'97 K3500 ABS issue - no braking power

K3500 and every year the ABS wheel speed sensor goes out ( and costs me a bundel). Then I'm left with near zero braking power in wet and definitely snowy roads. Any thoughts on fixing this more permanently or
even disabling the sensor or ABS unit? ( I would like to maintain the rear brakes with ABS if possible just not the front ).
Thanks!
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Which wheel speed sensor? A bad wheel speed sensor will not cause you to lose braking power, it will simply render the ABS inoperable. These sensors are somewhat notorious for getting dirty and going bad. Are you sure they are replacing it or just cleaning it. Usually they just need to be cleaned (some overzealous mechanics like to slop grease all over then while servicing other parts around it..)...I had to replace mine because it was cracked...your '97 ABS is a 3 channel unit I believe (front LT, front RT, and rear), so in theory losing a front wheel speed sensor shouldn't cause you to lose ABS in the rear. I thought the same thing on my '97, but that's not the case when my front left sensor craked due to low temperature, I lost all ABS. I don't know why the rear ABS didn't continue to function, and I don't think there is a cheap easy way of fooling it. The sensors on these systems have a pulse type signature that increases with vehicle speed, you would essentially need to replicate that..you'd need to hook up an oscilloscope and check the pulse as your driving, then build something to replicate it.. I think the 3 channel thing just means you'll maintain braking if one of the three channels fail with a pressure drop (leak)...
Ken
scott wrote:

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I believe there was a TSB on some of these? not sure but vaugely remember. Anyway, some other things to ponder: Sensor magnetic ring. Bad wheel bearing if its allways the same sensor. Heat can destroy the Hall-effect sensor. Cable scuffing. Bad connector, Check these Metripak connectors, they loose contact 'spring' over time.
Cheers

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Thanks for the insight. The dealer seems to replace the front driver side each time. What happens is the ABS becomes over sensitive and pulses the brakes to the point that I have like no braking power when it's wet or I hit a slight bump on the road ( like a pot hole or RR tracks ). I was hoping to just eliminate the sensor in the front. They state there are no sensors in the back or passenger side.
-scott
73blazer wrote:

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Same thing happened to my 99 1500. If your truck has the same ABS system as mine, then this should work. On the front hub where the plastic abs sensor plugs in to, will rust. The rust builds up between the housing and the sensor. This will push the sensor further away from the rotating grooved axel shaft. If it is pushed to far away, the sensor will not register movement. Now the system thinks it is in a full skid and will try to compensate. It is easy to pull the sensor and scrape the rust from the axel housing and you should not need a new sensor. This will require removing the caliper and rotor. You might try greasing the area on the housing where the sensor seats. This may slow the rusting process for next time. I do not think there are any long term fixes. Very poor design by GM. I almost killed a guy from this problem. Great safety feature!

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"73blazer" wrote

The system will not operate the rear antilock separately from the front unless everything is working properly. If you lose any of the sensors, or anything in the system is wrong so that you have the ABS light come on...the entire system is disabled.
3 channel just means that the 2 front wheels are modulated individually, but the rear wheels are modulated together. A 4 channel system would modulate all four wheels individually.
Ian
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