Diagnosing ABS/VCS system problem.

[TheExplorer]

Is it possible that I could have damaged an ABS speed sensor tone ring but still not have an error code?

Vehicle: 2002 4runner
Symptoms: when in AWD and starting out slow, the truck goes into limp mode, once I gain a little bit of speed things work fine. The road surface does not matter, gravel, muddy or paved. I also have noticed that when breaking, going down a hill, occasionally, right before the vehicle comes to a complete stop, the ABS brake kicks in and "adjusts" for no reason at all. This all started after some recent work. All is fine in 2wd and 4x4 modes.

Recent work: I had to fix an engine mount perch (driver’s side) and I pulled the suspension out to allow me more space to work on it. While I had things apart I replaced the lower and upper control arm bushings, passenger side CV axle (damaged/torn boots), (driver’s side CV was pulled also to allow for working space) and a tie rod end.

I checked the speed sensor cable and that appears to be fine.

From what I have read I probably did damage one of the tone rings but I do not have any error codes.

Thoughts or suggestions?

 

[spartacus]

2001 and 02 you may have to do a zero calibration of the vsc,trac system. Also cleaning the abs sensors won't hurt. If the tone ring is damaged then it may be interrupting the vsc trac system and would have to be replaced.

 

[stunt2]

It IS possible to not to have error codes. I had same exact issues and it turned out, that front speed sensors were rised from seating surface, due to knuckle rust and caused inconsisted readings and TRAC/VSC malfunction. They were also full of rust and dirt from inside. Cleaned everyting, reseated them propery and all is good now