HELP!!! Tach Adapter 9117 Autometer COYOTE problems HELP!!!!!!! im stuck

[35 Ford Hoonatruck]

Building 35 ford truck with the Coyote motor. My problem is that my Tach is not working. I purchased an additional tach adapter 9117 in hopes that I got a faulty one but they are both acting the same......I am getting NO voltage out of the Gray wire ( the one that goes to the gauge ). The way I have it wired up is I have the Red/Green wire going to my coils (purple wire) and the Red wire going to the computer. I cut the purple wire just before the harness and split it there. I have an extremely good ground of which I have moved multiple times to eliminate that.

Soooooo here is what I have.

VideoCapture_20190902-142511[1].jpg

When I turn the truck on Start and ACC (without starting the motor) I get 13.3V to the Red wire which is connected to the computer
When I start the truck ( and yes it runs which means the coils are getting voltage through the 9117 ) the voltage dips then stabilizes at 14.7volts.
then I check voltage to the Gray Wire and I have nothing.....not with the motor running or with the motor off but with ACC on.

Now for some reason I checked this......while the motor was running I disconnected the ground from the 9117 and all the sudden I got voltage to the Gray wire 13.3volts on ACC only....then 14.7volts fluxuating? I get the same voltage that the Red/Green wire is getting....almost identical.


Please tell me what I have done wrong......this gremlin is killing me.

Mahalo

Doug

[35 Ford Hoonatruck]

OK i am such an Idiot!!!!! I had the input and output switched.....because of how the harness was sitting in the engine bay where I spliced in the wires for the 9117 the incoming and outgoing wires looked like they were going the right direction!!!!! but they were not, I had the Red and Red Green switched.....and thus no Tach signal!!!!!! But I am jumping for JOY as I have solved my last Gremlin in my electrical system and now the body can get mounted!!!!!!! HORRAY