Bartman Posted October 4, 2004 Share Posted October 4, 2004 I have a 1973 240Z that I purchased a couple of months ago and it came with a Crane XR700 Electronic Ignition system installed in it. It seems to work pretty good, but the tachometer isn’t working. I’ve been able to find some posts of people that are using this and still having the tach work. It seems to be wired correctly, but I’m not sure. Can someone out there who has this system tell me how they wired it so that the tach works Quote Link to comment Share on other sites More sharing options...
Bartman Posted October 8, 2004 Author Share Posted October 8, 2004 I fixed my tach this morning I was able to find an ignition wiring diagram at http://zhome.com/ZCMnL/tech/ZXPertronix.htm. There are stock diagrams as well as diagrams for a Pertronix Ignition, and a ZX electronic ignition. I also used the diagram in the XR700 documentation I found at the crane website. One of the differences was that my electron ignition was wired to the ballast resistor instead of the coil. I changed this and the tach still didn’t work. Another thing I noticed was that the tach seemed to work while my engine was cranking but not after it started. According to the information I found and these diagrams, the difference is that while the engine is starting the ballast resistor is bypassed. After the engine starts the ballast resistor is used. I finally discovered that the person that installed this unit added a wire from the ballast resistor to the positive side of the coil. As soon as I removed this wire everything worked, including my tach. I am still using the old positive loop tach, and now it works great. I can only assume that the flow was going through the ballast resistor straight to the coil instead of flowing through the tach. Quote Link to comment Share on other sites More sharing options...
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