What to use to calibrate speedometer and read RPM

[CTD12V]

I have a '98 12-valve. As such, the odometer/speedometer is electronic, based off the ABS sensor on the rear diff. I would like to recalibrate my speedometer, and I also want a tool to read my RPM, to double check my factory tach and idle speed for adjusting breakover on my throttle linkage.



Obviously, a DRB scan tool would accomplish this, but their cost is out of sight. What other tools would allow me to do these two functions? Is there some generic scan tool that I could rent from an auto parts store that would do this, or does it have to be Dodge specific?



Thanks,



CTD12V

 

[p-Bar]

Dodge is it unless you can find an independent with a DRB III. Should only cost you 80. 00 that seems to be the going rate. Not sure on the tach maybe the DRB III again.

 

[Bob4x4]

The factory tach is never spot on but does 50 rpm at idle make any difference?Not to me. You do not need a tach to set the idle speed where it runs the best. There is no adjustment to calibrate the Tach,although you can on a Caravan :-laf



Bob

 

[CTD12V]

I think I saw it mentioned somewhere that a Smarty programmer for 24-valves can calibrate the speedo? The speedometer part of the PCM shouldn't be any different for my '98 12-valve. Anybody know if Smarties can be shared among trucks, or are they VIN specific?

 

[EricBu12]

I got the Superlift Spedo calibrator which has 2 positions for 2 sets of tires if you use different ones for winter like I do.

Superlift Suspension Systems Superlift TruSpeed Speed Signal Calibrator (Engine Performance - Speed Calibrators) at Truck Hownd

 

[LKuilder]

I used the Superlift TruSpeed box in my 99 as well with good luck. Was very easy to install just tapping into two of the ABS sensor wires under the hood and supplying power to it. Plus, I also liked the fact that it had two different settings because I run two different sized tires as well. Just flip the switch when I change out tires and its all set. It says in the instructions to try and use a GPS to calibrate it exact but I had no access to one and I found using the method with mile markers on the highway to work pretty accurately for me.

 

[CTD12V]

Thanks for the suggestions, guys. I suppose if I ever get around to it, I'll just have the dealer recalibrate it for me. Unless anybody along the Front Range in Colorado happens to have a DRB tool they want to let me borrow for a half hour?

 

[dan_gilson]

I have a TrueSpeed. I got it from Rickson Truck tires. It works super. Using the mile markers on I-5 I got it to be within a 10th of a mile in 10 miles. It has a 15 turn pot which allow for pretty infinite adjustment. It was easy to install - tool about an hour. I recently had problems with the adjustor coming loose and getting in the way of the emergency brake. A couple of wire ties fixed that.

As for the Tach. Have you thought about getting a ODBII checker? The ones that plug into a lap top will give you real time data from the engine computer.

 

[CumminsPower98]

Add another Tru-speed for me. I love the switch since I also have two sets of tires, which are different sizes. It has worked great since '01.