ABS light on

[Steelart99]

2004 Jeep Liberty Limited 3.7L engine

My ABS light is on with the following DTC codes showing up:
02 Left Front Wheel Speed/Signal failure
03 Right Front Sensor Circuit Failure
04 Right Front Wheel Speed/Signal failure
08 Rear Right Wheel Speed/Signal failure
09 Hydraulic Pump Circuit Failure
12 Incorrect Tone Wheel

My ABS light was somewhat intermittent for a short time, but finally just stayed on. Both ABS fuses check okay. I don't see any damage to any wires (no chew marks). Clearing the ABS light does nothing (light stays on). I couldn't get my rear sensor connector off the sensor ... grrrrr ... I sprayed it with WD-40 and will try again later.

Based on the codes above, all my sensors are showing up as failed, but I doubt they'd all fail at one time. So, should I suspect the Hydraulic Pump Circuit failure as the root cause? For the first time I read about removing that circuit and re-soldering some connections but don't want to just jump right into doing that without having some better brains help me out.

Any recommendations on how to test/address this will be appreciated.

 

[seafish]

It’s easy enough to disconnect and then Check the resistance of the sensors with a DVM ohmmeter

I forget what the actual resistance of the sensor is supposed to be but If there is no resistance at all, thst means the sensor has failed.

 

[Steelart99]

It’s easy enough to disconnect and then Check the resistance of the sensors with a DVM ohmmeter

I forget what the actual resistance of the sensor is supposed to be but If there is no resistance at all, thst means the sensor has failed.

Yeah, I think I can get to the front two fairly easily. I couldn't get the rear connector off (there is only one on the back end of the Liberty). Tomorrows job ... too hot today.

 

[u2slow]

Do you feel you need ABS? Our 2005 doesn't have that option.

 

[Steelart99]

Do you feel you need ABS? Our 2005 doesn't have that option.

Sometimes in icy/snowy weather it has engaged. Other than that ... nope. There's really no way to know if it "helped" when it did engage. I just figured that I would fix what's broken if it didn't cost too much in $$$ or time.

 

[seafish]

If the odometer still works 100% of the time then the single rear sensor is still good.

That said the pigtail on the rear sensor tends to fail from wire fatigue , in which case the ABS light will come on and the odometer stops working

 

[blackhawk]

As far as I know, kj abs sensors are not resistive.
Check if abs module is getting 12v and if ground is ok

 

[seafish]

As far as I know, kj abs sensors are not resistive.
Check if abs module is getting 12v and if ground is ok

AFAIK they are essentially Hall effect sensors which means that they have some resistance and if they test as an open circuit they have failed

At least how they work on my 2005 Dodge Ram

 

[seafish]

Oops double post

 

[Steelart99]

If the odometer still works 100% of the time then the single rear sensor is still good.

That said the pigtail on the rear sensor tends to fail from wire fatigue , in which case the ABS light will come on and the odometer stops working

Interesting!!! Odometer is working fine and the wire looks okay ... at least externally.

 

[Steelart99]

As far as I know, kj abs sensors are not resistive.
Check if abs module is getting 12v and if ground is ok

The module was likely going to be my next check for broken internal connection. Didn't think to just check 12V and Gnd. DOH!

 

[Steelart99]

AFAIK they are essentially Hall effect sensors which means that they have some resistance and if they test as an open circuit they have failed

At least how they work on my 2005 Dodge Ram

From what I've been seeing on UTube, it appears that I can connect a multimeter to the sensor connector and then spin the hub. I should see changing voltage as I do so to indicate a functional sensor. That said ... an open circuit would be far easier to check.

 

[seafish]

In fact on my 05 Liberty the pigtail wires on the rear sensor were broken UNDERNEATH the insulation…but I knew they were breaking because the odometer would intermittently drop out…it is a fairly common problem inherent to the design of the pigtail and how it attaches to the sensor on the pumpkin and the wishbone UCA.

All that said if your odometer is working all the time then so is the rear ABS sensor

 

[u2slow]

I just figured that I would fix what's broken if it didn't cost too much in $$$ or time.

Fair enough.

Sometimes I get way far into chasing something, and then realize, wtf am I doing? Abandon and move on...

 

[KJowner]

Fair enough.

Sometimes I get way far into chasing something, and then realize, wtf am I doing? Abandon and move on...

You're lucky, we have an annual inspection so abandoning most things isn't going to work, even stupid things like TPMS is a fail.

 

[u2slow]

You're lucky, we have an annual inspection so abandoning most things isn't going to work, even stupid things like TPMS is a fail.

Seems crazy with factory-optional equipment. ABS and TPMS would be optional in 04 & 05 KJ.

We have an inspection process here for personal vehicles, but not annual. Only if law enforcement writes you up an order to have one, or bringing in a vehicle from outside the province.

 

[Steelart99]

In fact on my 05 Liberty the pigtail wires on the rear sensor were broken UNDERNEATH the insulation…but I knew they were breaking because the odometer would intermittently drop out…it is a fairly common problem inherent to the design of the pigtail and how it attaches to the sensor on the pumpkin and the wishbone UCA.

All that said if your odometer is working all the time then so is the rear ABS sensor

I said my odometer is working ... but really, I guess I just mean that I haven't noticed if my odometer isn't working. Not quite the same thing. I didn't have time to work on it today, but you can bet checking my odometer will probably be the very next thing I check.

 

[seafish]

Another way to tell if the odometer is working only intermittently is if you hand calculate your MPG and it’s much less then usual, but that’s assuming you usually track MPGs.

 

[ikuo78]

I remember reading somewhere that it's more likely to light up when the battery is weak.
Mine also has the ABS light come on occasionally but goes out within a week.
There must be a leak somewhere.
On mine, the light always comes on if I spray silicone on the right front ball joint boot and it splatters around the area.
It seems to be sensitive to even the slightest voltage changes.

 

[Steelart99]

I remember reading somewhere that it's more likely to light up when the battery is weak.
Mine also has the ABS light come on occasionally but goes out within a week.
There must be a leak somewhere.
On mine, the light always comes on if I spray silicone on the right front ball joint boot and it splatters around the area.
It seems to be sensitive to even the slightest voltage changes.

Interesting! Although I put a new battery in this Jeep last year, I don't drive it very often as it is not my primary vehicle. I was getting a low voltage "error", but the battery has started the vehicle without much effort and I have driven it frequently over the last couple of weeks. I'm still getting the ABS light.

I've been busy this past week and have not had a chance to get back to this issue. Hopefully, this week I'll be able to chase down the various solutions that you all have proposed.