robsquikz28

iTrader: (246)

awesome mods delete, thanks

Nelapse

iTrader: (3)

Electricity always goes to the path of least resistance. I doubt your box is bad, but I would double check your wiring. If you have a schematic for your box I would make sure the tach signal circuit doesn't corrupt there. Does that box have a v6-v8 switch?

robsquikz28

iTrader: (246)

nope just v8 and i read somewhere else that peeps were having the same issue where the pcm was disrupting the box and not allowing the tach to work properly but there was no solution.

MetalAuthority

iTrader: (1)

Just had my 685 installed this friday. Havent programmed it to the settings I want yet though, but I havent had any tach issues. Is yours a digital display one? I know mode 7 is a tach checker...

robsquikz28

iTrader: (246)

yes its the digital box....but to tach check, all you do is set what you want as your rev limit then turn the key off and back on real quick, it will then show setting 1. After that your good to go, the box now recognizes the tach signal.
This is weird only cuz I have installed this dozens of times on carb'd setups and no problems now when i go to install on Lt1 car i have an issue, what makes it worse is that its a sidejob!

DopdBrd

iTrader: (25)

Ok, if I am understanding you right, you spliced into the back of your PCM for the Tach signal?

Why did you do this and what did you hook it up to?

If you use the tach output on the box you shouldn't have to splice into the Tach lead coming out of your PCM. Since the Mallory is plugged into your coil and is essentially running you ignition, THAT is where you get your tach signal from. There is no need to splice into your PCM.

But maybe I'm just misinterpreting you.

~BuMps AloT~

iTrader: (5)

You dont have to connect the tach output wire on your box to your pcm. That is there so you can run an after market tach off of.

robsquikz28

iTrader: (246)

got it, thanks guys wiring was wrong i figured it out today then i read the posts...wth