Weird electrical problem

[75BMW2002]

My 91 318i has developed a weird electrical problem. When you first start the car everything works as it should and after about 5 seconds, all the gauges quit (every single one including tach, speedo, gas, etc) and the AC/heat fan will stop working as well.You can turn the car off a few seconds, restart it and it does the exact same thing.

Any clues?

Thanks

BOB

[DesktopDave]

That is an odd problem.  I'd check fuses 10 and 20, I think they're the ones that run the cluster & the blower fan respectively.  Does the problem happen when the blower is not on?  Maybe a short in the fan motor brushes?

I'd also check the unloader relay K7 as it drives both those circuits and is designed to lock them out when the starter is running.  I'd also listen for the under-voltage relay.  It'll make an annoying buzzing from somewhere inside the dash.  It's mounted above the steering column.

[75BMW2002]

That is an odd problem.  I'd check fuses 10 and 20, I think they're the ones that run the cluster & the blower fan respectively.  Does the problem happen when the blower is not on?  Maybe a short in the fan motor brushes?

I'd also check the unloader relay K7 as it drives both those circuits and is designed to lock them out when the starter is running.  I'd also listen for the under-voltage relay.  It'll make an annoying buzzing from somewhere inside the dash.  It's mounted above the steering column.

Checked K7 - replaced it with a good one and problem still exists (power morrors don't work either).  Fuses are good - everything works for 2 seconds then stops.  Doesn't matter if fan switch is on or not, guages still stop after 2 seconds.  Noticed Anti-Lock light and Battery light are on, but go off as soon as you rev enegine and stay off.  

Not sure where the under voltage relay is but you can hear something under the dash "hum" prior to starting each time.

I am totally confused.  Repalced igntiion electrical and this did nothing.