Wheel Speed Sensor/Harness Issues - ABS/VSC TRAC/VSC OFF - 2001 LX470 (1 Viewer)

[JonathanSed]

Hello everyone, long time lurker, first time poster. I drive a 2001 LX470 with about 195k on the clock. Have 33s on her, but that's the only modification so far. Looking to get it running reliable for a while before I start doing fun mods.

I have the typical ABS/VSC TRAC/VSC OFF lights and I think I'm getting to the limit on what I can do alone to get rid of them. I've done some troubleshooting and a lot of research, but I'm wondering if anyone has any insight that may help me with my next steps and/or other ideas.

The problem initially started around the same time the sunroof seal leaked a little while back letting water into the cabin and I'm guessing other places where it's not welcome. I replaced the seal, but the warning lights are still on. The main symptom other than the warning lights is that occasionally, when going around a slow left-hand turn, the traction control will kick in, apply the brakes (with a harsh "grinding" noise and pulsation in the brake pedal), and kill the throttle. The green "active trac" light flashes, and I have to apply the brake to get it to stop and get the throttle to work again. Not ideal when there are other cars around…

I got TechStream up and running and read the following codes:

1. C0200 - Front Speed Sensor RH Circuit
2. C0205 - Front Speed Sensor LH Circuit
3. C1223 - ABS Control System Malfunction

Taking it for a test drive, everything seemed pretty normal except for the FR wheel speed sensor and the steering angle sensor. Here's a picture of what I'm seeing when driving.

Based on what is said in this forum, it sounds like the steering angle sensor stays at 1150 until reaching 28 mph. When I was driving around, the steering angle sensor started reading once I got above about 25 mph. Is this something the steering wheel sensor does every time you start the car or could this be indicative of an issue? During the drive, the front right wheel speed sensor never behaved for more than a couple seconds at a time.

I also followed the instructions found here to test the front wheel speed sensors and wiring harnesses. Here are my results

Right Hand Side:

1. Sensor resistance = no connection
2. Wiring harness connection
   
   • 2-GND = 10 Mohm
   • 1-GND = 5.7 kohm

Left Hand Side:

1. Sensor resistance = 1.03 kohm
2. Wiring harness connection
   
   • 2-GND = 5.7 kohm
   • 4-GND = 10 Mohm

I pulled the ABS ECU to look for signs of water intrusion, but I didn't really see anything. Messing around with control boards and wiring diagrams are a little above my current level of understanding, so I'm not really sure where to look or what to test. If anyone sees anything that looks off in the picture below, please let me know. Also, if anyone can tell me at which port the speed sensors plug into the ECU, or how to verify ECU health with a multimeter, that would be great. I tried to do a connectivity test between the FL speed sensor harness and the ECU plugs, but it was inconclusive (I think my multimeter lead was a bit too big to fit into the holes in the plugs and I was getting back cramps).

Based on the readings above and what I saw when driving with TechStream, I'm going to replace the FR wheel speed sensor. The manual doesn't mention what to do if you get low resistance on the wiring harness side though, so that's what I'm looking for help with. Does anyone have any tips on where to go from here? Also, if anyone has any other ideas, I'm all ears.

Thanks for your help!

 

[El Cid]

Interesting. I just fixed something similar and might be able to help. Let me get techstream up and see how it works. Since you’re in Houston, maybe I’ll DM some questions,

 

[JonathanSed]

Interesting. I just fixed something similar and might be able to help. Let me get techstream up and see how it works. Since you’re in Houston, maybe I’ll DM some questions,

I got the new wheel speed sensor installed last weekend, but hadn't gotten around to posting an update. All of the warning lights are gone and techstream is showing speed from each sensor. Glad to have this one behind us. Still not sure about the out of spec resistance readings on the wiring harness, but maybe they were reading off because of the fault in the system. I need to go in and re-measure now that everything is working and report back.

Also, this is the wheel speed sensor I ordered from Parts Geek. Hopefully it lasts a good while!

 

[El Cid]

I just ran codes, my light is on but I see no symptoms. So like yours, I think it’s just the seating of the harness.