voltage measurement with the boards exposed.

Any ideas on this quite little but very annoying problem?

Initial thoughts are the SI board playing up,but you seem to have covered that possibility!

Brown temp sender is not expensive,so may be worth a try....

my problem was brown temp sender

Thanks for replying. Just came from a short drive from local city central which I drive daily: consumption gauge worked ok when I drove there. Car was parked for few hours and when I started the car and drove back, consumption gauge did not move from far left position at all. One reason for this may be that before entering the city, there's a street which surface is very rough so lots of vibration. This situation has happened many times, but not every time. Maybe the vibration has an effect to some part of the cluster.

But I'll try new brown temp sender next and check its nearby wiring. Maybe after that a new SI board. Just thinking about the possibility that if the information goes through processors on SI board, could it be that internals of some processor are failing or working intermittantly for example due to the really rough road vibration.

try a new brown temp sensor first as malc has said mate, if it still does it take the clock out and see if the little brass nut is tight on the back of the temp gauge. there's a good chance that it may have worked loose..... very common thing on e30's