2002 Mustang GT, Viper V790xv

Hello everyone-

Got a tachometer question for my 2002 Mustang GT. The Viper V790xv manual states the tachometer can be located at a coil pack and will be around 3-6V AC. The wire color chart I am using says I can find it at the PCM as lt GREEN / WHITE. However when the engine is running my voltometer says the voltage is 30.2-30.4V AC. Any ideas on what I am doing wrong? Also, woud you recommend pulling it from the wire running to PCM or just off of a coil pack. I ask because I think it would be easier to run a wire through the firewall to a pack then all the way over to the passenger side to hit the lt GREEN / WHITE wire at PCM. I also tested out a wire off of another pack and it had the same voltage however still not the voltage that the manual states.

Any ideas greatly appreciated.

Thanks,

Kyle

• For the 3.8L motor, use the dk. blue/lt. green, RED / lt. blue, or the pink/white. All of these wires are found at the coil pack.
• The 4.6L motor uses a separate coil for each cylinder. Go to any coil and use the wire that is NOT red or WHITE/ lt. blue.
• Make sure that you have the RED lead on the DMM on a 12 volt + and the BLACK lead on the target wire.

Thanks for the reply.

I am pretty sure I have the right wire for the tachometer per your instructions however the voltage question concerns me. Your reply says to have RED Lead to 12+ and Black to target. However I think the Viper instructions state it the other way around. I'll read them again.

I just don't want to hook the wrong wire that has higher voltage than the unit is expecting and blow it up or something :)

Thanks,

Kyle

That could very well be my problem than cause mine is the cheap sears one.

Thanks for the help,

Kyle K

the problem is the range on your dmm, if you can change it go to 0.00 and try it.