ABS, traction control, parking brake light all on - my solution

My ABS, traction control, parking brake light have all flipped on during a long drive between cities in the middle of a BC winter, but the truck drove fine (and I could even slide in the snow now without traction control!). When I turned off the truck and turned it back on, the lights would all go off. This became a more common occurrence and the length of time all these lights were popping on would increase, until now, 5 months later, they are on all the time.

Initially I scoured these forums and seen its likely an ABS sensor failing, so I sorta lived with this issue and would deal with it later (later being now). Using these forums as guidance, the problem could be a few things, in sorta an increasing cost to fix:

- ABS sensor broken
- wiring harness damaged
- wheel bearing shot, making the toning ring become out of alignment
- axle seal failing causing the bearing to fail causing the issue

As I was blind to the actual problem, I first looked around my wheels and ABS sensors and everything seemed to be fine. No oil thrown about my wheels from a failed seal, and the wiring harnesses looked fine. I next pulled the error code by using a wire (it was twist tie actually) on the OBD2 reader (under the dash where your left knee sits), connecting the two pins while the truck is off, as explained here:

https://www.tacomaworld.com/threads/cleaning-tone-rings.230586/#post-5420260

I was wary of this method to read a code but was too cheap to buy a scanner until I really need it, and this method worked very well. The ABS light blinked out:

33 : RR ABS sensor malfunction
38: metal stuck to RR ABS sensor

So I pulled out the RR ABS sensor, which looked fine, but I just blindly ordered one thinking this would fix the issue. The Chinese knock offs on ebay are like $14, or you can buy the OEM which is over $200, I went with China here. When it arrived, the sensor looked -identical- to what I pulled out of my truck. Swapping them did nothing to relieve the error codes or turning off all my dash lights.

So this was a lesson learned: make sure if you buy a part that the part you are replacing is actually the problem! From this point, I wanted to make sure the ABS sensor was really the issue, so I swapped the RR and RL ABS sensors (I didn't screw them in) and ran the codes: it was still the RR error codes. So the ABS sensors are likely fine I assumed, and it must be either something to do with the toning ring on the RR side, or the wiring harness. The wiring harness looked great but that may not mean anything. I borrowed a continuity meter from work, and unhooked the wiring harness from the two rear ABS sensors and where the harness connects to the main harness (located above the spare tire). Checking the continuity of each of the 4 wires: one had no continuity and it was on the RR side..

I took the wiring harness completely off for closer inspection and everything looked great. But I did put in new leafs 2 years ago and maybe I stretched the line out and the failure point would likely be inside the ABS sensor connector. So I took the connector apart carefully and....


Right where it bends around the plastic on the inside, the insulation wore through and the wire was replaced with green copper oxide. There was dirt packed all inside this connector, so mild vibration would have done this in over time. I double checked and this was the wire that had no continuity.

This is beyond my ability to fix, I'm no electrician and the wear is in a weird spot, so I am now ordering a new wiring harness.

I like to do things myself, if anything, to save money. I couldn't image what this would have cost at a shop to figure out. I am not a mechanic or anything by any means (chemist by trade), but this forum gives me the opportunity to learn things about my truck, and with a little luck, fix things or upgrade things myself. This is the first time I ever wrote anything up - I hope it helps some other noob like me out.

 

Great write-up!

 

Thanks for taking the time to show folks how to troubleshoot. It's a valuable skill that does not come naturally to most.