how do i adjust speedometer??

slice07 · 01-20-2010, 09:40 AM

i went to the dealership yesterday to order some parts and i asked em how much they charged to adjust my speedometer b/c i got bigger tires. they said they don't at all b/c it's all electronical now and they don't fool with it. i even asked if he knew anybody who did he said no....... so really there's nothing we can do?

sleepertrk · 01-20-2010, 09:47 AM

Quote:

Originally Posted by slice07

i went to the dealership yesterday to order some parts and i asked em how much they charged to adjust my speedometer b/c i got bigger tires. they said they don't at all b/c it's all electronical now and they don't fool with it. i even asked if he knew anybody who did he said no....... so really there's nothing we can do?

1) How far off is your speedo?
2) Why is your speedo off?
3) Hypertech makes a speedometer calibrator.
4) If its not off by much, don't waste your money its not cheap.

bestatchess · 01-20-2010, 10:05 AM

"Hypertech's In-Line Speedometer Calibrator Module is an in-line module to correct the speedometer and odometer readings for unlimited tires sizes and/or rear gear ratios. This module is perfect for vehicles with computers that dont allow for tire size and/or rear gear ratio correction or want to re-calibrate for tire sizes and/or rear gear ratios outside the range of programmers.

Using the USB cable, connect the In-Line Speedometer Calibrator Module to your PC and enter the new tire height and/or rear gear ratio. There are no limitations to tire height or rear gear ratios. Next, disconnect the factory connector to the instrument cluster (behind the dash), snap in the Speedometer Calibrator Module, reconnect the cluster and you're done! In a matter of minutes, you can accurately correct your speedometer and odometer readings (as required by law)."

The part about disconnecting stuff behind the dash sounds like a PITA.

WFO (apparently now out of business) did a SAS using custom tone rings at each wheel and got everything working, but that is expensive and also a PITA.

"We fired up the truck and backed it out of the shop. After driving up and down the street, we realized we had a problem. The speedometer did not work. Due to this problem, the motor would go into a limp mode after driving a small distance. It would stay running, but would lose all power. It would take a few seconds to kick back in. We were prepared to see the anti-lock brake light, and the 4x4 light, but not this. While taking out the original axles, we did notice that there were 4 separate speed sensors; one at each wheel. We also noticed that there was a speed sensor in the tail shaft of the transmission. At that time, we did some research on the internet. We also talked to a few Nissan techs. Everyone came to the same conclusion. The wheel sensors were supposed to be for the brakes and the tail shaft sensor was supposed to be for the speedometer. I guess we concluded wrong. With such new technology, nobody really knew how it worked.

After pondering the problem for a while, we decided the only way to fix the problem was to put speed sensors back on all 4 tires. Not only would this fix the speedo problem, but the anti-lock brakes would also function properly again. The truck would be back to its exact stock configuration. It all sounded easy in theory, but we didn't have the slightest idea how to do it.

We started by examining the stock toner rings. We now knew that the speedometer read from these rings, so we started doing some math. We calculated the % change in the tire size from 33" to 40". We designed our new toner ring with this % change incorporated into it. This would allow the speedometer to show the correct speed. The gear ration did not matter, due to the fact that the sensors measured actual tire rotation. The new rings were drawn on the computer, and custom cut from 3/8" steel. Once we had the rings in our hands, they were mounted on the 4 wheel hubs, using the factory Nissan speed sensor wiring.

To our delight, not only did the speedometer work, but all of the lights on the dash went off. We drove the truck down to the dealer to have them search for any bad codes. Once the old ones were cleared, no new codes popped up. The wiring was completely back to its stock configuration. Not to mention, the speedometer was almost right on!"

slice07 · 01-20-2010, 11:10 AM

i have 35'' tires now so it's only off about 3 mph. but in the next monthy after i get my income tax i'm goin to upgrade to 37 and new gears. i have no idea how much it'll b off then...

sleepertrk · 01-20-2010, 11:15 AM

Sounds like for now you should just leave it alone. When you get your larger tires and gears then you probably ought to buy the Hypertech calibrator unless you feel skilled enough to do the wheel ring conversion.

PRJ · 01-20-2010, 11:35 AM

Get a hold of GPS unit and take a ride. It will tell you how much it is off.

Pops · 01-20-2010, 11:36 AM

Quote:

Originally Posted by bestatchess

... The part about disconnecting stuff behind the dash sounds like a PITA. ...

From reading posts from the guys who've installed the custom gauge sets or done a cluster swap, they said it's really not that bad. IIRC, figuring it out is a little challenging but once you know it, it's not bad, from my understanding.

As for the speedo, only a special lockdown dept at NissanUSA can calibrate the feed for it. They have it all under wraps to supposedly protect against odometer fraud. IMO, they never had it right anyway. My speedo is more accurate now compared to the GPS than it was before I put 33's on. Think about how many more miles rack up quicker and additional service fees paid when on the OEM 32's.

The only way to get it to read different is to plug something in between the feed and the guage, which sounds like the route Hypertech decided on.