Leaderboard

Most tachos, work by connecting the pulse train input wire for the tacho, to the negative terminal of the coil, which was traditionally, in a CB dissy; simply connected to the points. You could try simply connecting it to the negative terminal of your coil. If that doesn't work, then try the IGt signal. That is a nice square wave, & has some dwell information in there, as a result of the width of the pulse, which will not make any difference to the tacho reading, as it is only interested in the frequency, of the pulse train.. I notice that the ignitor in the diagram above, does have a "TAC" output, but as there is no wire colours depicted, that may make it difficult to identify, unless there are some markings on the ignitor itself. If you had access to a CRO, or a multimeter, that measures frequency, then you could probe around, until you found a signal that changes frequency with RPM. Unfortunately, I've never come across one of these Toyota ignition systems in my travels, so don't have any personal experience. Strangely, when I built the ignition system in my KE30 Corolla, years ago, I instigated a similar system, where under starting conditions, the coil is sent a signal at base ignition timing, of 10-12 degrees BTDC. Once the engine is running, the ignition system, then switches over to the electronic advance system. It does have the advantage, that the engine starts instantly always; & if your ignition system ECU & ignitor fail altogether, you can flick a switch, & get on home, in "limp mode", with just the base 10-12 degree advance. Somewhere on this forum, I described this system, years ago. I'll see if I can find it. Here it is . . . . . . Cheers Banjo