I have recently been looking for a speedo converter for my J-spec TT6 (1993), as it's currently reading km/h.
I've not had a Supra long, but as far as I can tell from reading articles on the net, the speed signal is electronic.
If this is the case, does anyone know what type of signal it is? Is it pulsed or variable voltage, and if it's pulsed would it be width modulation or frequency modulation, as the cars speed changes?
I was thinking it would be pretty simple and cheap to build a converter using a PIC microprocessor. It's just basic math to convert from kph to mph and alter the speedo signal before it reaches the dial. This got me thinking it would also mean that it would be easy to make custom dash intruments. A Digital speedo displaying numbers could be made for just a few quid, and LED rev counters with shift light etc...
The speedo converters I've seen start at about £80, or there's the ebay ones for around £25, but are they reliable?
I reckon there can't be much more than £5 worth of parts in any speedo converter.
Can anyone enlighten me on the signal types, or do I need to go for a drive with my oscilloscope in the passenger seat and the dash hanging off ?