V88 Speedo Output Weirdness

[JAZ-013]

So I've just hooked up the dash Speedo on my '98 Supra to run off my V88 so that I can finally calibrate it.  It has been reading high for years.

However, I've got something weird going on. Soon as the car starts moving and the ECU has detected speed, the dash Speedo jumps to 20kph.  Once the actual speed catches up, the gauge is then absolutely spot on with the ECU through a full sweep. ECU reads speed under 20kph just fine so it's just the output/gauge.

Anyone know why it would work, but with the sudden 20kph jump? I'm using the IGN8 aux out if that has anything to do with it. 

Cheers.

[Adamw]

The minimum frequency the aux output can do is 10Hz.  So it will output 0Hz at no speed and 10Hz as soon as it starts moving.  This works fine with most speedos as 10Hz doesnt even register any speed but it sounds like 10Hz to yours means 20kmh.

[JAZ-013]

1 hour ago, Adamw said:

The minimum frequency the aux output can do is 10Hz.  So it will output 0Hz at no speed and 10Hz as soon as it starts moving.  This works fine with most speedos as 10Hz doesnt even register any speed but it sounds like 10Hz to yours means 20kmh.

Thanks Adam.  That makes sense. 

I have other options, but they mean I will have to live without the power-on sweep.   Worst case, I can just throw in an MXG when I win the lotto.