ABS Light Coming on Randomly

[Uncle1957]

HI:

My ABS light comes on and stays on if I brake hard. Yet when I stop and restart van it goes off.

Today it came on when I started the van. Granted there had been 8 inches of snow on the van. Foregn material here. Normally our temp in winter is 40 - 50 degrees. Once engine warmed up I stopped and restarted van ABS light went out.

Is this normal if not any ideas??


Gord

[llerrad]

No not normal, could be water in the sensor connection at one of the wheel brg's or failing sensor and water getting into the brg./sensor area. I've had this before and it was only a matter of time when the ABS light would not turn off unitil the bad sensor was located and replaced.

[kcarlen]

You can get it tested at a garage that has a tester, or you can buy one. It will tell you the exact sensor that is failing, or where the short or open signal is occurring. The problem is right now is that you don't know which wheel, or module is causing the problem.
You could just climb underneath, and inspect the 4 -2 wire circuits and connectors for injuries....

[Uncle1957]

That makes alot of sense. Whenever the issue happens it has been raining or huge amount of moisture in the air. So am I correct in assuming that a starting poin would be to check the electrical connection to the wheel berring area. Possibly spray with contact cleaner. How expensive are the testers?

Sounds like it could be expensive....

Thanks

Gord

Originally Posted by kcarlen

You can get it tested at a garage that has a tester, or you can buy one. It will tell you the exact sensor that is failing, or where the short or open signal is occurring. The problem is right now is that you don't know which wheel, or module is causing the problem.
You could just climb underneath, and inspect the 4 -2 wire circuits and connectors for injuries....

[Michelg777]

I have a 2001 Montana 66K miles. My ABS light has been comming on about 2 minutes after the car is started. I checked the connections and lead wire at the front wheels, no issue. I cannot find the connections at the rear wheels. My OBDII is not giving me a code. I wish I could tell what wheel is the problem without taking it to a Dealer. Replacing a hub bearing is not difficult. Does any one know where the rear wheel connections and how to detect the wheel with the bad sensor.

[brian 1]

the rear connectors are just below the rear brake line at the middle of the backing plate behind the drum.you will see a connector.you can dissconnect it and take an ohms reading at the sensor with a fluke meter.it should be between 850-1350 ohms.if you have a code reader you can monitor wheel speed sensor data.it will tell you which one is dropping out.

[Michelg777]

Brian: Thank you for the connector information. Before I give the ohm meter a try. I would like to try to properly use my OBDII scanner to detect the suspect wheel sensor. My scanner is not giving me a wheel sensor code. My scanner has live data, but I dont see a section in there for ABS data. Do you have any suggestions.

[brian 1]

only suggestion i can give is you need to have an abs scanner that can read wheel speed sensor data.sorry but no other way to check,but to take ohms reading on every sensor or get a scan tool that can read abs problems.sorry but this is only advice i can give.

[Michelg777]

I took the measurements at each connector:

LR - 1.4 K
RR - 1.3 K

LF - 1.6 K
RF - 1.4 K

After taking the reading I moved the wheel while the meter was still cnnected. The numbers jumped around. I guess thats a good sign all is well.

I cleaned all the connections with electrical spray and then sprayed a little WD-40 in each socket before making the connection.

Of all the connections the left rear was wet and dirty. That may be where the trouble was.

I took the van for a 3 mile test drive and the ABS light did not come on. That does not mean I fixed the problem. If I can go a few days then I thinks I fixed it.

I will keep you posted.

Thanks for all the help. This is a great Forum. Mike G.
opcorn:

[kcarlen]

Uncle1957, I am curious to know if you have solved the problem.
I just replaced 2 of my front hubs in the last month and that is when mine started doing the exact same thing. (ONLY ON WET/HMID DAYS) this leads me to beleive that there is a short or "exposed" connection somewhere.

It may be just a coincidence, or maybe one of the new bearing sensors are bad.
BTW, I purchased them off ebay, hold off on buying them until I figure out what is going on with this supplier...I don't know if I would recommend him at this point...I will keep you posted..(Wheel bearing hub and sensors complete)

If it is a DRY cold day, the ABS light will stay off. I have checked the connectors, and they appear as good as they were when I replaced the new ones. I have not even thought about the back.

BTW, your ABS system is not read by the OBDII control system.
You need a seperate reader for the ABS. The ABS controller is not made by the DELPHI group, thus a seperate software system reader is required...

Same goes for your airbags if you ever get to that. ( I used to develop software control systems for Delphi in 2000-2004).

[kcarlen]

UNCLE1957?

Is it fixed?

[Uncle1957]

Have not had a chance to crawl under the van and check the connections.

Hope to do that this weekend,

Gord

Originally Posted by kcarlen

UNCLE1957?

Is it fixed?

[kcarlen]

I was under mine this weekend, replacing another bearing/hub assembly, and found a bare exposed speed sensor wire...rubbing the hub.

Replaced it, and it is as good as new.

It is really important to keep the strain on the wires facing down, away from the hub. If you don't use the intended clip area, then you will eventually be replacing the hub for the same reason I did.....

Good luck..

[Uncle1957]

I got around to checking my front ones both have resistance of 1400 ohms.. Drivers wheel connection was not good. Rear ones the wire goes into a hole in the axle. Do you need to remove the drum and everything to access it?


Thanks

Gord

Originally Posted by brian 1

the rear connectors are just below the rear brake line at the middle of the backing plate behind the drum.you will see a connector.you can dissconnect it and take an ohms reading at the sensor with a fluke meter.it should be between 850-1350 ohms.if you have a code reader you can monitor wheel speed sensor data.it will tell you which one is dropping out.

[rockwood84]

low brake fluid level will sometimes make it come on too