The cruise, tachometer and oil pressure have all suddenly stopped working on my '89 300CE. I have removed the cluster and checked every connection and tested the fuse and made sure it was good. I then checked fuse #5 under the hood and it too was good. I read some old post on the diesel forums talking about OVP and cruise & tachometer. I couldn't get the relay to make any contact noise when I applied power to it. Also, when I shook it there is a rattling noise. Is this a sign of a defective relay? Does the OVP have any control on these items? The oil pressure gauge is pegged at zero whereas the tach does move upon startup but clearly isn't representing accurate engine RPM.

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1989 300CE

It is not connected, but if your OVP rattles I would replace it.

Sounds like the cluster is toast. If the tach is broken, no cruise, no A/C....

Double check the main plug that goes into the cluster on the left side (oil pressure side) hasn't broken or was put back on incorrectly. If it is not plugged in right, weird things will happen.

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There is a grounding bar connecting the three pods (instruments, speedo, tach/clock) together and then to ground (pin 1 on your connector). If the grounding bar connections have corrosion and thus no ground, these items will not work. You can take your cluster apart and clean the surfaces.

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1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
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http://www.fuelly.com/sig-us/40601.png

Yes, the main plug was my first thought and I double checked that it was secured. The A/C is working fine though. Does that mean my problem is somewhere else? I'm going to replace the OVP and clean grounds as per the post from Oldwolf above. The cluster was working fine before, it was only after the second removal that everything went haywire.

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1989 300CE

I changed the OVP to no effect but I forgot to check the cruise.

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1989 300CE

sometime back my oil pressure gauge when to zero ,the sender unit reading indicated normal oil pressure so i left it as is to replace on a free day. Surprising A few days later the gauge became re-operational ,and still is .a mystery.
mak

I'm going to clean the grounds up on the cluster and hope for the best. Cruise is still not working and I'm not really sure how it ties into this problem.

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1989 300CE

did you switch out fuse 5? sometimes they look good and they are not.

ask me how i know

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


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Yes, that was one of the first things I did and tested it for continuity.

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1989 300CE

I had related issues and could not find the break in the ground circuit. I finally resorted to running a ground wire from one of the metal screws off the back of the clock to a ground behind the cluster. The gauges all popped back to life with no issues.

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1989 300E

2005 Acura TL

2011 Hyundai Elantra Limited

Swing hard! Take chances!

Well I cleaned all the grounds but there was no effect. I then decided to add a ground and to my amazement the tachometer and oil pressure gauge came back to life. Unfortunately, as soon as I turned the turn signals or either the park or headlights on, both of the gauges went dead but would come back to life as soon as I turned them off. Where can I add a suitable ground that won't be affected by what is obviously the instrument lighting?

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1989 300CE

Anyone?

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1989 300CE

check the fuse

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1990 190E 3.0L

Already done as indicated in previous post above.

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1989 300CE

maybe the fuse connector then? it seems like everything you are describing somehow ties in to a piece linking all the malfunctioning parts. wouldn't a wire of some sort cause your fuse to blow? You said the fuse is still intact so it must be something else. when my tach, oil pressure, temp, and turn signals died it was because of an issue in the fuse box. I'm not disregarding what you have already said you did, just trying to throw out a simpler suggestion before you go into any extensive and unnecessary fixes.

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1990 190E 3.0L