-94 Trans Sport ABS problem

My car's ABS-light has been going on and off for a while now. today I spent hours cheking all connectors and sensors on both front wheels. I have a cable+software to check tdc:s, but I'm not sure if it works correctly. It has a few codes stored, mainly pointing to left front wheel sensor. I did all checks mentioned in factory manual, but could not find any broken wires, connectors or sensors. When I start the engine, ABS light stays off, but as soon as I put gear on, light lits and stays on until I switch off the engine. I discovered that if I start the engine, and put gear to neutral, light stays off, but if I then rotate left front wheel with my hand (front of the car of course off the groud :wink: ) ABS light lights right away. If I try this on right side, light stays off. I tried to shake left front wheel to check if bearing was bad, but to my experience it was OK. I don't want to change front wheel bearing, unless I'm sure it has to be done. New bearing costs here 400 Euros (480 $) :frown: If I could wait I'd order one from Canada (have relatives there) but I have to take my car to yearly inspection by the end of this month, and ABS must work then.
Any ideas anyone?

I did not have such a specific problem but found my ABS light came on intermittently until I replaced the alternator. It's been okay for quite a while now.

This morning I decided to pull left front bearing out and check ABS sensor. This is what I found:
http://koti.phnet.fi/vesamaan/transsport/IMG_2506%20(Medium).JPG
More pictures here (http://koti.phnet.fi/vesamaan/transsport/)

I need the car every day, so I decided to clean all the rust and water, and put everything back together. Bearing itself was still in good condition. Put a lot of grease everywhere to keep water and dirt away for a few days, until I have time to go to the yearly inspection :) . ABS works fine now, light stays off and everything looks good. I'm pretty sure it is possible to repair this sensor, eventhough GM manual says it can not be done. If sensor (coil?) itself is OK, just clean everythig, put new grease in and put it back together. If you want to do this properly, you must find new gasket to inside of the hub.

I'm ordering new bearing from Canada, but it will take few weeks until my relatives fly here and I get new part.

..I decided to clean all the rust and water, and put everything back together...

Is it possible to open the bearing unit and then put it together, without ruin it? I thought the unit were damaged when opened?

Is it possible to open the bearing unit and then put it together, without ruin it? I thought the unit were damaged when opened?
I thought so also but I did it and have driven 100 km after doing it. No problems so far... I'm happy if ABS works for 2-3 days, I'm going to change new bearing as soon as I can get a new one for reasonable price.
I didn't separate bearing and toothed ring from each other, just took whole bearing+ring from the hub.

In the picture in my second post, you can see ball bearing in lower right corner of picture. When openig the unit, bearing stays with its frame (?) which connects to knucle with three bolts. so when you open the unit, you don't actually take bearing apart.

I thought so also but I did it and have driven 100 km after doing it. No problems so far... I'm happy if ABS works for 2-3 days, I'm going to change new bearing as soon as I can get a new one for reasonable price.
I didn't separate bearing and toothed ring from each other, just took whole bearing+ring from the hub.

In the picture in my second post, you can see ball bearing in lower right corner of picture. When openig the unit, bearing stays with its frame (?) which connects to knucle with three bolts. so when you open the unit, you don't actually take bearing apart.

I have been looking in the factory service manual, and according to the manual, the ABS sensor is possible to remove from the bearing unit when the unit is loose from the car, but the sensor is damage and have to be replaced!

It is clear from your pictures that the inner seal is the weak point. Does anyone know if it is possible to order just the seal from GM? It looks like a very good idea to replace the seal preventive before it gets bad, to save the more expensive ABS sensor and bearing unit. The seal can be replaced at the same time the outer CV joint boot is replaced.

Antti, can you take some picture of the new seal, and also take the dimensions of it, before you exchange it? I can then buy the seal from a independent seal supplier.

Regards Niklas

I am having the same problem with my 93. I can start the car, back out of the driveway, and after 3-5 seconds of about 10 Kph the ABS comes on. So the ABS passes the initial check at start up and only dies after moving forward. Is all this related to the wheel bearing. How do the two problems connect? Is the sensor in the bearing?

Hummm.

I am having the same problem with my 93. I can start the car, back out of the driveway, and after 3-5 seconds of about 10 Kph the ABS comes on. So the ABS passes the initial check at start up and only dies after moving forward. Is all this related to the wheel bearing. How do the two problems connect? Is the sensor in the bearing?

Hummm.
My problems was like that in the beginning, and in couple of week it was like i described in first post. Have you had this problem for a long time?
The sensor is in the wheel hub assembly, which includes bearing http://koti.phnet.fi/vesamaan/transsport/IMG_2509%20(Medium).JPG
In this picture you cn see wheel and a toothed ring. The ring is part of the sensor, other part is somewhere inside red circle in this picture, covered with grease and dirt
http://koti.phnet.fi/vesamaan/transsport/IMG_2511%20(Medium).JPG

I've only had this one for about two months, and it was like that when I bought it. If this is the same problem, do I only need to change the bearing or the sensor, or both?