Guest rommelrommel Posted September 3, 2005 Share Posted September 3, 2005 Hey, got a little problem with my 72 240 that I hope someone can help with. I was cleaning up misc wiring underhood a while back, and on a trip back and forth to the ignition diagnosing, I managed to bump my starter a bit with a wire running thru my fan SInce then, my tach doesn't work, and my car eats ignition coils. I've figured it out enough to know that it's eating coils up because the coil is getting 12v on RUN instead of just on START. Wire is Red/Blue Stripe, and comes out of the main wiring harness at the front of the car. I'm inept with reading wiring diagrams so can someone please tell me where this wire is supposed to go? Quote Link to comment Share on other sites More sharing options...
getZ Posted September 4, 2005 Share Posted September 4, 2005 rommelrommel, The + side of the coil should have 12 volts in either the run or start position. However the - side of the coil is grounded through the distributor. It is one of the fuctions of the distributor to complete the ground side of the circuit in order to energize the coil. I was looking at the autozone schematics, but they may be a bit to oversimplified. http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/1d/1d/80/0900823d801d1d80.jsp The Nissan schematic from CD is extremely difficult to use so I hope this works for you. It looks like the blk/white wire is what is used to ground the coil and hook up the tach as well. I'm not sure which wire you mean when you say red/blue at the front main harness, but at the front of my 72, red/blue wires connect up to another red-blue wire. That red-blue wire powers up a lot of accesories depending on where you are talking about. Hope this helps. Quote Link to comment Share on other sites More sharing options...
Guest rommelrommel Posted September 5, 2005 Share Posted September 5, 2005 Isn't the function of the ballast resistor to lower the coil voltage? The tach stopped working when that red/blue wire got broken, so I always assumed they were connected somehow. I guess I should take a look at my coil/distributer wiring again and make sure it's all right. The car runs fine as is tho, so I'm not sure what's up. Quote Link to comment Share on other sites More sharing options...
getZ Posted September 6, 2005 Share Posted September 6, 2005 I'm not 100% positive what that resistor is for, but lowering the voltage is probably a good guess, either that or it is to prevent a direct short. Are you still eating up coils? Quote Link to comment Share on other sites More sharing options...
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