I was coming back from a trip and next thing I know my speedo is bouncing all over the place. It wouldn’t keep cruise on. I replaced the Ford VSS with another Ford VSS sensor and it still was doing it. Enough that eventually it put my E4OD in a limp home mode.

I suspect the problem is damage to the tone ring. Would this cause the speedo jumping in the video clip? Worst part is, I paid good money to have the rear end done 2 or 3 years ago and have only put minimal miles on. I don’t want to pop the rear diff cover off just yet in case the shop try’s to say it was tampered with so the photos are through the VSS hole.

 

Yes it will. It looks similar to what happened to my brothers truck a couple years ago. Ended up being a broken piece of ring gear that floated around and damaged the tone ring. The only sign of problems was the speedo. We ended up replacing the tone ring with a spare and it was fine. He didn’t do anything about the ring gear and it drove just fine.

good luck. I hope the chunk isn’t junked up

 

I hope the shop will honor it as I just found my receipt and I had the rear end fully rebuilt with a TruTrac carrier installed on 12/1/17 and have only put 10,375 miles on since.

 

I hope they honor it... We've talked about it before but that shop is crooked as a Mesquite tree so I wouldn't hold my breath

 

I've got it scheduled to go in a Wednesday. Hopefully they cover it. The owner actually sounded a bit surprised when I spoke to him and asked me to email him the photos I took. I'm curious as to what let loose. I didn't hear any odd noises or grinding prior to or after the speedo started going nuts.

 

Update, shop said rear ended looked fine and tone ring had minimal markings. They filled it up and didn’t charge me anything which is good.

I replaced the tone ring myself and took a look at the carrier and bearings and all looks good. The speedo stopped the erratic swinging but was still slightly unstable. I then replaced the PSOM with an eBay one and it works great now. I even rolled back 20k miles!

 

Another update. Took her up to 90 mph(I rarely do because of 4:10’s) and at about 86 mph the speedo jumped down by about 10mph but no other issues. I can live with that. I think I’m going to rerun wire from the VSS TO PSOM just to eliminate any possible shorts or grounding issues. I have a new VSS pigtail on the way too.

 

Awesome man! I'm glad that shop didn't charge you anything.

Come down and see me sometime, maybe during the winter lol

 

I was surprised they didn't charge me. They even added new fluid and changed the weight because they said Eaton put out an update for the TrueTrac to run 85w140. Stuff is thick like molasses!

Once of these winters I'll try and make it down your way, thanks!

 

Sort of unrelated but at the same time relevant:

Will a PSOM from a gasoline pickup work with a diesel cluster?

 

Great question, mine is acting up between 40-65 MPH and theres alot of gassers in the JY.

 

I don't know why they would be different but I have seen much dumber things.

 

Any 92 to 96 will work no matter the engine from what I’ve found. I got mine off eBay for $50 and it had no description of the vehicle it came off. Old on the left and eBay on the right.

 

Good to know. My 265K 7.3 is about to be 112K.

I won't ever sell it so no worries. A working speedometer and cruise control are important!

 

For the bouncing speedometer, you can try unpluging the RABS module behind the glovebox. That's what cured mine. Apparently if you have a weak VSS signal this will take some of the load off. Of course you won't have rear anti-lock brakes but your not missing much.