# Tach wire



## thesaint421 (May 19, 2006)

Hey guys new around here, but have a somewhat big problem... I installed a alarm/remote start combo onto my 91 nissan sentra. everything works perfectly but when I remote start the car, it starts then dies 5 seconds later. I have connected everything correctly, but the tach wire. the car isn't fuel injected so I can't grab one off the injector. my wiring says to use the green/yellow off the coil, but I don't have that wire on the coil.

My wiring information also says i could use the black/yellow in the ignition harness as the tach wire, is this true? if not, can I grab it off the ECU? if I can grab it off the ECu then I wire colour and the location of the ECU would be greatly appreciated.

regards, mark


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## Twiz (Aug 24, 2004)

What color are the two wires that lead to the ignition coil ? Start the engine and backprobe both wires from the ignition coil with a voltmeter set on AC voltage (12v to 20v scale is fine), use chassis GND for (-) probe. The one that shows 1v - 6v is your tach wire.


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## dmroberson (Jun 24, 2004)

thesaint421 said:


> Hey guys new around here, but have a somewhat big problem... I installed a alarm/remote start combo onto my 91 nissan sentra. everything works perfectly but when I remote start the car, it starts then dies 5 seconds later. I have connected everything correctly, but the tach wire. the car isn't fuel injected so I can't grab one off the injector. my wiring says to use the green/yellow off the coil, but I don't have that wire on the coil.
> 
> My wiring information also says i could use the black/yellow in the ignition harness as the tach wire, is this true? if not, can I grab it off the ECU? if I can grab it off the ECu then I wire colour and the location of the ECU would be greatly appreciated.
> 
> regards, mark


What kind of alarm system is it? You have the tach sense module attached? (optional accessory, not included with original system). If you do not, you can adjust the system to voltage sense, high, then you won't have any more problems. I ran across the same problem on my 04. Didn't have the tach sense module, changed the system to voltage sense, still don't have the module, and my remote start works fine now.


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## thesaint421 (May 19, 2006)

Hi guys, I don't have the car with me right now, so I can't list off the wire colors from the distro at the moment. as far as the alarm, it's a viper 791 xv, the tach wiring is built in, and I don't want to go to voltage sense because it won't work with my battery properly.

regards, Mark


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## thesaint421 (May 19, 2006)

anyone have any ideas about the possibilities that I mentioned, with using the 2nd ignition wire, (black/yellow) or going right to the ECU? this is what my wiring info says about the tach options... "Cold Start Wire- BLACK/YELLOW At Ignition Switch Harness"

Mark


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## Twiz (Aug 24, 2004)

Okay I have the 791 XV installed in my Sentra... now if you turn to page 11 it says:

"finding the tachometer wire"

Did you read that part ?


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## Twiz (Aug 24, 2004)

Okay I found something on page 48 in your installation guide... if you look down the page where it says:

3-6 VOLTAGE CHECK HI/LOW 

That's an option that'll make your remote start work and the engine won't stop anymore cause of voltage drops. You have to set this option to LOW. However I recommend connecting your tach wire (Violet/White tach input wire) for a more accurate reading.

Don't connect the tach input wire to BLK/YEL at ignition switch !!


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## thesaint421 (May 19, 2006)

yes I understand how to find the wire, but the wires at the coil don't register more than .3-.8 VAC with the engine running and the throttle being raised... I think I will have to grab the tach signal off the ECU, does anyone know the wire colour, and the location of the ECU?

thanks Mark


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## Twiz (Aug 24, 2004)

Read the two stickies at the top of the B13 forum... The tach install write-up and the B13 FSM which includes wiring diagrams. Good Luck!


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