spiderwebfx

High-voltage Tacho and Link

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Howdy OS'ers

 

Hoping some of you here may be able to help me with something.  I've put a Link ECU into the S12, and am trying to figure out how to get the tacho to work.

S12 Silvia, originally CA20E, now has S14 SR20DET and Link Monsoon ecu.

I was having a read through this thread; 

But tbh, I don't really understand it.

So the Link has a 12v output.

I'm not exactly sure on the S12 tacho input signal type, but attached is a photo of the circuit board (R9 is the first resistor on the tacho signal wire).  However, I would prefer to do it with the relay option as I don't want to risk damaging the board.

I used to have it driven off the S14 coils by using four diodes (1N4004) on each signal wire (from the ignitor chip) into one, then straight into the tacho.  This worked, but my tuner has said he'd prefer not to have anything that can interfere with signal on the coilpacks, and I've also converted to S15 coilpacks if that matters.

s12_tacho_board.jpg

If it's relevant, the larger of the resistors with writing is 82ohm 5% 2w (R1) and the smaller (R2) is 43ohm J 1w. (Not sure what J means)

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Just short out the first resistor in tachometer signal input. That chip is fine with a 12v square wave so just feed it directly from link output.

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Find a tacho that does work with the link(most should) and retro fit it into the instrument cluster and put your faceplate on it.

That's what I did when I could not find a PWM speedo within my budget of no-money. I just carved out the plastic speedo housing, mounted tacho internals in the hole and screwed the speedo faceplate on it. The tuner calibrated it on the link when it was on the dyno. Only downside for me is no odometer.

Ideally you would have a spare instrument cluster in case you made a mess of things. 

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9 minutes ago, Adoom said:

Find a tacho that does work with the link(most should) and retro fit it into the instrument cluster and put your faceplate on it.

That's what I did when I could not find a PWM speedo within my budget of no-money. I just carved out the plastic speedo housing, mounted tacho internals in the hole and screwed the speedo faceplate on it. The tuner calibrated it on the link when it was on the dyno. Only downside for me is no odometer.

Ideally you would have a spare instrument cluster in case you made a mess of things. 

I have thought about doing that.  Only problem is I haven't been able to find an rpm gauge i can try it with

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Done, a few hours of messing around, but it now works. I have an Auto Meter tacho internals on the back of my S12 cluster.  I'll get the tuner to fine tune it tomorrow while it's getting it's tune done.  Cheers for the help.

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