ABS light on Speedometer erratic | Ford Explorer Forums - Serious Explorations

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ABS light on Speedometer erratic

mersberg

Member
Joined
June 25, 2006
Messages
34
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0
City, State
Honolulu,Hi
Year, Model & Trim Level
00 EB 4WD
Been having the ABS light come on and the speedometer will go erratic from 0 to 80-90 mph. When I'm going about 40-50 mph and the speedo hits 80-90 the truck will slow down and pulse till the speedo hits the 0 then accelerates normally until the speedo swings back up to 80-90 mph but the rhthym is 0-80-0-80-0no intervals just up-down-up-down till I slow to a stop. The RPM stays constant . Thanks.
 



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Well, that MAY fix the problem BB. Here's the deal with around that year car. The VSS signal is actually sent to the ABS module where it is distributed to the rest of the car. So if you are having multiple problems, then your problem can be from the source or the ABS module itself. I found out something very interesting one day. I had one with an ABS light on. Everything else on the car using a VSS signal was just fine. When I pulled the ABS codes, I had TWO sensors that were totally dead. My scan tool would actually read each individual sensor. I then checked each sensor with my meter and confirmed the only sensor I had working was the LF. Yet, my VSS signal was perfect. Speedo, cruise, trans, all of it worked fine. After reading the manual, it appears the ABS module will take any of the three sensors available and use it for the VSS signal. Makes sense. So if the 2000 is that way, then some work needs to be done to find where the signal is being degraded. It's possible it could even be the ABS module. This needs some "detective" work...

Now, just to throw a wrench in the pile, somewhere around 2000 or 2001, Ford changed the way the VSS is processed and I believe it's all handled by the PCM. That design might very well only use the rear sensor.
 












Well, if that happens, changing all the sensors in the world won't help and he will have other much more serious issues then this if it's a 4WD. It would be interesting to see how the ABS module handled different speeds from different sensors. Since it can operate with just one working, I would bet it would use just one input and ignore the rest except to set the ABS code.
 






I have had a similar experience.

1999 Explorer 4L SOHC AWD

When I reach between 60 and 70 MPH, my speedometer occilates, the ABS light comes on and then it all works normally. Once the ABS light is on, I no longer experience speedometer occilation in that speed regime. I am planning to replace the rear speed sensor, but I wonder why it would only happen once, if it was a continuous bad signal? My guess is a potential bad ground to 4WABS module that the light is providing alternate ground.

Any suggestions? Thanks for any help!

Update: replaced rear sensor, no joy. Still have the same issue! Help!

Update: Problem solved.

The problem was the rear differential. Eventually, the light came on when the vehicle started moving and it later came on when it was started. This was due to the bearing in the differential being worn and sufficient play in it to damage the replaced sensor. Had the rear end rebuilt and all is well. Thanks to all that helped.
 






What I did was on my message center there was a wire that heated up and it was the ground signal that was sent to the computer and when it heated up it lost its ground and my instruments when hay wire. You might want to try that if you have a message center like me.
http://www.explorerforum.com/forums/showthread.php?t=176664&page=2
I just ran a good grounded wire to a grounded portion of the message center circuit board and my problems went away.
 






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