Hey guys, Im looking to install a Tacho in my 91 3.9l Dakota. It is an Automation truck so there is no factory tacho. I want this gauge so I can keep an eye on the rpms at different times of use. I know that I need to hook the Tacho wire up to the negative side of the coil to get the rpm readings but I do not know where an ignition switched 12v circuit is that I can tap into right off.. If anyone has a 87-91 TBI and know where an ignition switched 12v circuit is I'd be grateful to know what you know! FYI: I havent invested any time in looking myself yet for the 12v circuit. I just started looking for gauges tonight. Im sure I can eventually find what I need with some looking. This route may be faster! Thanks!

 

take a test light and check fuses in the fuse box while turning the key between acc and off then when you find the circuit you want just use an add-a-fuse. most poeple go this route because its easier and they use the radio circuit.

 

Thanks Shadow! I just bought a test light a couple weeks ago. ..I had forgot about it already! lol ill look for the radio circuit or find an unused fuse slot thats switched. Great idea.