Tach install question

[VIRstang]

I'm having trouble installing an Autometer tach in my 99 GT. I bought the adapter that is required and wired it as suggested. Now the motor is running like crap and the tach needle just jumps up and down. Any suggestions?

 

[LaserRed01GT]

There are 4 wires that come off the tach adaptor. You need to put the black to ground. Make sure it is a good ground. The grey wire goes to the green wire on the tach. The red/green and red wires go to the coil driver wire that runs through the main powertrain harness. This harness is the big one that runs across the top of the firewall and makes a turn down by the back of the driver's side fuel rail.

If you mount the tach adaptor somewhere on the driver's side firewall, you can open the harness right by the back of the fuel rail and there will be one solid red wire (actually looks dark pink). Cut that wire, and splice it into the red/green and red wires coming off the tach adaptor. You are completing the coil driver circuit through the tach adaptor. Clear as mud?

 

[1low03gt]

Taken right from autometer tech support.
The below info is for '99 to '00.

Tachometer Signal Wire Installation
for 4.6L engine(s)
Must use model number 9117 Auto Meter tachometer adapter. Locate the large, square 42 pin wire harness connector in the corner of the engine bay where the passenger fender meets the firewall. Pop the plastic cover off of the top of this conector to expose where the wires enter the connector and to expose the wire pin numbers. Locate pin number 34 which will be in the corner of this connector and will be a white wire with a blue stripe. Cut this wire in half so that you now have two cut halves. Hook the red of the adapter to the cut half coming from the connector. hook the red/green of the adapter to the other cut half. Ground the black wire of the adapter. The gray wire of the adapter will now provide you with a good tachometer signal.

The below info for '01 to '04.

Tachometer Signal Wire Installation
for 4.6 engine(s)
Must use model number 9117 Auto Meter tachometer adapter. Locate the large, square 42 pin wire harness connector in the corner of the engine bay where the passenger fender meets the firewall. Pop the plastic cover off of the top of this conector to expose where the wires enter the connector and to expose the wire pin numbers. Locate pin number 34 which will be in the corner of this connector and will be either a red wire or a red with a green stripe wire. Cut this wire in half so that you now have two cut halves. Hook the red of the adapter to the cut half coming from the connector. hook the red/green of the adapter to the other cut half. Ground the black wire of the adapter. The gray wire of the adapter will now provide you with a good tachometer signal

LaserRed01GT is correct in everything,minus the colored wires to your year.No biggy. But you could have the same wire color as the '01 to '04,cause ford would do something like that,so that is why i posted both tech supports up.
Did this myself when i first got my stang in '03.Good to refresh myself.LOL!!

 

[LaserRed01GT]

Thanks for clarifying that 1low03gt. Autometer is correct that most of the 99-00's had a WH/BU coil driver wire. But, you were also right that RD and WH/BU wires are sometimes seen on different years. It can only be either color though.

 

[VIRstang]

Thanks guys! The adapter instructions had us wiring to each coil. I will try it this way over the weekend. I unhooked the tach and the car is running great again. We must of had something wired wrong.
Ben

 

[VIRstang]

It worked like a charm!

Thanks guys!

 

[LaserRed01GT]

 

[1low03gt]

No prob's!!