Help with 1997 zj abs - JeepForum.com
 
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post #1 of 5 Old 09-25-2021, 08:03 AM Thread Starter
IdCrisis
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Help with 1997 zj abs

Hi i had problems about a year ago with my abs light comming on, did a scan and it was the module sitting under the pump controlling the pump, i fixed this by removing and opneing the box and resolder the 12 v connectors to the pump and all was good for ish a year,

here is my problem, about 3 weeks ago when it started to get colder i one morning ad the abs light turn on, drove to the store and when i was going to drive home the light was off (was around 15 min in the store) but after 200 meter i heard the abs pump start working and pumping without me touching the brakes, then i brake before a intersection and the pump worked the whole time removing brakepressure. then after driving for 5 min the abs deactivated and the light came back on. then after it continuing to pump the brakes randomly i disconnected the 12 v to the pump and have driven like that for ish 3 weeks, today i removed the abs pump controlmodule again and resoldered all connections visible on top but nope that didnt help abs light still is on.

what can the problem be? bad abs sensor?? and does a scan tool at a shop show witch sensor is bad?
i have checked the fuses both are good, so now ill have to wait till next month so i have the money to get the car computer scanned again. really hope that the abs module is not completly broken now ( they are 900 usd new ouch pluss shipping and import fees.),

so could symptoms of random abs engagement (both without braking and just light brake pressure) be symptoms of bad abs wheel sensor? or is it something much worse??

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post #2 of 5 Old 09-25-2021, 09:41 AM
HighLonesome
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When I had a broken wire in a rear sensor, the light came on after a few minutes of driving and the ABS was always working then, so I could hardly stop. I removed the fuse for the ABS and everything worked ok for a few years. I finally saw the problem was a broken sensor caused by a shop replacing the parking brakes. I replaced the sensor and it's all beautiful now. Braking is much better when the ABS is healthy vs. disabling it.

Sensors are 2-wire and can easily be checked for resistance. The rear sensors can be accessed near the amp under the rear seat. Front I don't know. I guess an intermittent (shorted or open) connection to a sensor could cause your kind of problem. Check the tone rings to make sure they are clear of debris. And I would check the sensors to see if they are resting in peace. One of mine was a little skewed and that's how I diagnosed my problem.
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post #3 of 5 Old 09-25-2021, 02:33 PM Thread Starter
IdCrisis
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Quote:
Originally Posted by HighLonesome View Post
When I had a broken wire in a rear sensor, the light came on after a few minutes of driving and the ABS was always working then, so I could hardly stop. I removed the fuse for the ABS and everything worked ok for a few years. I finally saw the problem was a broken sensor caused by a shop replacing the parking brakes. I replaced the sensor and it's all beautiful now. Braking is much better when the ABS is healthy vs. disabling it.

Sensors are 2-wire and can easily be checked for resistance. The rear sensors can be accessed near the amp under the rear seat. Front I don't know. I guess an intermittent (shorted or open) connection to a sensor could cause your kind of problem. Check the tone rings to make sure they are clear of debris. And I would check the sensors to see if they are resting in peace. One of mine was a little skewed and that's how I diagnosed my problem.
ok ill check the sensors yeah as u explained the pump is running even when not breaking but in my case not always, can the sensors just randomly go bad? cuz before the abs problem i had not done anything to the car in a while,

if a shop scans the obd2 port ( last time the scan showed that the contol module was the problem) will the scanner say whitch sensor might be bad? is that any codes that get stored?
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post #4 of 5 Old 09-25-2021, 04:25 PM
HighLonesome
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Sure sensors can go bad. There is soldering inside that could fail and a coil with enamel wire. The enamel can degrade and detract from the original properties of the coil. And each sensor has a harness.
I don't know OBD2 ZJs, only that the sensors are the same among all years. The sensor output is an AC signal, so I'll say the best check would be with an o-scope. A scanner can probably look at the signal some way too but not sure.
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post #5 of 5 Old 09-25-2021, 07:48 PM
PolkaPower
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On my 98 the wires were broken down in the corners to the engine bay near the firewall where they pass through.


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