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Charlymich
User

Aug 8, 2018, 7:03 PM

Post #1 of 9 (287 views)
  post locked   Abs  

Brand new member looking for help diagnosing ABS on 2001 Chrysler lhs 3.5. ABS and traction control comes on. resets after igniton cycle, then on dry pavement at random time and speeds Abs motor starts for a couple seconds then throws the ABS and traction control lights. There are no ABS codes with Actron or Auto enginuity. I monitored wheelspeed sensors and found that RF sensor cut s out signicantly sooner than the rest. Replaced sensor and sensor is now very responsive. Monitered wheel speed again and while applying brakes to a gradual stop, lost input from new RF sensor at the same instant Abs motor turned on. I get the impression that the Abs unit is causing lost signal from sensor. Don't know whats causing pump to activate. One would think that signal loss from sensor would cause this, but sensor responds beautifully except when braking SOMETIMES. Tone wheel is clean and in good condition and all suspension is tight. Any ideas?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 8, 2018, 7:42 PM

Post #2 of 9 (281 views)
  post locked   Re: Abs  

It's probably a wiring issue to the sensor. I see that a lot on GM. Not as common on Chrysler though.

They usually sell a 3 foot pigtail for replacement.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Charlymich
User

Aug 8, 2018, 8:08 PM

Post #3 of 9 (276 views)
  post locked   Re: Abs  

The wire from the new sensor goes to connector inside engine compartment. Do you think it could be wiring when I get perfect signal other than when Abs pump turns on?


Hammer Time
Ultimate Carjunky / Moderator
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Aug 9, 2018, 2:14 AM

Post #4 of 9 (256 views)
  post locked   Re: Abs  

Everything is perfect until it isn't.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
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Aug 9, 2018, 6:45 AM

Post #5 of 9 (247 views)
  post locked   Re: Abs  

I wouldn't rely on your scan tool to be accurate with the wheel speed sensors data. That information is processed inside the ABS module and then processed again in the scan tool after the data is sent over the information bus. There is going to be lag and the data points are too far apart. The best way to look at wheel speed sensor signals is with a digital storage scope.

Your scan tool also doesn't seem to have the capability of reading trouble codes even though it has that option. You might need to use the factory scan tool or a more expensive enhanced shop tool.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Aug 9, 2018, 6:52 AM)


Charlymich
User

Aug 9, 2018, 8:13 AM

Post #6 of 9 (233 views)
  post locked   Re: Abs  

Ok. Good info. I will check wires from sensor all the way to abs module tonight. Hopefully it will be bad. At least the scanner was good enough to identify which sensor to check.


Charlymich
User

Aug 10, 2018, 6:17 AM

Post #7 of 9 (200 views)
  post locked   Re: Abs  

Rewired from rf sensor to abs module. Still random cut out from sensor. The only thing I can think of is new sensor is bad, which I doubt because it acts like previous sensor. Or the abs module. Any other thoughts out there? Again suspension is tight, tone wheel looks great and aligned well with sensor. Just for giggles I Will shim sensor .010" tonight.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 10, 2018, 10:31 AM

Post #8 of 9 (192 views)
  post locked   Re: Abs  

Shimming the sensor isn't going to help. That is going to move it even further away from the tone ring.

Did your rewiring include a new plug connector?

If you eliminate everything else, that would leave the module itself.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Charlymich
User

Aug 10, 2018, 11:11 AM

Post #9 of 9 (183 views)
  post locked   Re: Abs  

I kept the old plug and where it goes into the module, it appears I have to take off front cover of module to get the connector off. I cut at module and sensor plug and soldered twisted wire in between. I might replace plug, but not going to remove or replace module. I will now consider this post solved. I appreciate all the helpful input.






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