Tach sluggish when cold

[Gelatinous]

Hi all, I figured I should create a new topic for my non charging related problem.

After my car (83 528e) has sat over night the tach is very very sluggish as in like 5 minutes to reach idle RPM. This symptom goes away once the cabin is warm. Are there any special places that need lubrication in the tach?

Thanks

[Gelatinous]

damn, I was hoping someone might've had an idea about this. Currently it is cold enough that during my 60+ minute commute the tach might make it up to 1000 rpm.

[RonW]

That sounds like a problem with the instrument cluster circuit board. Your '83 has the old style circuit board, which I'm not familiar with, but circuit board problems are common regardless of the model year.

I've never heard of a problem with the gauge itself, so to answer your question, I know of no lubrication points for the tachometer.

[Brad D.]

Agreed, it does sound more like an electronics issue.

[Gelatinous]

got a cluster from an 86 535i and swapped speedo and tach. my tach now works much better! So I'm going to try to diagnose my tach at work.. pull and test some components.

The 'code' plug for this tach is little more than a piece of plastic that lifts two pins in the connector on the bottom of the tach... operation is not affected with this in or out... any idea what it is for?

I did however notice that the speedo from the 535i has the O2 plug blocked off... as in there's factory plastic covering the connection point and no removable fuses on the back (my old one has two). I also noticed that the active check control in the donor car didn't have an O2 light.....

I'm wondering if anyone has seen this at all?

Thanks!