I've read through the forum and I've seen this topic a few times.
No-one unfortunately posts what the fix was for this issue.

Example: viewtopic.php?f=5&t=57905

Can someone confirm that there is a problem with the rear diff speed sensor if the symptoms are
ABS light on, Odometer does NOT work, Speedo does work, Tach does work, No brake light.

I replaced the rear speed sensor and pigtail and no difference.
Before I crack open the rear diff to see if there is a problem there I wanted to check to see what others thoughts were, or anyone who had this issue and fixed it.

Went to O'reilly's to have the ABS codes pulled.

20FE
3EFE
28FE
30FE

Codes are in this thread: viewtopic.php?f=5&t=87477

Doubtful all of the speed sensors are bad and the battery.

Hello Timmy;
I had the same conditions several times through the years. The first one was the rear signal, some defective wiring repaired with spade connectors. I had the repair replaced with soldered joints. The second time was some of the front sensors.
A question; Do you do any off-roading? The reason is that the technician said that the front sensors were damaged by rust in the tuning wheels from mud and water fording.
In another occasion the two front sensors were replaced, but because the first replacements has some issue with the wiring.
On the rear one I discovered that I had some faulty connections at the wire connector to the sensor. The wiring was moving up and down too much and loosened the connection. Also created by the off-roading adventures. Some zip-ties and securing the wiring so it does not move that much, it have to move up and down with the differential, minimized the occurrences. I know that will sound weird, but what I do some times with the car moving at some speed, is to shift to neutral, shut the ignition switch off and restart the engine, and then shift to drive. The ABS light will reset itself if the loose connection had time to restore to a tighter position. Not a remedy, but a "band-aid" until I get to my destination and get under the car and hand tight the connection again.
This happens mostly in the fall, when the temperature changes day to night start getting colder. not much during winter to summer.

Hope this will help.

_________________
Sergio05CRD

Thanks @SergiodelCastillo

I don't do a lot of 4 wheeling. A few dirt roads in the mountains, but that's about it.
I haven't driven this Jeep much since COVID, so it's barely been out.

I went on vacation and came home and the left front tire was flat. I blew it up and probably a month later it was flat again.
I changed it with my full size spare and I'm pretty sure it was right around that time the light came on.

I'm going to pull the front tires off and do some continuity checks on the wiring to see if there are any breaks.

Was hoping the odometer and trip meter not working was a sign about which wheel it was.

I purchased this Bluetooth OBDII scanner from Amazon. It was about 40 bucks.

https://www.amazon.com/dp/B09C8GBB2R?ps ... ct_details

It read the ABS codes and stated:

20
Right Front Sensor Circuit Failure.





Well...that's pretty specific, and actually seems to fall in line with other posts I read of people losing the odometer and trip when this sensor goes out.

This OBDII scanner can also apparently trigger the ABS bleed procedure although I haven't done it yet.
If the code is right *and* it had the ability to run the ABS bleed job....this thing will be sweet,and will have saved me a bunch of money going to a stealership for a proper brake bleed.

I'll update once I've had a chance to run it to see if it actually works.

Interested to know how things turn out. I recently experienced a similar issue with my Jeep. But the ABS light also came on.

I replaced the rear speed sensor with no improvements. I have been going to pulled the front wheels and check, but I haven’t had time.

I wasn’t aware there was a trigger that needed to be turns off when bleeding the breaks. This probably explains why my brakes are so spongy and I can’t get any improvement with bleeding them. Even with a vacuum.


Sent from my iPhone using Tapatalk

Well, I realized today after I saw what the front sensor looks like that I ordered the incorrect sensor.

The front sensors have no disconnect like the rear one. Their pigtail is built-in.

What I did realize though, is that I can take the rear sensor, and plug it into the plug that the front sensors connect to (in the engine bay).

I did this for the front right connector, reset the ABS light, and it didn't come back on.
I hooked the original sensor back up and the light immediately came back on. Resetting it had no effect, it came right back on.

So...front right speed sensor it is, and the best tool for your toolkit for testing which sensor is bad is an extra rear speed sensor.

I also saw a 3 volt drop on my multimeter in the line when I jumped between the connectors, so there is too much resistance in the front right sensor.
The other sensors lost almost no voltage when connected.

New front right speed sensor showed up today.
https://www.amazon.com/dp/B09G6M93DH?ps ... ct_details

(They are a little cheaper on ebay)

Took about 25 minutes to get the tire off, caliper /w rotor attached off, and speed sensors swapped and everything put back together. (It helps when you've done it once).

I can confirm that if your trip meter and odometer go out and you get the ABS light it is the right front speed sensor.

This weekend I will see if this new USB code scanner can actually do an ABS brake bleed test.