I am working on a buddies 82 300d and for some reason at random the tach will go crazy along with the seat belt light and glow light flickering, or coming on real dim. It usually does it for a minute or so then goes away and then comes back. It almost always does when you first drop it in drive. I cant seem to get it to do it sitting still in park. Now i know the tach amp can cause problems with the tach, but this isn't just the tach. I've also swapped the seat belt relay with no luck and unplugged the connector from the seat belt itself. Any ideas? This one has got me stumped. Forgot to mention, i did check the grounds behind the cluster and the cluster itself. All looks good. Thanks in advance.

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Over voltage protection relay? Check the small blade fuse on the OVP located in the fuse box.

Does the AC act up as well?

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----Adam

1985 300SD 322,000

Forgive me but where is the OVP? I must be overlooking it. What do you mean by AC acting up? AC is working minus a couple of elements that i have bypassed.

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an 82 300D will not have an OVP, so don't try looking for it. My guess is bad ground connections in the instrument cluster itself. take it apart, and remove the screws. likely you will find the plastic the screws thread into has shattered, and the screws are very loose, and when they get loose, the cluster looses it's ground!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I did check for this as i had that problem with my old 240d a while back.

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