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-   -   2002 WJ 2.8 diesel Grand Cherokee (http://www.jeepgarage.org/f51/2002-wj-2-8-diesel-grand-cherokee-67855.html)

Tony Norton 11-12-2013 06:18 AM

2002 WJ 2.8 diesel Grand Cherokee
 
Hi All,

popped out in the Jeep this morning and noticed that the "ABS" light stayed on.

There are no detectable problems with the brakes. Less than 2000 miles ago, as a result of an MOT failure of the handbrake, I had new disk/drum assemblies (rotors), pads and shoes fitted at the rear.

According to the manual I have "The MDS or DRB III scan tool is used to diagnose the ABS system.", which seems to indicate another trip to those robbers at the local Jeep dealership.

That is unless............somebody out there can say "..I had that happen and the cure was a simple matter of say, Fuse No. "x" having blown or the connection at such and such a location being loose or etc. etc."

Any ideas anybody?

Cheers

Tony N

Frango100 11-12-2013 09:44 AM

Re: 2002 WJ 2.8 diesel Grand Cherokee
 
Hi Tony, I would start checking the wheel speed sensors for dirt buildup and the connectors for fit/corrosion/moisture. Just follow the wiring going to each wheel and you will find the sensors.
Also check fuses 4 and 25 in the PDC and 19 on the JB.

Tony Norton 11-12-2013 12:26 PM

Re: 2002 WJ 2.8 diesel Grand Cherokee
 
Thanks for that Frango,

I guessed, when I saw that you were online when I posted my query, that I would get something useful from you.

Thanks a lot mate.

Tony N :thumbsup:

Tony Norton 11-13-2013 11:44 AM

Re: 2002 WJ 2.8 diesel Grand Cherokee
 
Hi Frank,

according to the manual, and my own observations after removing a wheel, the ABS sensors seem to be retained by a single, 8mm head, bolt.

My guess is that the sensors are Hall effect transistors that sense the passing of "teeth" on the cog wheel. Is the place where one can get a dirt build up, between the sensor and the cog wheel? If so, does removing the small bolt allow you to get to the sensor itself and clean it up?

There are no signs of damage to the wiring, which seems pretty well protected, so I'm hoping a clean up may do the job. If not, I suspect that the sensor and its wiring come as an expensive unit :mad:

Cheers

Tony N

P.S. will you be at the final GP in 10 days' time?

Frango100 11-13-2013 12:31 PM

Re: 2002 WJ 2.8 diesel Grand Cherokee
 
The sensors are indeed hall effect sensors. Don't believe that you have to remove the sensors, you should be able to clean the sensor and tooth wheel with some water and a brush. The problem can still be something else then a sensor. The ABS controller itself for example. You could check the connector on the controller.

Tony Norton 11-18-2013 08:19 AM

Re: 2002 Grand Cherokee 2.7 CRD, ABS sensors - resetting
 
As previously stated, my ABS is playing up. It seems that a sensor failure is quite probably the cause of this. Having sussed out where the ABS sensors are located I propose to remove, clean up and replace them, one at a time.

So far I have just done the left rear, which was covered with a greasy gunge.

What I would like to do is reset the system after each clean up so that I start from scratch each time.

Question is: - can I reset the system without the use of a scanner?

After resetting I seem to remember there is a trick with the ignition key that identifies any error codes, but I can't remember what that is. Can anybody help with this please?

If any of the sensors need replacing do I really need to buy 60's worth ($75) of cable and sensor assembly? Is it possible to disconnect the sensor, which is only a Hall effect transistor, from the cable assembly, and replace just that part?

Thanks in anticipation for any advice offered.

Tony N

Frango100 11-18-2013 09:11 AM

Re: 2002 WJ 2.8 diesel Grand Cherokee
 
The CAB (controller antilock brake) will do a static test each time the ignition is switched on and a dynamic test when 30 kph is reached. The keydance will not show the CAB stored faults, a DRBIII or equivalent scanner is needed for this. Eventhough the memory will not be errased when a fault is solved, it should extinguish the ABS light on the instrument panel. It can be that you have to drive first for the system to do the dynamic test, for the ABS light to go out.
You could measure the resistance of each sensor to see if one is bad. I found values in between 500 ohm and 2000 ohm to be ok. Also clean ach connector, because corrosion on pins will already change the resistance.


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