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Old Jun 13, 2012 | 11:59 AM
  #1  
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Speedo issue

My speedo bounce while I drive and I am not sure what to check next. I replaced the sensor at the rear axle and that didn't fix it. The old sensor had a groove worn in the center of it from rubbing on something, the new one is not showing any damage after driving it but my speedo still is not functioning properly. Could an issue with the wiring or pigtail to the sensor cause the issue? Is there a way to check the wiring? Could this affect my cruise control? Thanks guys.

-Joseph
 
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Old Jun 13, 2012 | 12:31 PM
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Issues with the wiring or pigtail will definitely cause the speedometer to bounce. Inspect the pigtail closely for chaffed wires and exposed conductors.

Yes, most definitely this could cause issues with your cruise control.

If there was a groove worn in the old sensor, I am going to wager a guess that the tone ring is broken. You will have to pull the rear diff cover and take a look see, but that's my guess. Visually inspect the wiring first though.
 
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Old Jun 13, 2012 | 11:46 PM
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Yeah, the tone ring is my concern. I have never had an axle apart that has a tone ring in it, is it safe to assume the carrier has to be pulled to replace it or is it even replacable? I will also check the wires in the morning.

-Joseph
 
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Old Jun 14, 2012 | 06:15 AM
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You can replace the tone ring, but you will have to pull the carrier to do it. It's not really that bad a job...
 
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Old Jun 14, 2012 | 08:01 AM
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Inspect/clean the tone ring first. If there's crud on the reluctor teeth, or between them, it'll throw off the VSS.
 
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Old Jun 18, 2012 | 11:24 AM
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PSOM. Search is your friend.
 
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Old Jun 18, 2012 | 11:52 AM
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Pull the vss out and clean the mounting surface. If it has rust built up on it it can cause the air gap between the vss and tone ring to be much and can cause speedo issues
 
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Old Oct 2, 2012 | 12:01 AM
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So I finally got around to tinkering with this issue and pulled the cover on the rear diff. What the #$!?!%$?, the tone ring is..... tack welded in multiple places to the carrier because it was cracked in at least one place that I can see. What are my options? I figure I could drop the carrier, grind the weld off and then replace the tone ring? New carrier? What would happen if I ran with the VSS unplugged?

My speedo bounces, my tranny shifts funny with out throwing a code or blinking the OD off light, and I get an intermittent ABS light. Oh yeah, no cruise control either. I can live with all of it accept the tranny issue which I don't know for sure is related to this. Sometimes it will shift very firm, sometimes it shifts quick between gears, and sometimes it is long winded between shifts.

Do you think there would be any chance that I could clean up the area around the hole where the VSS sits and maybe seat it better and have it work? I know that these sensors are supposed to be located within .001's of an inch, is there any wiggle room in the tolerance of the distance between the sensor and the ring?

What do you guys think? Thanks.

-Joseph
 
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Old Oct 2, 2012 | 12:55 AM
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Tranny issue is probably also attributable to the tone ring / VSS problem. If you try to run the truck without the VSS, the auto tranny will not shift right at all. Kinda makes sense that it's not throwing a CEL; the PCM literally thinks you're speeding up and slowing down every time there's an irregularity in the tone right signal to the VSS, so it sees that as "normal".

Dunno about the plan to clean it up; just guessing, but I would think if the tone ring is cracked, it has to be replaced.
 
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Old Oct 2, 2012 | 07:00 AM
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I think if it were me, I would try dropping the carrier, cleaning things up and replacing the tone ring. I would carefully grind the welds off, then replace the tone ring. I don't know maybe you could take it somewhere to a machine shop and have them cut the welds off with a lathe, that way there would be less chance that the carrier would be too small to hold the tone ring on there right. I wonder whether some Loctite would help to hold the new tone ring in place?
 
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Old Oct 2, 2012 | 07:59 AM
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So does the tone ring just press on to the carrier? I will probably go the route of cutting, grinding, and replacing. Is there anything I need to know about removing the carrier? Looks pretty straight forward. Unbolt and remove shafts, remove the caps on each side of the carrier, pull out? I have been into a c-clip axle before but not a full floater so I am not sure if anything needs to be done with the spider gears? Thanks.

-Joseph
 
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Old Oct 2, 2012 | 08:22 AM
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The tone ring just presses on, IIRC. Just be sure you keep the shims straight as to which side they go on.
 
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Old Oct 2, 2012 | 10:08 AM
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Here's some useful links Dutch...

https://www.ford-trucks.com/forums/1...with-pics.html

http://www.eaton.com/ecm/groups/publ.../ct_128303.pdf
 
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Old Oct 2, 2012 | 10:11 AM
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BTW, keep the bearing caps and shims in the order they came out.
 
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Old Oct 2, 2012 | 10:54 AM
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where are you located? Might be easier to replace the axle. I have found some axles for $100. Or maybe someone around you has a spare.

richard
 
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