Hello everyone,

I hoping that I may be able to get some insight into how our speedometer functions so that I can work on figuring out a problem I'm having. Last weekend my speedometer stopped working while I was on a short trip. It just died and gave no readings. Of course the check engine light came on to let me know the speedometer was not working. The next day I started on my way home and the speedometer popped back on and began working again. The light stayed on so I took it into the dealer the next day (Monday).

The dealer kept it a day to tell me that they could find nothing wrong with the sending unit, computer, or anything else and that it must have just been a fluke. They reset the check engine light and things went fine. Until...

Today, while on my home from another trip the speedometer again went out. This time it dropped to 0 MPH then bounced around before staying a 0. The check engine light has come back on.

Does anyone have any idea of what could be going on or even where the sending unit picks up its signal. Does it work off the tranny or rear diff? This is for a 2002 4x2. Thanks for any input you might have.

Joe

I remember reading about someone else who had a similar problem. I think the wire coming from the rear end was contacting something else. It was frayed, shorting out, etc. Hopefully somebody else remembers a little more.

Is the odometer still working? If not, your going to have some miles in the bank.

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- Burchie

The Speedo and Odo are linked.

The Speedo sensor works off of a magnetic sensor on the top of your rear diff pumpkin (center section). It senses the tone ring wrapped around your gear carrier inside the pumpkin.

It is possible that either as skyjump said, it could be a worn or shorting cable, or it could be your sending unit od the diff could have gotten fouled or popped off or loose. Worst case scenario the toner ring slipped on your carrier, but then you would be hearing noises from the rear end.

Dealers will not spend time to try to reproduce things, but if I am not mistaken, they can look in the computer for prior codes even if the check engine light has turned itself off. Older Chrysler computers used to store the last 50 codes recieved unless the system was reset. My old minivan did that (94 caravan).

Hope this helps

Ted

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I'm baaaaccckkk...
LOST Member 10
If you can read this you don't need glasses, go Wheel your Jeep!

Thanks USAFCOP,

That definitly helps. I was outside a bit ago to take a look under the Jeep. Found fresh gear oil all over the fromt of the rear diff. Looks like that must be where the problem is.

Joe

My truck did the same thing, I checked the engine codes by cycling the key back and forth about 5 times, and looked the code up on obdii.com... turned out to be a speed sensor. Took my libby to the dealer and told them what was wrong... couple hours later.. fixed.. good as new....

IELiberty.

I had the same issue about a month ago. If I remember correctly there is a plastic clip that holds the sensor in place, mine was broken and caused the speedometer to bounce around.

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08 Jeep Wrangler Unlimited Rubicon
Rescue Green
Teraflex 2.5in
Huskey Liners
Sill Guards
Grab Handles
Neoprene Grab Bar / Handle Wraps

Well Skyjump was the winner in this one. The parking brake cable had come loose and contacted the speedo, shorting it out. Dealer retied the parking brake and then replaced the end of the speedometer cable.

The gear oil was from the pinion seal leaking like crazy.

Joe

Same happen to mine, so all you boys and girls check your wiring in the back by the break cables!

Al

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One Ruby, One Grand Cherokee, One YJ, One disassembled CJ, one Chevy Mason dump, one hotrod IH Pick-up, couple of antique tractors.
Former owner of a 5.5 inch lifted KJ

Thanks for the update. I'm going to check mine as soon as I get home!

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Jeremy - Aurora, CO
L.O.S.T. #0

Future:
2016 Hydro Blue JK Unlimited Rubicon Hard Rock

Previous:
2012 Flame Red JK Unlimited Rubicon - Sold!
2012 Flame Red JK Unlimited Rubicon - Dealer buyback
2003 Silver KJ Freedom 4x4 - Sold!
32s, Frankenlift, BBars, onboard air, dirt.
KJ EVIC Install

Looks like everyone effected by this issue needs to file a Complaint with the NTHSA to issue a TSB or Recall.

Click on the link below to do so.

http://www-odi.nhtsa.dot.gov/ivoq/index.cfm

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2012 Liberty Latitude Edition,
Brilliant Black Pearl, Moonroof.

2013 Wrangler Sport

My indication jumped around for a while then went out completely. I checked all the connections on tranny sensors today, even pulled some kind of speed sensor near the back of it. Checked it and found it would generate a pulse so I thought I had found the speed sensor. Glad I checked the forum because I just went out and looked on the rear diff and sure as snot my wiring is rubbed into by the brake cable. Thanks for the info!