Truck Speedometer Fix via GPS to CAN and Raspberry Pi

Fixing Truck Speedometer via GPS-to-CAN module + Raspberry Pi

Case Studies / Private


In this case study Philip uses the CANmod.gps as a solution for re-enabling a truck's speedometer after an electrification process.

What problem did you solve?

In 2010 I converted an old Dodge Dakota truck to all-electric power. That process involved removing the engine, and thus also the engine computer. In this vehicle the engine computer also provided the signal to the speedometer, so that left the speedometer inoperative.

How did you solve it?

I actually had other solutions to solve this problem before recently discovering the CANmod.gps. Back when I converted the vehicle I had never even heard of CAN bus. The most recent solution involved a Raspberry Pi that would send an appropriate signal to the speedometer. The Pi would know the speed of the vehicle via a USB-attached GPS receiver. The problem with that solution was a lack of reliability in the consumer-grade USB GPS units I tried.

When I installed a new CAN-enabled battery charger and battery management system within the past couple of years, I started exploring additional possibilities with CAN bus. That's when I discovered devices such as the CANmod.gps, which would simply populate the CAN bus with GPS-derived data. Since I already had a Raspberry Pi monitoring battery charging & health via the CAN bus, it was a simple addition to include the CANmod.gps in the CAN bus of the truck. So now the Raspberry Pi simply reads speed data from the CANmod.gps via the CAN bus and can then thus provide the appropriate signal to the vehicle speedometer.

GPS to CAN Speed Signal Retrofit

"The CANmod.gps is exactly what I was looking for: A simple, compact device that would measure GPS data and output this via CAN bus"

GPS to CAN retrofit speedometer

What benefit has this led to?

This is a personal project - but it has provided benefit to me in that I now have dependable, reliable speed and position information in the truck.

Why did you choose the CANmod.gps?

I did look at similar products from other companies; frankly I chose CANmod because it was the most economical choice. I nearly purchased a competitor's product due to its higher GPS refresh rate (5 Hz), but decided it was not worth the extra cost and that I could live with the 1 Hz refresh rate that CANmod.gps provides (so, hint-hint - an option for CANmod.gps to have a higher refresh rate would be awesome!)

   — Philip Rash

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