No more speedo signal from new diff

[rammstein]

I changed out my differential. I used the old cover and old sensor. Got car all put together, drove it, and I got no speed. No biggie, I figured- I probably didn't push it in right, or maybe the connection was dirty. Nope- no workie. At abotu that time, my alternator stopped working. I had the alternator replaced at the local shop last year, so I brought it back and they warrantied it, so that's cool. I was also sick of the car, having spent 2 weekends working on it, so I asked them to put a new speedo sensor on there, and they did. Still no worky. They even hooked up another cluster just to test that, and the other cluster also did not show speedo signal.. They just called and said they give up, so I pick up the car tonight.

What the hell do I do now?

[jlevie]

Did the new differential come from an E30?

[rammstein]

Negative- it came from an old 5 series.

[Lof8]

hmm, I'm close to installing an old 5 series diff. Whats the trick here?

[328ijunkie]

I have some ideas on the matter. Ill go back and look through my pictures of the diff build.

[rammstein]

Nice- thanks Dave. This one is a head scratcher.

[Mikhail Bakunin]

would like to know. Does the wheel and sensor not line up?

[rammstein]

It certainly LOOKED lined up, but maybe the fins aren't going in far enough?? Now I am reluctant to open it, because I'd have to redo the gasket and waste $40 in gear oil.

[Mikhail Bakunin]

Maybe the 20 year old wiring or connector got messed...just a thought.

[rammstein]

And a good thought, although I would like to think I was gentle enough with the wiring to avoid breaking it somwhere. I have a few plans to test that the wire is still good- some involve a multimeter, others involve spinning the old diff with the sensor held up to it to see if the speedo reads. I WILL figure this out. The car is way too close to perfect to stop now. Plus I will undoubtedly get a ton of speeding tickets otherwise.

[redhatpat]

Get a continuity tester and hook up the leads to the two output poles on the speed sensor. Then jack up the rear and spin the tires. You should get a beep every time a pole passes between the sensor. If not, then you know the sensor isn't sending out a signal.

I had a similar problem, and it turned out to be the wires coming from the sensor plug, they're pretty fragile. You might have been broken them when you swapped out the diff.

[jlevie]

My suspicion is that the diff has a different sector ring in it. In which case you'll need the speed sensor used on the car the diff came out of.

[rammstein]

My suspicion is that the diff has a different sector ring in it. In which case you'll need the speed sensor used on the car the diff came out of.

By sector ring, do you mean the wheel of metal tabs that runs through the sensor? If so, if I DO end up having to pull the cover off (god help me if I do, that will suck) I will take a picture of the old and new ones side by side open.

Man, this friggen sucks. I thought I was gonna bolt this up and be done. I wonder if I can just find a matching cover at a junkyard. Hey Dave- can you confirm what model this came out of? It would be pretty ideal if I could just find a matching cover at the junkyard and get this overwith.

[328ijunkie]

This is an interesting issue. Based on the pictures i have of your diff when i built it (which dont show that ring very well) and all the other pics and diffs i have laying around, theres not anything different (that i can tell) between the pickup rings... And sadly the original cover that came with that diff wont work as it has a different mounting pattern from the E30. The speed sensor may work however. I still have the cover and sensor (i think) and will see if i can notice anything different with it. ill be out at the shop in a few hours hopefully with an idea for you.

And yeah sorry again for the issues, this is the first time ive seen this issue and have run this exact diff in another car without issues.... hrm.

[rammstein]

Thanks, let me know. I'm hoping I can get time to do a few tests on the sensor. Worst case I don't get to test stuff until the weekend- it all depends on how late I work every night.