I have a sensor wire hanging ? - PeachParts Mercedes-Benz Forum

johnson · #1 10-26-2006, 04:34 PM

My 1990 300e suddenly started running rough and missing.

I replaced the plugs etc but no help.

I started looking around and there is a wire with a rubber plug hanging down next to the starter which has a single connector in the center, It must have just come loose because the contact inside the plug is clean and bright.

The wire originates at the back of the valve cover on the driver side and comes out of the harness running along the intake going to the ECM behind the battery. what might this be and where do I need to look for a socket to plug it back into?

Any help will be greatly appreciated

johnson · #2 10-27-2006, 01:33 PM

Hello, is this thing on?

TMAllison · #3 10-27-2006, 01:51 PM

It's on and working well.....there are a lot of wires and plugs under the hood, it's difficult to know which one you are talking about from a verbal description alone....try posting a photo of the plug and the general area it came from and quite likely another owner of your model or one of the techs on the board will recognise what it is and respond to your post.

Good luck.

Gilly · #4 10-27-2006, 04:22 PM

How many wires for the connector, 1, 2, 4? Colors? I assume 1 wire, not sure. Yes a pic would help. I was thinking O2S connector, but on a 124 that's under the passengers sside carpet.
Dan

johnson · #5 10-27-2006, 10:43 PM

Here's a picture. It's a single conductor/black

Gilly · #6 10-28-2006, 06:24 AM

I'd try tracing it. It does not appear to be original, like from something that was added to the car and later removed? MB is not really known for using that corrugated type wire sheathing you can see at the top of the picture.
Gilly

OzC36 · #7 10-28-2006, 08:23 AM

Just a shot in the dark, but do you think it is:

Transmission case, vacuum box, solenoid valve, control pressure cable - part no. A 124 300 51 30 or A 124 300 58 30?

Gilly · #8 10-28-2006, 10:54 AM

The only thing I can think of, and not really even sure what it's called because I've never had to mess with it, is something towards the back of the transmission, kind of behind the oil pan, maybe on the tailshaft housing? It would be visible from on the ground under the car. It may reach that if you brought the wire around to the other side of the transmission, passengers side. May have used that corrugated conduit like that too now that I think of it, but there isn't much else on the car that would use that type. It would be in a pretty exposed area under the car (along side the tranny pan) which might explain why they used it....
Gilly

Gilly · #9 10-28-2006, 11:01 AM

Component I'm thinking of is Y3, Transmission Kickdown Solenoid, right rear corner of transmission, wire would lead to the MAS relay, which is in the area you are talking about, the bright metal box with that weird "wing nut"-looking black knob on top of it.
Gilly

johnson · #10 10-28-2006, 01:59 PM

I'll check out the sugestions.

It comes out of the wiring harness at the back of the plastic trough that runs down the valve cover. It doesn't look like a later addon sense it's intergrated into the harness. the wire does head in the direction of the MAS relay.

Thanks for the replys

johnson · #11 10-28-2006, 03:48 PM

The wire to the Transmission Kickdown Solenoid is there.
This wire is not long enough to go that far back.

Would it be something to do with the cruse? Or the air metering system. The metal on the inside of the plug is very shiny so I don't think it's been unpluged that long.

Gilly · #12 10-28-2006, 07:51 PM

Nope, can't think of a thing that it would have to do with for the cruise. Cruise gets speed sig from the speedo in the car. Other than that there is a large 6 pin connector for the cruise servo. Air metering? That the plate you see in the center of the "air horn" when the air cleaner is removed, nothing to do with that either. I was thinking that wire might reach the kickdown solenoid if you brought it over to the right side of the transmission (up over the top and let it dangle on the other side, then back).
If everything working OK? Do you HAVE a cruise problem or suspect problem with the air metering system??
Gilly

johnson · #13 10-28-2006, 08:40 PM

The car suddenly started running rough, I spotted the plug dangling when I was under the car looking for the O2 sensor.