[GeorgeV]

Since I purchased this otherwise perfect condition 1989 300TE, the oil pressure gauge goes to full as soon as the ignition is turned on and remains there until the ignition is turned off.

I've changed both the oil pressure sender and the oil pressure gauge itself and also checked the wire to the instrument cluster for continuity. Problem: the color of the wire at the instrument cluster is not the same as the color departing the sender and no continuity is detected.

Any ideas? Is the wire supposed to run straight from the sender to the gauge cluster or does it go through a junction? Thanks for all help.

 

[augapfel]

Oooo, an electrical mystery! My favorite.

Wire color at the sender should be brown with a green tracer. The wire passes through a 3-terminal inline connector (X27) location unknown and then goes directly to the cluster. Color does not change. The wire at the cluster is held by a small connector, not the big round one. 4 cavities, I think. 3 used. The brown/green wire should be in cavity 4. Cavity 1 should be brown/blue and cavity 2 should be gray/blue. Sounds like some wires got move around on your car. Good luck.

Define perfect? What colors, miles, etc.?

 

[GeorgeV]

You sir are a wiz.

Indeed the wire at the cluster is Brown with a Green tracer but.... the wire at the sender is "Black" which lead me to think that the portion between the sender and the connector may have been replaced at some time.
As I said, no continuity between these two. If I could find the 3-terminal inline connector (X27) I would run a new wire to it, where is it hiding?
As for the car it is dark grey with grey MBtex, 60.000 one owner miles, garaged and as new inside and out. I also have a 1988 260E in good shape but the TE puts a smile on my face every time I drive it. I can not garage it (full of unused sports cars) and my only fear is that at some point I will have to paint it.

Thanks for your help. Maybe you'll remember where to look for X27.

 

[augapfel]

The other wires passing through X27 are ppl/white (goes tothe starter motor) and brown/black (goes to the low oil level switch). Shouldn't be too hard to find X27 with that info. Have fun.

 

[GeorgeV]

You are quite right. With two more wires to follow I should be able to find X27.
I shall report.

 

[augapfel]

It's gotta be at the left rear of the engine compartment. Could even be on the top of the engine at the rear. Those three components are all in the same general area.