I was wanting to make a variable gear change indicator unit for my MY00. I have a Defi HUD for MPH/RPM so could just link a transistor circuit on to the last LED and get that to flash at me but I wanted to make one with a variable resistor so I could choose when the big assed flashing LED comes on to tell me to change gear.

As the Defi HUD has only 4 connections to the back of the dash,

1. +12v
2. GND
3. MPH o/p
4. RPM o/p

I was going to link up to the same RPM connection as the Defi HUD but I don't know what the RPM output it. Is is a variable pulse signal or a linear voltage level.

If it is a pulse signal does anyone know the frequency per RPM value?
If it is a linear voltage level does anyone know the volts per RPM figure?
If it is neither can you please tell me what it is

I could just put a scope on the RPM connection but didn't really want to take apart the dash or HUD until needed really.

Any help/comments welcomed.

Thanks,

Nezz.

 

Nobody?

 

Speedometer pulse type 4 according to my hud

 

as to what it means

 

Yes selection 4 will give the display the RPM with the LED's at the bottom. What I want to know is what the frequency/amplitude etc of the pule is at set RPM's.

 

I don't know about the MY00, but on my MY95 the RPM signal is pulse width modulated with the interval between pulses halving as the engine speed doubles. I don't have the actual frequencies but have a PIC program that converts the signals into an RPM display.

From memory I think the signal is 12v p-p. I can measure it if you like and also get the frequencies at low RPM it that helps.

Matthew

 

I will put a scope on it at the weekend to see what it does.

 

Matthew - Can you mail me please I would like to discuss this futher.

 

Nezz - YHM