It's normal to hear the warning chime when shifting into 4 Low because it switches off ESP and most the safety systems, when switching off the tractional control manually or any time the car's monitoring detects an issue. A lot of the common issues like overheating brakes display a message in the in-gauge screen so in my limited experience, if you hear the chime and you see the 3 lights come on in the dash while driving but no message then it's usually wheel speed sensor or its wiring, faulty clock spring or most commonly a misaligned steering wheel. These issues which will also deactivate ESP and traction control but you mentioned the speedo fluctuating, which I hadn't personally encountered before when I had wheel speed sensor issues probably because the speedo signal comes from the transfer case, and you mentioned the radio resetting.
My backyard mechanic spidey-senses tell me it's electrical connection gremlins so my first suggestion would be to check the ground points under the bonnet first and tightening their nuts if they are even a little loose. If memory serves, there are 3: One next to the battery/TIPM on the inside of the fender, one further forward on the fender next to the ECU and one on the driver's side fender next to the reservoir closest to the firewall (I think it's the brake fluid reservoir).
On a friend's Jeep, a dealership diagnosed similar issues as a faulty ECU, which was replaced but didn't fix them. I reckon it was simply a loose TIPM connection because the issues never appeared again after we removed and reinstalled the TIPM to clean it and its plugs. It seemed a daunting task but it wasn't a difficult job that needed specialised tools, especially because we watched every Youtube video we could find on the TIPM and we used my dual battery kit instructions to help us out.
You might still have a separate wheel speed sensor issue though so I would suggest looking over the wiring, especially at the plugs looking for exposed wire or possible broken connections and near the rear bumpstops looking for crushed wire sleeving (it caused an intermittent connection issue for me).
May I offer some more unwarranted advice? Stay out of the mud. I have had to replace 4 sensors over the years, every time after driving through Glasshouse mud so now I stick to rock crawling.
__________________
The average human walks 1,500km per year and drinks 83L of beer which means we're getting 18km/L.
|