mid-tn-mustang 10 Report post Posted January 2, 2011 Can i reuse a replacement underhood/headlight wiring harness from a tach car in my non tach car? The underdash wiring harness in my car is a nontach and I am using an aftermarket tach. What would i need to do with the wires going to the tach? thanks Quote Share this post Link to post Share on other sites
danno 128 Report post Posted January 4, 2011 If you will be using an aftermarket tach, go with a seperate wire harness for the tach. A tach underhood harness will not work with a nontach under dash harness. There are other differences, like the tach version had idiot lights for alternator and oil pressure, the tach version had gauges. There is a connector behind the fuse block that connects the underdash to underhood cables, and the wires in this connector serve different purpose in the 2 connectors. Besides all that, the actual wires for the tach of a tach engine wire harness do not have the tach in them at all. It uses the engine harness for a tach signal. The engien harness goes through the firewall in a different place. It has connections for the oil pressure, temperature, and ingition wire. The ignition wire, from the coil to the key switch, is what the standard tachometer uses to sense speed. Quote Share this post Link to post Share on other sites
