Gauges not working

[street_127]

Okay, so I bought an 89 325i a couple of months ago and I have been trying to solve the gauge problem and have hit a dead end. The tachometer, fuel economy, and temperature gauge are not working. I just replaced the SI board with a re-manufactured one with brand new batteries. I checked fuses and they all were good. The previous owner had a shift light installed and I only have a few minutes to work on the car when I am home from college so I haven't got chance to make sure his wiring is disconnected. I have already tried hitting the dash and it didn't seem to work. Any suggestions?

[dnguyen1963]

Get the cluster out and examine it under a magnifying glass. Re-flow any cracked solder. Also, clean and re-tighten the ground nuts.

[jlevie]

A reman board usually has a jumper to isolate the battery until installation. Did your board have that and did you move the jumper to the operating position?

[street_127]

Okay, so the temp gauge definitely works. I let the car run for a while and the temp gauge was obviously working. As for the others... I pulled the cluster out and removed the tach gauge assembly. I took off and cleaned the ground nuts, and the solder is fine. I tried the board with the jumper in both positions and still no tach or fuel econ gauge.

[dashboardmonkey]

Does your radio and obc still work? They are on the same fuse. So, check fuses too

[Gregs///M]

Try looking at the cluster main board. This board is the junction between the car's connectors, gauges, and SI board. So if any of the solder traces or solder joints are cracked, there will be open connections.

You can reflow the solder on the main cluster board. That might fix it.

Casey, if all else fails. You can send me your cluster for testing or try it in another E30.

[street_127]

All the fuses are good. That is always my first step with electrical problems. Unfortunately I learned that from experience. I will check the main board next week when I am home. Thanks Greg

[street_127]

Decided to revisit the issue because I never go my tach working. Batteries are replaced. Fuses are good. Just put a new tach and eco gauge in my cluster and I still can't get it to work.

[jlevie]

Both the tachometer and econometer not working with a rebuilt SI board in place and with a different tachometer installed suggests that the tachometer and econometer signals aren't reaching the cluster. One cause of this could be a replacement engine harness from earlier than 9/87 on this car. The clue that might have happened would be the absence of C191. Another reason could be damage to those outputs from the DME (usually caused by an SI board failure).

[street_127]

I just found the issue. Splice 319 under the front left speaker. The green/red wire. Thank you for your help jlevie. Just have to put the car back together now.