JKU rebuild

Hello everyone, I am in the process of rebuilding a salvage jeep. At this point I have repaired all mechanical problems and its re-titled. The only issue remaining is the traction control and ABS light are on. When I drive it without hitting the traction control OFF button on the console the jeep tries to fight me when I accelerate like its applying the brake and disabling the gas pedal. After research a bad wheel speed sensor seemed like the most likely cause, so I brought it to a shop to conform my theory and the got a code for the driver side rear sensor, sense the quoted me a ridiculous price for a $20 part I decided to changed it myself. Afterward to my surprise it did not change anything, so called a driveway mechanic to help with it, we discovered that the sensor was was working and reading just fine by switching the wires of the rear right and left wheels while having his scanner hooked up to the jeep OBD/II port reading the wheel speed. So my prediction is that there is something wrong between the ABS computer and the wheel speed sensor, I checked the connectivity of the wires from the terminals at the end of the cable to the pin connector at the computer side and found a connection but only to one pin from both wires of the wheel speed sensor. I do not know if that is normal or if that means there is a short between the wire somewhere. If anyone has knowledge on ABS, ESP systems or electrical work I could really use some help brainstorming on were to go from here. Thank you.

jedg

Did the error follow when you switched the wires, i.e., you got an error on the left rear? That would indicate a connection issue.

JKU rebuild

Thanks for the response. Yes, when we had the monitor hooked up it showed zero wheel RPM on the driver side rear (the bad one according to the code) when I was spinning the rear tires, while the passenger side rear showed RPM. After switching the wires the driver side rear showed RPM and the passenger side rear did not show any movement.

resharp001

Afraid I can't add a whole lot of troubleshooting here, but curious where the main damage was that originally totalled the vehicle. Any place that would have logically impacted this wiring? I know that is a real stretch, but it's an odd thing you have going on.

JKU rebuild

It was a roll over with most if the damage at the front right corner were the windshield, right door, and roof meet. Along with rear inner axles being bent. I agree its a strange issue, I did check the the wiring visually and for connectivity, both wires got connectivity to the same pin on the plug that goes in to the ABS / ESP computer which seems strange to me.

JKU rebuild

Found this photo of the JL wiring diagram of the ABS system. Looks like each wire of the ABS sensor goes to a different pin on the computer. So if the JK is similar there might be a problem with my wires because I get continuity to the same pin from both wires. If anyone has ideas or experience on locating electrical shorts in jeeps that would be really appreciated and thanks for the feedback so far.

jedg

This place may have the pin out for the plug you're working with. Just have to find it.

Mopar Connection Repair Kit

JKU rebuild

Thank you so much this is very useful, saved me having to buy the JK electrical diagram.

JKU rebuild

So I did some testing today using the pin outs from the website you gave me, I tested continuity and resistance from the wheel sensor to a inline connector (INLINE-CHASSIS/DASH 68429700AA) and from the inline connector to the ABS computer connector and I got little resistance (2 ohms) and good continuity for both wires. The only thing that I changed from the last time I measured the connection (when I was only getting one pins connection) was that spayed some QD electronic cleaner on the terminals of the ABS sensor and connector. So I decided to turn it on and take it for a test drive the ABS and traction control light were still on. As I backed out it performed as it should only after going forward for around 3 seconds did get one small jerk of it applying the brakes. After that it drove perfectly normal at a range of speeds, but I did notice something on that dash that I may not have payed attention to before is that after the one small jerk a few seconds after that the hill decent control light flashed a few times. I decided to experiment with this and turned off the jeep then stared it back up again then drove it forward. I did this process 4 times and every time after moving forward a bit there would be a small jerk and the hill decent light flashing a few times than drove normally after that. What that means and how it is related to the other lights I don't know but I think its a clue to something. The systems are probably connected some how sense hill decent probably uses wheel speed. Going to checkout the condition of the wheel speed sensor and maybe replace it if its cheap to see if it fixes the problem. Also during test drive notice the wheel would slightly favor the clockwise side when going straight only by about 5 degrees via a meter I had plugged into OBD/ll port anyone know if that enough to trip the ABS and traction control light?

jedg

I'm glad that was helpful for you. Yeah, I would replace the sensor.. that's a cheap item. I would also correct the steering wheel being off. That's easy to do, adjust your drag link. I doubt 5 degrees off would have an impact, but it won't hurt to put it centered.