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GPS Speed Sensor setup


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Hope you can assist.

I am trying to setup a lockout for Transbrake based on "any speed" to avoid accidental engagement.

Vehicle has Autometer speedo with GPS sensor.

Hoping you can suggest a method:

1.Use the sensor to provide speed input to the ecu (thunder)

2. Provide output for the speedo

3. Lockout the transbrake switch function if any speed detected


Appreciate any thoughts


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  1. You can connect the speedo to the ECU via CAN.  Some pics below from one I have set up for someone else in the past.  Make sure when you choose the "LF Wheel" parameter when adding it to the stream that you have the receive filter turned on.
  2. Not sure what you mean here.
  3. Assuming the transbrake is controlled by the ECU then put LF wheelspeed<10kmh as one of the conditions on the transbrake aux output.




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Appreciate your assistance - hope i can request a bit more.

I have nil experience/knowledge of wiring CAN systems and have no idea what to do with physical wiring - can you advise?

I have a single signal wire that goes from the Autometer GPS Speedo interface to the speedometer - this interface module instructions say it is calibrated for 16,000ppm  and outputs a 12v square wave

Appreciate any assistance you can offer.



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It sounds like the output is very similar to what you'd see from a traditional gearbox sensor. connect it to any free DI, the configure the DI as LR wheel speed frequency. Try with pullup Off for a start, and if you see 0 all the time, turn it on a re-test. Then set the calibration value to about 500 - I think that will roughly match a 16000ppm output. 


Then set up logging, go for a drive at 2x constant speeds (50kph & 100kph is usually good), hold the speedo at this speed for say 10 seconds each. If you have a friend, update the calibration value until the ECU speed matches. If you dont, look at the log after and calculate the % difference between the ECU speed and the GPS speed, and adjust calibration value by this %.

[edit], at 16000 ppm you will need to connect to one of the higher frequency DI's. Officially the lower ones max out at 500Hz, which will be about 200kph for you. Depending on a few other things, you may have it work above this frequency, but given you have a thunder, just use a high frequnecy input.

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