Trans/speedometer

[mike brez]

I have a Allison 3060 my speedometer is off by about 10mph
Is there a sensor/module on the trans that controls the speedo?

[wa8yxm]

There is indeed a sensor however it ios a hall effect sensor and those are either dead on or dead period. No "10 mph off"

This feeds a computer.. the comptuer controls the speed indicator

You need a re-flash of the computer's program.. I'm not sure which shop you need.. There are multiple interfaced devices but I'd start with an Allison shop.. Talk to them (need not bring in teh RV on the first visit) and they will tell you if they can do it or if you need to go somewhere else... and likely where.

[dbarton291]

If the speedometer in this vehicle uses the speedo output from the Allison, which is commonly done, there is no calibration done in the TCM. You can't fix it with any kind of a reflash. It's a fixed output across all models. If the speedo is off, it's most likely in the speedo head itself. All this is assuming tire size and/or axle ratio have never been changed in the vehicle.

If the speedo is connected to an engine output, or a body control module or something else, I really can't say how those work. Those may have programmable options.

[nehog]

If this is important then one of these modules may (MAY) work for you. We used these in the Hummer H1 to calibrate the speedometer. If you get one from a junk yard, email or message me and I'll send you calibration instructions.

[grldst]

I had to replace a speedometer/odometer on a 1997 Monaco Signature once, and the speedometer had dip switches on the back of it that you would set accordingly so that it would read correctly.

Might be something worth checking out to see it that's the way yours is setup.