So I had an ABS light going on and off on my 05 250, finally got it read, and the computer said right front speed sensor. I changed it and the light stayed on all the time then. I had somone plug it in and drive it and the left front sensor was reading nice and flat on the graph, while the right front was spiking all over the place. I then assumed I got a bad sensor. I changed it one more time and now the light still won't go off.
Now what?!

 

The codes triggering the ABS light have to be cleared by a dealer.

 

The dealer is the one that tried to clear them the first time and read the sensors on the graph. They also said that unhooking the battery will clear that code.

 

Yeah, that should work. You have to leave it disconnected for 10 mins or so to be sure.

 

I've done that. Now I'm trying to figure out what to look for next. The only thing I can think of is the wiring going to the sensor itself. If I had a corroding wire and moving it around broke the connection even more would it now stay on steady? How do I tell without changing wiring harnesses?

 

You really need to have the ABS codes read so that you know what is triggering that ABS light. Without knowing the source of the fault code, you are shooting in the dark with any problem-solving efforts.

Perhaps a local Autozone (or equivalent) could read the code for you.

Lou Braun

 

Autozone told me they can't read ABS codes, only engine codes. I don't want to have to go back to the dealer to have them read it again. They did it as a favor for me the last time and didn't charge me. I can't imagine they would do it again!

 

I got the code read and it's 1234. From what I understand, that means there is an open circuit. I traced the wiring up to the main harness at the top of the fender and nothing looks bad. Any ideas as to where to look to see if there is wiring problems?

 

The 1234 code means "speed wheel RF input signal missing". If you trace from the right front speed sensor, the wire goes behind the right front wheel-well to a connector. The connector is on the outside of the vehicle, behind the splash shield just about 8" behind the front right tire.

Disconnect, clean and lubricate that connector. With luck, the connection is corroded and the cleaning will fix you up.

You can check to see if the sensor is sending a signal to the connector by using a multimeter with a milliamp setting. Raise the right front wheel off the ground and spin the tire. You should see an output current from the sensor (10 milliamp or thereabouts). If there is an output, the sensor is receiving a signal from the tone ring in the hub assembly and the system is working OK.

If there is an output at the sensor's wiring, the problem might be caused by a poor connection to the ABS module under the hood. Check the connectors there for corrosion or damage.

Clear codes, and try again.

Lou Braun

 

Thanks for the advice Lou. I'll see what I can do in the next couple days. I'll let you know what happens.

 

Lou is a very infomative person!! and very correct... The dealer that gave you information would have found the problems if you had given them the chance

 

Is the sensor ring clean and undamaged? gregjo1948