All right, my speedo sits pegged at 120, then as I increase speed it moves backwards to 80 and stays there. What the heck is up? I replaced the speed sensor in the diff and the two in the tranny, but that did not fix it. WHere do I look next?

I have a 2001 SLT 4WD 4.7L. Everything works like a dream except that damn speedo!

 

take the plastic lens off the instrument cluster and try flipping the speedo needle back around to 0 when the truck is off, see if that fixes it (idk how it for flipped to 120 in the first place, but i have heard of this fixing the issue)

 

Try running the needle re-calibration program.

IndyDurango

 

Yup,

Flip it back as a freak thing could have happened. If it goes back over you could try resetting the cluster. If that doesn't work then you will need to get a new cluster from a junk yard.

 

From what I understand (thanks to you) that resetting the cluster doesn't re-calibrate anything, it only ensures that cluster is reading properly or that the tech can place the neelels in the correct position so that you technically "calibrate" it to the inputs, but more importantly ensure it's reading in the correct position. To do this the tech pulls the needles and resets the cluster and places the needles in the correct position as indicated by the reset formation.

 

It is going to tell you in the travel is correct for each needle. Instant feedback towards determining the need to just scrap it and get a new cluster or not.

See?



IndyD

 

Pardon my ignorance but how is this done?

 

Ok, I ran the instrument cluster self test. It resulted in all the gauges worked fine except the speedo. It rose from 120 to 80 and rested back to 120. Is this a bad cluster issue or a bad circuit somewhere?

 

I'd vote on bad cluster.

 

id still try flipping the needle back over by hand before buying a new cluster, if it lasts, great, if not you didnt spend any money on it.