2019 RAM 1500 5.7 Larame Longhorn

[Trail Paver]

I just bought the truck, my speedometer reads 1 to 3 mph slow depending on the speed. Is the Alfaobd the right programer to use and what else do I need to buy to make it work with this truck?

 

[British Bulldog]

Tyre size? Has the previous owner swapped 20s to 18 or17?
I had a 2017 longhorn with 20” and when I put winter tyres on(17) it read low. I never bothered about it…..
I can’t answer the question, but maybe this is why it reads low

 

[crash68]

Is the Alfaobd the right programer to use and what else do I need to buy to make it work with this truck?

Yes, you'll also need a security gateway bypass cable, and preferably an OBDLink MX or MX+ Bluetooth dongle.
Read through at least the first post of the AlfaOBD thread: https://www.ramforum.com/threads/alfaobd.123982/

 

[Socalramfan]

Just as important…. What size tires ?

Wheels might have been changed, but it’s going to be the ‘Overall diameter‘ that will effect actual rotational speed.o

 

[flinkpoyd01]

My 2014 Longhorn analog speedo reads nearly 5 mph off at 70mph compared to the digital speedometer. After doing a ton of research, it seems like this is a common issue with trucks imported from Canada (like mine) as there is a common speedo discrepancy for some reason. I'm not about to replace the whole cluster and I doubt a tuner will adjust anything on the physical gauge cluster, so I just live with it. The odometer is based off the digital readings, anyway, so the issue is simply an aesthetic one, although it messes with my OCD at times!

 

[flinkpoyd01]

Should have mentioned, factory 20" wheels and tires.