I just towed my 08' JK back from the RV dealership behind my motor home and noticed that I was registering miles on my trip meter and was suddenly getting 35 miles per gallon on the mileage meter.
I am not sure if it registered to the odometer as I did not check the overall mileage when I hooked up but I had checked the trip meter to see how far it was to the dealership. The gas mileage speaks for itself as I have never seen more than 19 mpg on the meter before.

I definitely had the transfer case in neutral and the auto gear shift in park and performed a test to make sure by putting the jeep in drive and tested for movement as the owners manual instructs.

Any ideas? It sure seams as though my transmission would have to turn to accomplish adding miles to the Jeep.

 

While I'm not 100 percent sure if what you experienced is true or should be happening, I do know that the speedometer "sending unit" is not in the tranny, but on the wheels. So it may be possible that the Jeep is registering miles while being towed.

 

what towbar system do you have

 

maybe you should pull the IOD fuse... I dont know if you need it to flat tow, for lights or something, but I would imagine puling the IOD fuse would disconnect the power to whatever is registering the mileage

 

You "know" incorrectly. It IS in the transmission.

 

Thats what I do

 

Well, I have towed my Jeep for over 5000 miles and it does NOT register the miles. On one trip to Colorado I did not pull the fuse. It still did not register the miles but did give me a very low battery when I got there. I towed it to Florida last year 1800 miles there and 1800 miles back and no miles added then either and had no battery problems with the fuse pulled.

If you are regestering miles then something is wrong!

Jeff

 

Found my solution
I had the key position in "ON" not "ACC" that caused the miles to rack up on the trip meter. "ON" must turn on the computer. It was nice to see 35 mpg on the dash, I should have taken a picture and told all of you I would sell you the secret.
I also learned on a different forum before I returned here, confirmed by others here on this thread, that you pull the IOD fuse to eliminate the power draw on the battery from the key in the ACC position. Long trip = dead jeep.

As a good friend tells me. You need to be slightly more intelligent than the equipment you are trying to operate!

 

Forgot to reply to a previous question.

I use a Roadmaster Falcon II with Roadmaster MX brackets and Cool Tech wiring harness. Great setup!

 

I was also under the impression from what I've been told that the speedometer uses the ABS sensors. I was told you can change gears without affecting the speedometer but if you change tire size the speedometer will be affected. I was told on older vehicles if you could match the gear ratio perfectly to tire size your speedometer would be correct but on the JK the tire size is the only thing that affects the speedometer and gear ratio has no affect what-so-ever.