TRAC overactive only when in multimode 4WD
 

2002 Limited 4WD with the Andy Mod 2.0 installed

A couple weeks ago I noticed my ABS sensor going off randomly. Pulled both front sensors, one was covered in rust flakes, so I cleaned it and reinstalled. I wasn’t able to seat the sensors as perfectly flush as before, but everything seemed to work fine. The ABS problem didn’t happen again.

A few days ago I was stuck in traffic and pressed the 4WD button to give the transfer case a little work out. I quickly noticed that TRAC was engaging almost every time I accelerated from a full stop - which was a lot, since I was in stop and go traffic. It cut a little power but wasn’t drastic enough to make driving difficult or unsafe. More annoying than anything. I turned off 4WD and the problem disappeared. Yesterday I tested it again in 4WD and the problem is still there.

Might I have screwed something up in the ABS sensors when I reinstalled them? Possibly related, I noticed that there is a lot of rust on the CV axle in the ABS sensor hole. Could that be related to my issue? I haven’t used 4WD in a while, so this issue could have been developing well before I noticed it.

Rust:

https://i.imgur.com/VWcq4y6.jpg

Reinstalled sensor, not perfectly flush:

https://i.imgur.com/GPuDtsl.jpg


I’ve read about similar issues with the VSC getting fixed with a yaw sensor recalibration, but I assume that’s not the source of my problem, since I’m losing power when driving in a straight line. Obviously I can use the Andy Mod switch as a work around for the time being, but any ideas for a more permanent fix?

Can't help with your problem, I'm not familiar with that system as mine is older.

Just wanted to say that a little silicon grease smeared around the sensor hole and o-ring will make things go back together easier and keeps it from sticking in the future.

Good luck figuring it out.

Thanks! I'm going to check it out again this weekend and I'll reinstall as you suggested.

Still battling the TRAC issue. I’ll spare you all from the novel, but I’ve replaced the left front ABS sensor and done a zero point calibration for the VSC.

Where I’m at right now: TRAC still engages without fail while accelerating from a full stop, if I’m in 4WD. In all other scenarios, there’s no issue. I’m not getting any codes from the engine bay diagnostic box.

My current theory: the rust and debris on the ABS sensor was causing my ABS issue earlier. I’ve done enough cleaning on the sensor and the ABS tone ring to reduce the rust to the point that my ABS issue has gone away. However, the TRAC (for some reason) is more sensitive and the remaining rust is still triggering it. The reason it only happens in 4WD is that the ECU (for purposes of engaging TRAC) doesn’t care about front wheel speed in 2WD.

I found a bunch of posts on the forum with people complaining about a similar issue (TRAC engaging from a full stop while in 4WD) but there’s no suggested remedy (other than the AndyMod).

As I see it, these are my options, none of which seem great:

1. Get a code reader and see what that shows. I noticed Scotty Kilmer has a video for this, but the one he recommends gets bad reviews on Amazon. Does anyone know of a reader that would show wheel speed from each sensor for our trucks?

2. Pull the knuckle, find the source of the rust and clean, replace ABS tone ring (and install new bearings while I’m at it).

3. Ignore for the time being, use the AndyMod when in 4WD, occasionally clean ABS sensor of rust to avoid ABS issues.

1 seems pointless if I’m going to have to do 2 anyway. Also I’m not against investing in tools but also not trying to spend too much money with a recession looming.

As a relatively inexperienced shady tree mechanic, 2 is a bit out of my comfort zone, also I’d have to buy a press, so I’d really prefer to avoid this route if possible. Cost would be roughly $300 in parts, $200 in tools.

As for 3, if something is rusting in the knuckle, it seems like I shouldn’t ignore it. But what do I know?


Has anyone else seen rust on their ABS tone ring like this? Is it something to be concerned about?

I hate to be the guy that bumps his own thread, but can anyone tell me if the rust on that ABS tone ring is something I should be concerned about? I've scoured this forum and the internet and can't seem to find an answer.