bennehboy / arduinospeedocorrection

Arduino based speedo correction for ABS vehicles, with optional 2nd channel final drive correction

ArduinoSpeedoCorrection

Arduino based speedo correction for ABS vehicles, with optional 2nd channel final drive correction

Based upon the 1986 944 Turbo Speedometer Calibrator written by Tom M'Guinness

http://members.rennlist.com/tom86951/Speedometer%20Calibrator%20Page1.html

Code kindly used here with consent from Tom.

Goal

This project aims to provide a cheap means to transform PWM speedo signals (VSS) from Land Rover TD5 SLABS units so that:

1. Vehicles with larger than standard tyres can have a corrected speedo which does not under report
2. Vehicles which have significantly altered drivetrain ratios can still utilise cruise control. (The factory ECU prevents cruise control from working if a calculated vehicle speed, based upon crank, speed differs from the VSS by ~ > 10%.

Status

In development, research of VSS waveform underway.

License

The source code of this project are released under "THE BEER-WARE" license.

I would, however, consider it a great courtesy if you could email me and tell me about your project and how this code was used, just for my own continued personal gratification :)

Contribution

Contributions in all forms (including documentation) are welcomed. If you would like to contribute to this project, then just fork it in github and send a pull request.

arduinospeedocorrection's Issues

1Hz minium pulse is wrong, it should be 2Hz

Per RAVE

On vehicles with manual transmission, the SLABS signal is checked against a threshold value stored in ECM memory.
If other engine parameters indicate the engine is at high load and the VSS is below the threshold, a fault condition is
registered in the diagnostic memory.
The vehicle speed signal generated by the SLABS ECU is in the form of a pulse width modulated signal (PWM).
Pulses are generated at 8000 per mile, and the frequency of the signal changes in accordance with road speed. At
zero road speed the ECU outputs a reference signal at a frequency of 2Hz for diagnostic purposes.

Understand this is probably dead, not expecting an update just dumping it here for anyone that finds this from searching.