Ok, 2001 Lexus GS430
My speedometer and ODO stopped working all of a sudden, and the ABS, VSC, and traction control lights come on on dash, codes said speed sensor, I've replaced all 4 at the tires and the back tranny one. After I clear the codes the speedo and odo work... UNTIL I hit about 65 and speedo drops out and the ABS, VSC, and traction control lights come back on. my cruise control is NOT effected at all though and works fine with the dash lights on. Don't know what to try next but here's a few things I might? try next or ask for any insight from you all. 1. there's an ABS motor relay in the blinker stalk on the steering column, could that be the cause. 2. there are 3 big relays in a box under the hood, the ABS motor, Trac motor, and ABS Sol relay's, could that be causing the issue, 3. the throttle position sensors, there are 2 I see, and could one of those be the culprit?? and by the way, when the speedo stops, my onboard m.p.g. screen in the Nav. system stops reading as well. Sorry for the long post, but I'm running outta fix options, any help would be greatly appreciated. Car runs great in all other ways speedo working or not.

 

Still hoping for some suggestions :-)

 

Well, I dont know if this will help or not. There is a vehicle speed sensor that goes from/to the Engine Control Module. But the manual is vague to say the least. It just says "The vehicle speed sensor (electronically controlled transmission) detects the vehicle speed and inputs a control signal to Terminal SP2+ of the engine control module ". Let me dig around some more. I am curious.

Paul

 

Check this and its wiring to/from the ecm.



Sorry for the sideways image. Good luck.

Paul

 

Thank you! I will check that out later today, that's the one on the tranny I changed, I'll have to get it out and test the connecter and wire going to the ecm.

 

Still haven't been able to get it up on a lift, so haven't been able to check the wire, I will update this when I can, T.Y.

 

I have the same issue on my 98 GS4.
DId you ever find a solution?

 

The speedometer doesn’t use the wheel speed sensors for anything, the wheel speed sensors are strictly for the ABS and VSC. The speedometer takes a reading from a small gear that is in the transmission tail shaft. Then it sends an electric signal to the ECU which sends a signal to the instrument cluster. The ABS uses the wheel speed sensors and a yaw sensor that is mounted under the glove box to determine how to use to use the brakes to keep the car going the direction the steering wheel is pointing. So your problem is most likely that gear in the tailshaft or the wiring. I would start by doing a visual inspection for any damage or anything that has an obvious problem. If everything looks you need to remove the gear mechanism and inspect it, it can also be tested by hooking up a multi meter to it and then spinning it with a power drill and confirming that it’s putting a signal. There is a testing procedure in the repair manual. I don’t have access to one right now or I would Share it with you, but you can buy one on eBay or sign up for 30 days of access to one online.