...need to troubleshoot ABS light? - JeepForum.com

 
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post #1 of 14 Old 09-21-2009, 11:32 PM Thread Starter
lvum4x4
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...need to troubleshoot ABS light?

I have a nice service manual and wouldnt you know, there is no Brake section! I must have missed that section when I printed everything off (use a PDF file). I have the ABS light on and went to program my tire size with the Superchips programmer and because the ABS light is on I can not calibrate my tire size. So, now I need to troubleshoot the ABS light. Does anyone have any advice or suggestions?

I am not sure where to begin? It is my guess I have a bad sensor or something so I think I need to unplug each sensor and put a volt meter on them to find the bad one? Sound right? Any other tips, suggestions or things I should try first? I dont have any history as the light was on when I bought the Jeep.

Thanks for any help...

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post #2 of 14 Old 09-21-2009, 11:42 PM
ratmonkey
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You need a drbiii tool to retrieve the codes from the abs computer. Pretty much grabbing at straws, in the dark otherwise.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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post #3 of 14 Old 09-22-2009, 02:39 AM
sandman
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there may be air in the system.

1993 Jeep ZJ. 4.0
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post #4 of 14 Old 09-22-2009, 11:06 AM
Texas98ZJ
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I took mine in for the ABS light and Jeep charged $75 for the diagnosis - bad ABS sensor. Much better than the time I would have spent chasing a problem...
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post #5 of 14 Old 09-22-2009, 11:18 AM Thread Starter
lvum4x4
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I dont have any scanners so I will likely have to do that. I just replaced all the brakes so I wish I would have thought about it then as I already had the rotors off.

I will see if I can get a local shop to diagnose it for me. I am spoiled becuase I save so much $$ doing things myself that it hurts when I have to pay someone for something like this.

Thanks
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post #6 of 14 Old 09-22-2009, 02:39 PM
dougy147
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I've seen ABS sensors tested on other vehicles before by back probing the connector and spinning the wheel with the key on. The oscillations in current are so fast that you need a graphing meter though, which cost a lot more than that dealer diag fee.

I believe I saw a scanner in advance auto the other day that would pull ABS codes, I don't know how much it was though. I'd look at it this way: just paying to have it done will probably be cheaper than buying the necessary tools to diagnose....and easier too!

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post #7 of 14 Old 09-22-2009, 04:16 PM Thread Starter
lvum4x4
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I have an appt to get it scanned Friday ...hopefully it will not be an expensive fix.
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post #8 of 14 Old 09-26-2009, 04:09 PM Thread Starter
lvum4x4
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Well, we scanned it and got some erratic readings? It originally said something about the back but the next time he ran it, it gave him a:

P1793 TRD Link Communication Error

Anyone have any experience with this code? I was expecting an ABS error and got a trans/speed sensor error? Can they be related?
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post #9 of 14 Old 09-26-2009, 09:17 PM Thread Starter
lvum4x4
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...bump

Anyone have any advice on this code? I am not sure where to start? I cant calibrate my speedo until I resolve this ABS issue

I appreciate any help.
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post #10 of 14 Old 09-28-2009, 05:18 PM Thread Starter
lvum4x4
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Nobody out there has ever seen this code?

I have tried searching the web and cant seem to find anyone in a Grand Cherokee that has experience with this code?

Bumpity, bump?
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post #11 of 14 Old 10-23-2009, 04:33 PM Thread Starter
lvum4x4
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Well, I figured I would try again since I have some new information about my ABS issue.

We went wheeling and of course flexed out the rig pretty well and also used 4Lo quite a bit througout the day. Well, when we finished and I put the TC back into 4HI (all-time), my ABS light went off? WTF? I was stoked but about 1/4 mile down the road, I hit a good size bump and bam! Light came back on? I have since tried going in/out of 4HI/4Lo to replicate but have not been able to get the light to go off again. I am going to keep my Superchips programmer in the Jeep just in case it does it again so I can calibrate my speedo before it comes back on but I would like to find the bad connection and fix this once and for all...

So, this tells me that everything likely works but that I have a connection problem so now I am wondering where should I start? Are there any speed sensors in the TC that would have triggered it or do you think it was just all the flexing? The light didnt go off until I shifted back into 4HI so I am thinking there must be a sensor in the TC? Any ideas?

Kevin Bentley

Build:
http://www.jeepforum.com/forum/f197/bentley-project-wj-build-thread-870037
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post #12 of 14 Old 10-24-2009, 10:27 AM
jeep_zj98
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ABS is one of the topics people here dont seem to talk much about. I have posted few questions and have never seen a reply. I got a code 30 - ABS pump circuit bad or something like that.

These are the suggestions I found after a major search on the internet.
1. Clean the contacts.
2. Check the fuses.
3. Check power at the pump. I get 8.45 volts, not sure if that is correct.
4. Like someone said here, check the current sent by the sensors.
5. Clean the sensors and check the air gap between the rear sensor and the tone rings.

I did all the above and I just need confirmation on how much voltage the pump needs (volts at the pump connector). If it is 12v, then I know that the CAB is not giving out enuf voltage and I may end up replacing the CAB.

Hope this helps you in your search to fix the ABS.
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post #13 of 14 Old 10-24-2009, 10:42 AM
cmonson
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check the connections at the ABS module. Sounds like something isn't making a good connection, thus when you hit a bump, it disconnects.
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post #14 of 14 Old 10-24-2009, 08:13 PM
dougy147
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Quote:
Originally Posted by jeep_zj98 View Post
ABS is one of the topics people here dont seem to talk much about. I have posted few questions and have never seen a reply.
I agree. I think it's just because they are not the most common problems and a lot of times require some expensive/specialized equipment to properly diagnose without loosing one's sanity.

That said, I have nothing to offer that hasn't been said in the prior 2 posts...except a bump

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