polecat702

Since I swapped out my non functional automatic, the speedometer has stopped working, and the ABS light is on now. About 2 years ago I bought all new ABS harnesses to each wheel.

I'm stumped, tried looking up on search function for the speedo, but no info. I may have not asked the question correctly.


HELP!

Mongo

I wonder how the sensors for the ABS look behind each of the wheels. Someone mentioned this to me in a very recent thread I posted this weekend. It couldn't hurt to check. As for the speedometer not functioning, could it be a broken wire going to the speed sensor at the transmission?

dr bob

Make sure the speedo impulse sender is still plugged in. Cable passes from the sender up into the spare-wheel area at the front of the well. The plugs need to be plugged in correctly, and ground post there is needed for the sender to work. My understanding of the later (91+) ABS is that the ABS unit generates the speedo pulse. The earlier car may need the external speedo signal to work. Get that fixed and I suspect the ABS problem will solve itself.

You can use a DMM testing for continuity to test the speedo switch/transducer. Connect the meter to the two wires, and you should be able to see the make/break/make/etc when you slowly rotate the rear wheels. the cable and the connections to the speedo impulse switch are sometimes damaged during transmission R&R, so another look there may tell you a lot.

polecat702

Will do, and thanks.

polecat702

Had it on the lift, fired it up and put it in drive. No ABS light, but still no speedo, after I changed the sensor on the differential.

BTW, I pulled every wheel sensor, and cleaned them all. I'm thinking that with the rear wheels turning and no ABS light, it's gotta be up front. Put it on the ground, ABS light came on as soon as I started moving.

Drove it about 60 miles last night, cars runs perfect, all the gages work, cept for the speedo, no cruise, most of the digital dash stuff doesn't work that's integrated with the speedometer.

This car is like a trophy wife, fun ride, but it ain't worth the hassles! Bought ready to set it on fire.

FWIW, the only wiring I touched was swapping the harness from my non functional transmission to the used one I bought. The used trans works great!

I'm at my wits end.

Any ideas would be appreciated, before I post a pictures of a car fire.

Hilton

The change to using an ABS sensor for wheel speed was later - '89 uses the reed sensor on the back of the diff housing to measure wheel rotations (and magnets on a disc attached to the differential inside the housing to trigger).

It connects in the spare wheel well - easy enough to unplug it there, put a multimeter on it, and check that the reed operates by holding a magnet against it (the reed switch is a small round puck, held on the rear of the diff housing by a short M6 screw and a bit of wire).

Hilton

One thing - its possible to install the reed sensor puck the wrong way around.. could try flipping it over?

polecat702

Hilton, I put the sensor in the way it came outta the broken trans. It always worked until the swap. I'll flip it just to be sure. Plus I had a spare, and swapped it too.

Hilton

What year did the replacement auto box come from? If its from a 90 or later, then it doesn't have the magnets inside the trans to activate the reed switch.

You can verify the year of the trans from the trans type and serial number stamped on the lower face of the ridge around the aft end of it.

polecat702

You're correct, I put it in upside down. Speedo is working fine now!

I feel like an idiot.