Intermittent Rear ABS light

I have a 97 Rodeo automatic, 4WD in which the Rear ABS Light and the Brake light will come on intermittently. They will stay off for days, then pop on again usually at speeds greater than 35 mph. Doesn't come on during braking manuevers. Might stay on for several days and then go off while stopped at a traffic light.
My local Isuzu dealer tried to pinpoint the problem twice. No codes appeared, even when the light was on. They didn't charge me any $ to diagnose, and removed and cleaned the speed sensor on the rear axle.
A tech even drove my car for a day and a half to try to get a code while moving. They essentially came up without a cause. But they suggested an expensive list of parts replacements that would be done until the problem went away. I declined their offer. ($80 per hour!) My own limited research suggests that ABS problems are normal on Rodeo's. But none of the info describes my problem. I live in a high road salt winter region. Something may be corroded. I've spent some time poking around but don't want to ruin anything that is still a good part. This is the only problem I have with my Rodeo - it's been good to me.
Any suggestions? Is there a likely area to focus on? Hopefully one of you have been there and done that. Thanks for your interest in helping!

Hello. The rear abs speed sensor is notorious for going out. It is about $70 from your Isuzu dealer(100 from honda) . You might be able to get one from a GM dealer for even less. Lots of these parts are GM. The one my friend got from Isuzu for his Passport came in an AC/Delco box with an AC/Delco part #. I don't have the part# in front of me, but take away the first letter of the Isuzu part # and you've got it. I just took out the ABS fuse on my Rodeo because I don't like the way the rear ABS works anyway. Good luck!

I changed out the speed sensor twice on my 95 Rodeo. Light would come on, and stayed on after a few minutes of driving. Brake would not behave normally because wrong speed was being detected and wrong signal being sent back to the computer which controlled the ABS. I don't think you can actively clean out the speed sensor, but you can measure it using an ohm meter to see if it is still good or not. I forgot what the reading is though. Do a search in this forum, you will find it. Cost for speed sensor is around $80.00 at Isuzu (cost more at Honda). You can ask someone with a repair shop get it for you and you probably will save some $$.

Here is a thread on the ABS light:

http://www.automotiveforums.com/vbulletin/showthread.php?t=236839

Dale

Thanks to all of you with suggestions, and the link to the previous related issue. I have good brakes all the way around. I guess the speed sensor is the way to go. Looks easy to replace - I'll do it myself. I can at least rule it out, as I have a crappy cheap analog ohm meter that won't be much help to confirm the right circuit value. Winter's coming, and ice too in a couple of months - don't want to wonder about the antilocks anymore.
Thanks again.
Highland

Welcome to the ABS sensor failure club. I too have a 97, and it's gone through 3 sensors, the 4th just went a few weeks back.

Cure - electric tape to hide that idiot light; I will not replace it again.

Truck's been real good to me too; this has been my only complaint about every other year.

I think I'm the one that causes it, however.

Thanks for the membership sympathy. I'll pursue the possibility of getting the part thru GM as it might be a few bucks cheaper. And then maybe buy an extended warranty for the sensor! wouldn't that be nice. i appreciate the response. Highland

Ok, I gave it a try......I replaced the ABS speed sensor (located on the rear differential) and only gained a little ground.
The rear ABS light had been on almost continuously for the last few weeks. It would go off at times too. After installing the sensor (wiring harness looked good - no damage) which cost $91.00 with tax, the ABS light went out and stayed out for three days. But now it's coming on again for a few seconds while moving at a constant highway speed. So the problem is still there, only less so than before. Any suggestions?