Cluster Electrical Gremlin

[apbt_rescue]

Recently picked up my first E30 and am working to solve various problems.

When vehicle is turned off and key removed the tachometer jumps up to about 1000 RPMs and seems to vibrate while the MPG gauge jumps to between 25-40 mark. Any suggestions or has anyone else run into this before? I don't think anything else is affected.

Should I be delving into the cluster or somewhere else?

Thanks

[bmwm42]

Probably bad si board its inside the cluster

[apbt_rescue]

I assumed the cluster would be coming out. Luckily the guy threw in the extra cluster he had when I purchased the vehicle so hopefully the other is in working condition or will have pieces available to swap.

Anyone run into this exact problem who could narrow down my list of potential causes?

[StereoInstaller1]

Probably bad si board its inside the cluster

Yeah, likely.