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Registered
1991 300D 2.5TD 320.000 km , 1991 300E 2.6 165.000 Km
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60 Posts
Discussion Starter #1
Hi Guys,

I'm having a problem with instrument gauges. Fuel, engine temperature, oil pressure, rpm indicator just stopped working. Odometer, digital temp indicator, clock, and all lights are still functional.

When I turn the car on I hear a buzz from behind the cluster, left side , where is the exterior light switch or the air vent.

When I use the turn signal indicator (right or left) the buzzing sound stops.

I removed the instrument cluster and replaced the rheostat ( thinking that may be the issue) but I continued to have the same problem.

Verified the fusees and those look all to be ok.

I would think this is a relay issue now!! Any idea or suggestion??

Thanks for your help.
 

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Registered
1991 300D 2.5TD 320.000 km , 1991 300E 2.6 165.000 Km
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60 Posts
Discussion Starter #2
Resolved: Fuse 5 was defective.

I don't know how I missed when I firs looked the fuses. Lesson learned :check twice before taking in parts other things and use a good light source!!
 

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Registered
89 300E; 00 E320
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2,515 Posts
I can't find a relay in the wiring diagrams. Look at fuse #9 again since it does not seem common to the things that are still working like fuses 5 and 6.

wiring diagrams:
Gauges 136 136-1 136-2 136-3 136-4 136-5 136-6 136-7 136-8

maybe a ground:
W1 Main ground (behind instrument cluster) Behind left side of instrument cluster 235-5

or a connector:

X26 Connector, interior/engine (12-pole) Lower part of fuse box 239-5

X27 Connector, starter harness Left side of component compartment, near brake booster 231-3

X18 Connector, interior/taillamp harness (8-pole) Lower part of fuse box 233-5

X4 Terminal block, terminal 30, fuse and relay box (2-pole) Top of driver’s footwwell, forward of parking brake lever 234-4

And then it could be one of the components in the wiring diagram like the fuel level sensor...Complicated schematic... Maybe someone can give a more direct possibility.
 

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Premium Member
About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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5,466 Posts
Common problem. I experienced it years ago with my 88 260E and I've written about it several times. Symptoms are always the same.
In my car's case the fuse wasn't blown; there was poor contact at one end.
 
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