The red wire will go to a key switched power source. The black is your ground, the white will be tied into the dash lights (or headlight switch). The green wire is your signal. On traditional ignition systems, this will go to the negative side of the coil. MSD style ignitions will typically have a tach output terminal on the control box. in some cases (such as distributorless or coil-on-plug style ignitions), you will need to use our 9117 tachometer adapter to get a good tach signal. We do many installations here for reference, so I will likely have information specific to your application if you need. Hope this helps, please let me know if i can be of further assistance.

Best regards,

Joseph Mills
Auto Meter Products, Inc.

There are a couple diesel tachs that we offer in our line. We have two 2 5/8" pedestal mount tachs that use an alternator pickup to get an rpm signal. They are then calibrated on the unit itself. We also have a 5" Pro Comp Memory tach that uses a pickup that senses the harmonic balancer. This unit was designed for tractor pull style vehicles, but will certainly work in any street application as well.