2nd Gen Non-Engine/Transmission Directions for Speedometer Correction for Different Tire Sizes

[DDaubenspeck]

Attached is a "How-To" document I created that explains the process of using the Chrysler DRBIII programming tool to correct the factory speedometer for different tire size for a 98. 5-02 Dodge Truck. Screens in the DRBIII make me think this proceedure will work for 94-06 trucks as well.



The pictures in this PDF document are not very good, because of the file size limitation of this forum. The text descriptions should make up for the low resolution pictures.



I have a larger size version with color higher resolution pictures so that it's easier to see the DRBIII screen shots - I'll see if I can get it hosted somewhere or if the TDR webmaster will make an exception.



This article was created only because A) I found a very nice guy with a DRBIII that loaned it to me, and B) my father attempted to get this fixed at his friendly Dodge dealer that sold him his truck and does some of the maintenance on it - and they told him, “You can't adjust that on your truck. ” I knew from reading the TDR website and magazine that this function is adjustable in the electronics, and that the dealer's techs or service adviser was either obstinate, ignorant, or too scared to try this. So, I had to become, as read many times in the TDR, “my own warranty & repair station. ”



I realize the DRBIII is hard to come by, but they are out there. If you want this done to your truck, maybe printing this article out, determining your tire Revs/Mile on your own, and then going to the dealership may 'git 'er done' for you.



* * *

This link should allow you access to a high-resolution version of the document prepared by Darren Daubenspeck. This is a 3. 8 Meg file.



<a href="https://www.turbodieselregister.com/Issues/Web_Tip_DodgeSpeedometerCorr.pdf" target="_blank">Click here to download. </a>



Thank you, Darren.

 

[RHestand]

Hopefully someone that knows will chime in here.

I'm very curious to know if this will work on a 2nd gen. 12V.

From all I've read previously, speedo. corrections had to be done mechanically?

Ray

 

[fox]

The dealers can adjust speedo for tire sizes. Some don't think so, or can't experiment to learn.

But, if you have a friend with a Smarty, it is very easy!!!!

 

[JLandry]

DDaubenspeck,

Excellent article. Thanks for taking the time to document what you did.

With your permission I'd like to post this on the Yahoo DRBIII user group:

DRBIII User Group on Yahoo

HyperTech programmers can also adjust the controller for speedometer errors.

Best regards,

John L.

 

[drag racer]

DDaubenspeck,
HyperTech programmers can also adjust the controller for speedometer errors.

Yes, works great and not terribly expensive. Beware though - for my year (1999) their unit only works with Kelsey-Hayes ABS systems. Apparantly there was another supplier, Bosch I think. Not sure about other years.

 

[CTD12V]

Hopefully someone that knows will chime in here.

I'm very curious to know if this will work on a 2nd gen. 12V.

From all I've read previously, speedo. corrections had to be done mechanically?

Ray

This proceedure will not work on a 12V older than 1998. In 1998 Dodge changed from taking a speedometer reading off a gear in the transmission tailhousing (or the transfer case on 4x4s, I believe) to a signal from the ABS tone ring in the rear differential. So the 1998 trucks with 12-valve engines will have a speedo signal that can be calibrated in the PCM via a DRBII tool, but anything older than that has to have a small gear changed out in the transmission/transfer case to correct the speedo/odo reading.



Now, the question is . . . How do we get a hold of a DRB scan tool without paying an arm and a leg!



CTD12V

 

[PRohr]

I have a hypertech programmer for my wife's Durango and I can DL tunes for different trucks and the '98 24v truck is on there. Can I plug that into the port on my 12V truck and adjust the speedo? Would I need to DL the 24V trucks program or will the '99 Durango's program work? I suppose I could plug it in and see but I would hate to ruin something on my truck or the programmer.

 

[Beast2B]

one at a time....

The dealers can adjust speedo for tire sizes. Some don't think so, or can't experiment to learn.

But, if you have a friend with a Smarty, it is very easy!!!!

The Smarty speedo correction is only available when the Smarty is VIN locked to a truck, so you can only adjust one truck at a time.

Also, the speedo accuracy is mediocre at best. Using a GPS as a reference I had to decide if I wanted the speedo accurate at lower speeds (up to ~35 mph) or higher speeds. I chose to be closest at 65 mph for highway speeds. It must be a digital-to-analog issue for the gauge because the odometer stays nearly identical cruising at either speed range!