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ECU tachometer signal


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Working on wiring for a VQ35 and thinking about tachometer signal.  Since the VQ's all typically use a canbus system with a combination meter control unit, this becomes a bit confusing when hooking up a traditional tach.  There's one output from the ECU that assists with the power steering system called engine speed signal.  I can't find anyone referencing this signal in other VQ swap threads.  The FSM gives the following waveforms and I'm having a brain fart trying to determine if this is suitable for a regular tach, since I'm not clear what type of signal the tach needs.  This seems to indicate that the signal will have 6000 pulses a minute at 2,000rpm - is that correct for a 6 cylinder tach input??  I know the voltage may be too low for some tachs...

 

enginespeedsignal.jpg

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On the VQ35 like the SR20 there is no "RPM" wire. According to the manual the engine speed signal is also used for fuel cutoff at high idle. Funky shit going on there with multiple inputs, might not be the best tack signal.

 

I don't know what tack you have, but I used a coil trigger wire to run my Speed Hut Revolution Tack. I just had to tell the tack how many cylinders there were. 

 

Looks like your cylinder 1's coil trigger wire is yellow and red, pin #62 coming out of the ECU. 

 

Make sure to disconnect the battery, and Good Luck!

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Those waveforms are a 5V signal, so that won't work for a traditional tach.  You need a 12V signal.  

 

You may be able to modify a 4-pin HEI module to transform that signal into a tach signal by hooking the waveform and a ground to the input terminals (both wires from the crank trigger), then add power to the module and use the tach terminal for your signal.  

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