Hi everyone i have been using CL for about a year but only just joined as i have q specific query,
i am looking for pin outs from the tach indicator ring light so i can use this wire as a signal to activzte my vacuum operated exhaust cutout,
this way i can set my tach indicator to say 3500rpm, everytime the needle hits 3500 or whatever it is set to my cutout opens,
this is my plan i just dont know where to pick up a signal from.
i understand i will need to install a relay as is will only be a low amp signal.
any ideas
thanks in advance guys

 

Welcome to CL! Though I must say I'm quite surprised that over the course of a year, you did not find the subforum dedicated to your specific model. I went ahead and moved your post.

 

I assume you are going to set the rev warning ring to light at that X RPMs. That will result is just a color change of the tach indicator ring. If the red light is actually a different LED than the normal green and orange, then you may have a chance, but you are not going to drive a relay with that signal or what drives the LED's. I'm not sure if it is a 12V, 5V, CAN bus message or what that drives the lights in the cluster. I doubt it's an actual discrete signals from the ECU and more likely CAN bus. Regardless, you're going to need a buffer of some sort to give you enough current to drive a relay and probably one with some hysteresis so you have the cutout stays open for a bit . Unless you're and EE or know one that can provide a proper circuit for you, I'd advise against this. Otherwise, you're gonna burn something up.

 

I can't help you with the pin out but with the display in hand you should be able to track down the LED responsible for lighting the ring. That said it is likely a bi-color LED. i.e. one package, 3 pins, and two colors.

Also I would advise against a relay tap. Relay coils have resistance this could impact the circuit. Relay coils also induce charge voltage into the circuit when the field collapses and require a protection diode to prevent damage to the drive circuit.

Suggest you use a MOSFET device. They draw no current to speak of, have high gate impedance, and can drive the reed relay pretty easy.

That said I would start under the hood and look for a usable signal there. Older Yoda COP ignition modules had Tach output and perhaps a circuit that samples the frequency could be used instead of tearing the dash apart?

PS would love to find an FSM for these so we know how they work. Anyone know where I can buy one?

 

Yes i see your point, it looks like either finding somone who could make me a box of trickery or somthing completly different.
just thought it would have been a nice touch to be able to set when i wanted the cutout to open.
oh well next idea i guess, 🤔🤔

 

Put a micro switch on the throttle pedal so when you get to a certain spot the exh opens.

 

Yes i did think about the micro switch on the pedal, i guess it will be an easier and safer option,
i will have a look at the pedal layout and fabricate a bracket.
thanks

 

Combined with a vacuum sensor you could fine tune it a bit.