The oil light comes on intermittently on my car. I've learned to ignore it because I have enough oil pressure and there's no clattering of the valves when I drive. I believe this is a symptom of disintegrating wiring insulation and I need to change the lower engine wiring harness. I changed the upper engine wiring harness 15 years ago, so that is okay.

The problem is I don't know where the lower wiring harness is located. Can someone give me directions under the hood on where the lower engine wiring harness is located? I'd like to tackle this job when the car is down for the winter season.

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95 E320 Cabriolet, 159K

the few i've replaced also got to the nss on the trans. maybe 10 wires total. should be easy to follow, each engine and body is different, that's all i got. good luck, chuck.

It's called the "Battery" or "B" harness. It's for the battery and oil pressure sender. Easy to fix with a little new wire and soldering. Do a search for more info. Some hers >http://www.peachparts.com/shopforum/tech-help/271652-1994-e320-wiring-harness-eta.html

I'm still not seeing it. I was under the car and under the hood. The most I could see was a wire coming from the driver's side of the oil pan, and two coming from the alternator - one of them quite thick.

I tried searching, but all I get is information on engine wiring harness.

Well this might not be conventional method but purchase replacement harness and I'd bet you'll figure it out! Maybe?

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Dale

Before replacing the harness, are you sure it isn't just a bad oil level sensor? They are known to fail, the one in my SDL is that way, it randomly comes on and off despite a full pan. The wiring harness is fine (and not made of the dissolving insulation), but the sensor is all mucky. I've just been too lazy to change it. That light is easy to ignore.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Dale, I like your idea. Even just a picture of the harness would help me. I'll poke around for one.

Thanks for the tip on the oil level sensor. I may start with the wiring harness. At least that is money not wasted.

I gathered a lot of good wiring salvaged from scrap wheel speed sensors at work. I believe the insulation is silicone. I already used some to rebuild my throttle body.

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95 E320 Cabriolet, 159K

Does this look like the wiring?

Attached Thumbnails

 

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95 E320 Cabriolet, 159K

That looks more like a transmission harness.

The one you want will have the heavy positive battery cable, two .75mm˛ wires and one 2.5mm˛. The thinner wires go to the oil level sensor and the oil pressure sensor. The other goes to the starter solenoid. The other ends of the 3 smaller wires end up at a 3-way connector on the firewall near the master brake cylinder.

It's a fairly easy harness to rebuild however it is a tight space to work in.

Lookup 124 540 42 30 for a picture of your harness. This is for the sedan, I assume the cabriolet would be the same.

This is a How to on the the 500E board, search for lower wiring harness, sorry I could not link it. Part number is 124 540 42 30
I have a new one ready to go--do you still have your cab?

The part is relatively inexpensive and looks to be easier than the ignition harness.