ABS module troubleshooting

Tiny
BOBBY MALAER
  • MEMBER
  • 2008 JEEP GRAND CHEROKEE
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 164,000 MILES
I need some advice here with an ongoing ABS issue. Quick background, ABS, ESP/BAS, brake lights on dash showed up randomly (vehicle gets driven once every few weeks and had been parked, no recent mods or anything). Checking codes, wheel speed sensors and a few other things were showing. Anyway, all four sensors changed and even a new ABS module, no change at all in codes.

I have Bluedriver to read codes, but whenever I try to clear them they will never go away, not even for a moment. Ignore the TPMS codes, I disabled those with my tuner. Sometimes all four wheels speed sensors show fault, sometimes three of four.

Now I am double checking all my wiring. Wiring to the sensors checked out good, as well as the sensors themselves.

I am getting proper voltage at the module, but am concerned about possible shorting or voltage drops under load.

I have got the negative battery cable disconnected, and the main plug at the ABS module disconnected.

I put one lead on ground (body and negative cable showed same results) and checked the pins on the ABS module plug. Here is what I found.

Pins 1 and 32 are constant power, and showed 0.5mOhms to ground. Pin 8 is key on power, and showed 5.6kOhm to ground. Pins 12 & 13 are my canbus and showed 18.9kohm to ground. All other pins were OL which I expected.

Ground pins to actual ground are perfect at 0.2.

So, are those values too low to be concerned with, or is anything other than infinite a problem? I should know this as my full time job deals with similar stuff but I am having a brain fart.

Also, if those values appear good, then any other suggestions? I thought maybe a clock spring, but in this generation of jeep you would usually see steering angle codes and steering wheel centering codes as well.
Tuesday, November 22nd, 2016 AT 11:51 AM

3 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Tuner? A lot of times those are the trouble. If you have one that stays constantly in aldl then unplug it for a while and see if it clears. But what your codes have I think may be an can/bus problem with the U codes. Or maybe a tpim module. Looks like the PCM and ABS are not talking to each other like they should.
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Tuesday, November 22nd, 2016 AT 1:18 PM
Tiny
BOBBY MALAER
  • MEMBER
  • 2 POSTS
Thank you. For what it's worth, the tuner is a superchips flashpaq, doesn't stay plugged in. I used it to disable TPMS as my aftermarket wheels don't have the sensors in them and I was tired of the tire pressure warning on the dash. I'll definitely start look into the TPIM module, looks like they were known to have issues on this generation of vehicle.
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Wednesday, November 23rd, 2016 AT 5:26 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I looked up the codes to see if was what I suspected and it is the one deals with abs and final drive module and other deals with what I have posted in pic which relates to abs or a bad abs/pcm. If you can track down bus problems that may fix it. But for bus problems it 's better to have a pro look at it for a short/open
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Wednesday, November 23rd, 2016 AT 6:43 AM

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