New 535i Owner needs help

[NWDriver]

Fist what a great car, second what a great form. Now for my issue.
I just bought my first BMW. Am very happy with the 1990 535i. When I bought it the previous owner told me of a an issue with the Tach and Spedo cutting out every so often. And seems to happen more in the cold and rain. Well I have owned the care for 3 weeks put 2k miles on it and loved ever minute of it up intill last weekend when it started to rain and get cold and the Tach and Speedo failed to stop working. Everything elese on the guage cluster works fine except for the speedo and RPM gauges. The RPM said I was idling at about 300rpm, while the speedo never rose above 10 once I started driving. When they moved, they did so very sluggishly. Eventually, while on the freeway at somewhere around 70, the RPM needle showes 1000rpm and the speedo registered 20mph. In what diagnosing I have done so far the I belive that the speed sensor is ok, as the OC still gives me accurate Avg MPH and the Cruise Controll functions with out any problems. Car runs smooth, has power, no signs of mechanicle problems.
The previous owner belived that this problem was related to the Crank Shaft Speed Sensor (Not the Pulse Sensor) needing to be cleaned or replaced. Could this be it?
Or am I looking at a new Gauage Cluster?
Any and all coments, opinions and ideas would be greatly appreciated.

Thank you all
Fred
Still loving the 5 series wondering why it took me so long to own one.

[gale]

I had the same symptoms with mine a few years ago, just like you say, more likely when cold & damp. I replaced the battery even tho it "passed" a load test, started parking the car in the garage, and never had the problem again.

Could also be the instrument cluster, do a search for "capacitor fix" or visit Bruno's site.

[NWDriver]

Thanks for the feedback. I got a new battery and it started stonger. As soon as it was cold and wet out problem showed its self again. Sorry to say I can not garage it.
So before I dive into the Guage Cluster or get a new one. Could it be the Crank Shaft Speed Sensor (Not the Pulse Sensor). Looking for feedback as I know it is all part of the electical system but I would think that the fault syptoms would be different.

My confusion with the compasitors is that one would think that when the car warms up inside from heater that it would self correct. I am truly confused with that theroy?

Any and all coments, opinions and ideas would be greatly appreciated

Thank you
NWDriver
(aka Fred)

[Kalevera]

They could be unrelated problems, but I would suspect an electrical fault in the dash module. Also, I believe the capacitors are irrelevant to the speedo and the tach (they just do temp/fuel). Before you pull the dash cluster, though, I'd check the diff speed sensor, which may help your speedo issue, but won't affect the tach.

I know very little about the crank speed sensor, beyond where it is located on the car. However, if it were misbehaving, I believe you'd have a check engine code. Have you done a stomp test?

best, whit

[Javier]

no I do not believe it is CPS related.

Check all the fuses related to the cluster (F1, F17 and F20). We are no looking for blown ones, but dirty or corroded spades.

If all are OK, go behind the cluster looking for loose or weak connections, use the opportunity to replace all electrolytic capacitors, and clean and condition every connecting plugs.

Tach gets its signal from the DME (ECU) control, DME condition the CPS signal. Spedo gets its signal from the differential installed speed pulse generator, cluster conditions the signal and send it to the gauge, so it is hard to believe it is a source signal issue.

Javier