My wife has been bugging me to get after her speedometer failure in her 1990 745T. This car spent most of last year apart in the yard as it received a new engine. A good running 1993 940T engine and AW71 went into it without much fuss, but did take me about 4x as long as I envisioned.

Anyway, in the last month the speedometer went from "fine" to "occasional" to "All over the place" to "sittin' at Zero".

I suspected all of the issues were at the rear axle and my friends at the dealership agreed that's the place to start.

Got underneath today and found it's pretty hard to unplug the connector at the speed sensor in the rear axle- the panhard rod is in the way. Right, directly, perfectly in the way. So, with the rear wheels on ramps, I removed the bolt for the panhard rod to the axle (17mm + 1/2 in breaker bar). It came right off and pulled the rod down and out of the way.

Now I could see the connector, pretty well covered in grime and old undercoating. It plugs right into the top of the sensor on the back cover of the differential. I could immediately see the problem- one wire broken clean off, and the other missing insulation for about an inch.

I managed to squeeze the lock tab and wiggle out the plug. Tough to get out and tight for space there. Probably a lot more space on a lift, with the rear axle hanging. Also noticed the tab which used to hold this wiring harness has rusted completely off the axle. As well, the bracket for the e-brake cable has gone away... the pin, the triangle, the end of the bracket- all gone.

Well it was clear there was no real way to fix the connector. The copper was rotten and 1 wire broken right off in a connector pin. I cut back a few inches in the harness, found out the wiring is twisted (for noise reduction?) and noted which color wire went to which pin.

I am lucky enough to have a great parts car, a 94 940 NA wagon with a bad motor. A little looking under the hood yielded a similar plug along side the master cylinder. 2 pin female plug. I clipped it off, matched up the wires, spliced them to the 90's harness, and wrapped the new section with electrical tape.

I placed the new harness over the top of the e-brake cables to keep it from hanging down. I swung the panhard rod back into place, bolted it up, and went to work on the next project... while I was under there I realized she badly needed a front muffler, and the axle pipe end of the old muffler broke off in my hand. *Sigh* as a neighbor commented today, there's always something...

The test drive showed a perfectly working speedometer by the way.

--Rob Bareiss, New London, CT
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~ 92 244 M47 modified ~ 89 244GLT Turbo Conversion ~ 90 745T Auto ~ And a VW Bus~

Rob, is this connector identical to the 200's?

I never got a clean look at how it disconnects from the Diff cover. If this connector is the same on the 200's, Could you send me a PIC front and back so i understand how it locks in?
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/

The harness clips in to the sensor connector using a locking tab which, as Rob notes, is a little tough to reach. Jack up the rear end to do this easily. The harness is clipped to a bracket above the axle to keep it from fraying against the E-brake cable. I bought a new harness ($35 from Borton) and it took about thirty minutes to install it including fishing it from the trunk connector through the body hole.
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See the 700/900 "FAQ" at the menu bar top screen left side.

The reason I asked for PICS is that I have had the Diff cover off just to drain and replace the fluid.I had to take teh cover off.. After 100K miles of driving my car I found that the Dealer Stripped the Drain Plug during the car 500 mile fluid swap that Volvo did back then.
I took the cover off with connector still attached because at a glance I couldn't see how the heck it was attached. Very loaded with undercoating.
Every 100K I do the same thing. because I didn't want to mess up my connector just to change fluid.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/

Sorry, I didn't take any pics of the job. The connector tab on mine was also loaded with undercoating.

There's just one tab on it. It's squeeze-and-pull but it's an all-plastic type connector, not like the wire-spring connectors in the fuel injection system. If you've seen the one for brake fluid level, or the connector for the side marker lights, its just like those.

I was happy to find that my panhard rod bolt came out without a fuss. Crack it loose with breaker bar and it spun out easily by hand.
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--Rob Bareiss, New London CT ::: 1992 244 240K ::: 1990 745GL 289K ::: 1990 745T 266K ::: 1989 244GLT Custom 271K

The plug itself is the same as the one that's on top of the brake fluid reservoir of every 7/9 car I have seen. It's kinda a 'D' shape on its side. I clipped one off and tried it in a sensor off the diff, and it fits. I believe it will cure one of my issues also.

Yes, that's correct. 2-pin, female grey d-shaped plug.

They are used throughout the car, so if you need one to fix a speed sensor, another one from many other locations will work.

--Rob Bareiss, New London CT
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~ 92 244 M47 modified ~ 89 244GLT Turbo Conversion ~ 90 745T Auto ~ And a VW Bus~