Abs module goes out after 5 minutes

[Alexio Auditore]

Ok guys I need some input. I just got my abs module back from Module Masters and put it in the truck and what do you know, no abs light, motor isn't continuously running, Yes! So stinking happy.  Drive about two miles, getting off the freeway and look down and see the abs and brake light on. Crap. So I get out of the truck,open the hood... The motor is running. So module Masters says they will take of it, they didn't hassle me whatsoever, which is nice. But my question, could something be going through my electrical system and causing that relay or whatever it is to fail? I'm guna order a fluke ( either 114 or 115, not sure what would be better) and test the alternator for ac noise. But can it be another issue? Two years of the abs light staring at me, I want it gone for good.

[Mopar1973Man]

I would suspect it to be AC noise issue if anything. Being mine was both AC noise and a bad passenger wheel tone ring.

[Alexio Auditore]

Passenger wheel tone ring? What is that and what can it do? The ac noise can fry other things too right?

Edited June 30, 2017 by Alexio Auditore
Sounds nicer

[Alexio Auditore]

Well I got my multimeter today and tested my alternator. 0.03 was the reading I got with electronics off. 0.06 with air conditioning, music, and lights. I'm banging my head against the wall trying to figure out what else it could be. I don't want to get the module back and put it back in the truck just to have it go out again.  I tested voltage and it was 13.7 at the alternator too, so I think the alternator is ok. What else do you guys think it could be? I don't think it had anything to do with the repair either, it worked for a few minutes and then the  light came on.

[SilverMoose]

Is your power steering fluid low?  It can't hurt to ask even if its OK.

 

L8tr

D

[Mopar1973Man]

There are only a few things that trip the ABS light that I've found...

• Bad speed sensor(s)
• Bad tone-ring or misaligned tone-ring.
• Metal debris in the tone-ring or stuck to the end on the sensor.

 

[TFaoro]

35 minutes ago, Mopar1973Man said:

There are only a few things that trip the ABS light that I've found...

• Bad speed sensor(s)
• Bad tone-ring or misaligned tone-ring.
• Metal debris in the tone-ring or stuck to the end on the sensor.

 

I would suspect you have something going on with one of these ^^^^^^

[Alexio Auditore]

I'm not familiar with the tone rings. Are they on each wheel then? What's the best way to check them?

[dripley]

I think the only way to see them is to pull speed sensors. Then shine flash light in the hole. The sensors pick up notches in the tone ring to get a speed reading.

[Alexio Auditore]

Ok. So there will be a total of 4 then, one on each wheel?

[Royal Squire]

I believe there is one on each wheel in front and one on top of differential in rear. 

[Mopar1973Man]

One in each front wheel bearing. Then one in the top of the rear diff housing. Only 3 sensors.

[dripley]

Yes, what they said.

[Alexio Auditore]

Ok. I'm going to have to look at it then. So if a tone ring is bad, would that cause the module to have to get re-read repaired then? I got the module back today and they replaced the mofet again. ( I think it's a relay inside?) I'd think if the the sensor wasn't getting a correct signal from the tone ring, it would just give a code and abs light would come on. I'm just trying to understand how this all works, I appreciate all the help you guys have given.

[Chris O.]

12 minutes ago, Alexio Auditore said:

it would just give a code and abs light would come on.

You should get the code no matter what that's the best way to check the issue.
Currently you are limited to the dealer unless you know someone with DRBIII tool ?

 

By the way it's not a relay:

MOSFET - Wikipedia

The metal–oxide–semiconductor field-effect transistor(MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET). It has an insulated gate, whose voltage determines the conductivity of the device. ... In "depletion mode" transistors, voltage applied at the gate reduces the conductivity.

[Alexio Auditore]

Good to know. I learn something new everyday on this site, thank you for the clear up. if it's not getting the correct reading from the tone ring, I'd get a code that only the dealer can read (which I read on here was like 6000 dollars to buy one myself). So if it is a bad tone ring, it will cause the mofet to fail in the module then? 

[Chris O.]

16 minutes ago, Alexio Auditore said:

So if it is a bad tone ring, it will cause the mofet to fail in the module then? 

No.

I'm not sure what the issue is but that's definitely not the tone ring.
Trust me I fix this issue back in 2010 on my truck.

 

A bit of History.

NOTE: This was before anyone was offering a fix for this.
Back in 2010 the dealer quoted me $1,000 to fix the ABS issue and i was like screw this I know enough about electronics to fix this myself so I took the ABS module apart and replace the transistor myself.

Edited July 9, 2017 by Chris O.

[Alexio Auditore]

Ok. Ya I heard buying a new one is ridiculous. Well, I'm guna check the tone ring just to make sure it's ok still, but then I'm not sure what else can be done. I just don't want to put it back in the truck and have it go out a short distance later.

[015point9]

Not sure if this relates to your problem or not but easy to check.  About 5 years ago my ABS light would came on or flicker on and off.  Sometimes when cold ABS light would light up and other times it didn't. Thru lots of playing around, it turns out the wire connection right above the rear diff would comes loose, but only after driving awhile.  Maybe the plastic connection warms up a bit after the diff warms up or just wiggles loose from our bumpy roads, I'm not sure?  At any rate, the connection wiggles loose one reason or another.    Mine looked tight but connection was loose enough to set off light. 

 

I still haven't fixed it right.   I put a big screw type radiator hose clamp around it just as a test.  Test worked so good that I haven't taken the time to fix it right yet.  

 

That connection is one of the things on my list to get when I find someone parting out their 2nd gen.

Edited July 9, 2017 by 015point9

[Chris O.]

Quote

Ok guys I need some input. I just got my abs module back from Module Masters and put it in the truck and what do you know, no abs light, motor isn't continuously running, Yes! So stinking happy.  Drive about two miles, getting off the freeway and look down and see the abs and brake light on. Crap. So I get out of the truck,open the hood... The motor is running.

 

 Kelsey-Hayes 325 EBC; All wheel ABS system:

If ABS pump runs continuously even with ignition key off, the culprit is an electronic control module, which uses a transistor to switch the pump on and off, rather than a relay.  
simply unplugged the 2 pin connector at the pump, until the ABS can be repaired.