Tach Wire??

Gearhead843 · #1 08-16-2011, 05:16 PM

My new alarm system for my SVX requires a tach wire. I've done numerous installs and all the usual things do not work! It says the tach wire should show between 1 and 6v AC depending on revs. I have the instrument cluster out as well. I've tried tapping an injector, tried the ignitor, and have had NO LUCK. I have a 1997 OBDII SVX. Any ideas?

92snowmachine · #2 08-16-2011, 05:47 PM

you could try tying it to the crank or cam sensor. this should give you a 5v ac waveform. why does it need a tach wire for the alarm anyway?

Gearhead843 · #3 08-16-2011, 05:49 PM

Remote start. What wire on the crank and cam? And where are these sensors located on the SVX? I haven't had to replace these yet, luckily.

92snowmachine · #4 08-16-2011, 05:57 PM

don't remember the wire colors off hand but both sensors only have two wires so you could just try one then the other. the cam sensor is on the driver side cam, just behind the timing cover. the crank sensor is in the middle of the engine in the front, might have to move your alternator to get to it. i would try attaching it to the cam sensor first just to see if it will tolerate that type of signal.

icingdeath88 · #5 08-16-2011, 06:50 PM

There is an RPM signal on the ECU plug... There's an ECU pinout kicking around the site somewhere. Try searching for that.

Gearhead843 · #6 08-17-2011, 06:41 PM

Quote:

Originally Posted by icingdeath88

There is an RPM signal on the ECU plug... There's an ECU pinout kicking around the site somewhere. Try searching for that.

I found said wire, and traced it all the way to the instrument cluster. It outputs around 20v AC. The signal I need has to be between 1-6v AC. Any ideas?

EDIT: It also says I can use Oil Pressure or High-Voltage Sensing, however due to COP's I cannot use the High-Voltage Sensing.
EDIT: The yellow wire thats supposed to be tach that I tested goes down in voltage when I rev.

Gearhead843 · #7 08-17-2011, 11:48 PM

Nevermind the question. I've thrown in the towel, and will just use a tachless setup. I've tested it and it works pretty well. Plus, I don't live in a cold climate, so it won't have to worry about failed starts. Thanks for all the helpful info guys!