Now I have to find a switched power source, on all the time whether starting or not. ( BTW, always disconnect you jumper wire from the battery first because if the other end gets grounded, it will smoke that wire in a hurry.Ask me how I know that.). YES ! that made everything work including the tach. So I ran a test wire directly from the + battery post to the + coil post. JUST NOW FIGURED OUT THE PROBLEM ! with wifey to run the ignition switch and me on the test light, I found no power to the + side of the coil with ignition switch on -until engaging the starter motor and then there was power there as long as it was turning over. Used a 5 amp fuse and ran that to the tach. I ran that wire to an auxillary aftermarket small fuse box, so It would be easy to hook up other switched 12 v things if I need to. No places to plug in a wire into the fuse box, so I had to slice in a wire to the black wire coming into the fuse box from the ignition switch. That leaves the power to the tach when ignition switch is turned on. My tach light is correct because the variable dimmer works in the tach light. I think the volt limiter you mention is only for the gauges. Up to installer how he color codes the wires. The new Bosh " super Sun" retro tach does not have color coded wires, only studs on the back that has a label telling what to hook them up to. It has me stymied.MOĬlick to expand.Thanks for your input. Problem : Turning over the starter motor with the ignition key switch, the engine will start and the tach will show some engine rpm, but as soon as I let off the key for the engine to continue running, it shuts off the engine and of course the tach drops to 0 RPM. one post goes to the negative (-) side of the coil. One post goes to dash instrument lights.One post goes to 12 volt switched source, so power on when ignition key is turned on.one post goes to ground. Now, I am installing a new Bosh tachometer retro Sun Super. The black wire from the Pertronix is hooked to the negative side of the coil. ) As per the instructions, the red wire from the Pertronix is hooked to the positive side (+) of the coil which is also the post that 12 volts from the ignition switch goes to. And the Pertronix coil that a ballast resister is not needed for. Using stock 1968 318 Mopar non electronic distributor with the standard Pertronix points conversion.