W124 ambient temp sensor removal
 

The ambient temperature display in my 300D isn't working, and I think I've narrowed it down to the sensor. I have a replacement thermistor, and looking at the CD manual it should be simple to get at the old one, clip the wires, and solder on the new one.

But what I see when I take off the license plate is different from the picture on the CD. There's a round grommet behind the plate that is supposed to cover up the thermistor. The picture makes it look like the wires come out from the lower edge of the bumper, then run sideways for a couple of inches to the grommet. But on my car there are no visible wires, and behind the grommet is what appears to be a block of styrofoam or something similar.

Is this normal?
If it's not normal, was my car perhaps front-ended and repaired badly?
Should I take off the bumper to see what's going on? Any tips for removing the front bumper, or getting access to the space directly behind it some other way?

Thanks!

Alex,

If you have an early 87 300D, the outside temperature sensor is a small chrome tip located on left side of the front bumper, underneath the impact strip.

Thanks for the quick reply Speedy. By "left side", do you mean the driver's or passenger's side? What's the best way to get at it---is it accessible from below, or maybe by taking out one of the headlights?

It would be on the drivers side protruding about 1/4 out a hole under the black bumper guard. BB

Found it! Thanks guys!

I still don't see how to get to the wiring, though... should I take off the bumper, or the splash shield inside the front of the driver's side fender, or both?

Man I hate it when the FSM doesn't tell you about these intra-year changes. :mad:

Alex,

I haven't got around to replacing my sensor yet. The wiring for the new sensor is quite long, so I plan to keep the old sensor in the side of the bumper, and wire in the new one behind the front license plate. I think the procedure for installing the sensor is in the service CD's. It is routed behind the bumper (bumper removal is not necessary) and driver's side headlight, and up along the top of the wheel well into the fusebox.