77 ignition harness
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77 ignition harness
any suggestions advice and information would be greatly appreciated, im trying to locate the amperage of the fusible link from the battery and horn relay side of the starting solenoid to the ignition switch its supposed to be black and/or yellow (i am assuming this is supposed to be the main power to the ignition switch) and i cant find a direct answer on what the voltage at the coil is supposed to b with the key in run and when cranking its a 77 300 inline six im using the ignition module to distributor/coilharness from a 400(year unkown) the ignition module is new and regular altitude for the 300 inline six (i was asked if high altitude, any info on the high altitude would b grateful) i am curently wiring in a new 77 ignition switch and voltage regulator. the wiring diagram i have isn't the greatest and doesn't say whether the ignition module or the voltage regulator are grounded. im running this engine on a stand b4 instal and have no extra harnesses available.
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Ignition module gets it's ground through the distributor. When you plug the dist into the module, one of the wires is the ground and is bolted inside the dist to the dist body.
When cranking the coil gets battery voltage, which could be anything from around 9 or 10v up to 12v. It depends on the condition of the battery, the starter, and how hard the engine is to turn over.
When the engine is running, the coil gets a reduced voltage. The voltage is reduced through a special resistance wire(ballast resistor) in the harness that runs between the coil and the ignition switch. With the engine running you will get in the neighborhood of 9v on the coil +.
Here's a diagram. This diagram has the cranking bypass feature made into the solenoid. The later trucks had this built into the ignition switch.
The regulator body does need to be grounded. Usually one of the mounting bolts has a ring terminal around it, and this wire goes to a good ground somewhere, since the regulator is sometimes mounted on the plastic inner fender.
When cranking the coil gets battery voltage, which could be anything from around 9 or 10v up to 12v. It depends on the condition of the battery, the starter, and how hard the engine is to turn over.
When the engine is running, the coil gets a reduced voltage. The voltage is reduced through a special resistance wire(ballast resistor) in the harness that runs between the coil and the ignition switch. With the engine running you will get in the neighborhood of 9v on the coil +.
Here's a diagram. This diagram has the cranking bypass feature made into the solenoid. The later trucks had this built into the ignition switch.
The regulator body does need to be grounded. Usually one of the mounting bolts has a ring terminal around it, and this wire goes to a good ground somewhere, since the regulator is sometimes mounted on the plastic inner fender.
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thank you...would u happen to know the resistance of this ballast resistor and how i might make one? i was aware of the resistor but all the parts stores say its a fuse, i show them the diagram in their book and then they are speechless and say they cant help.
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i was told that it was supposed to b 1.0 to 1.5 ohms and figured id try radio shack cuase i figured they would at least have an idea, he looked at me like i had 2 heads but proceeded to explain that all wires have resistance and that i could just use a length of wire that provided the resistance needed. any ideas?
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Go to the parts store and ask for a resistor for a Chrysler product. They are close enough to work, and are large enough, since they get hot when the engine is running. If that's not good enough, go to Autozone's site and pretend you have a old Chrysler and look for the part number of the resistor. The guy behind the parts counter should be able to work with that I would think.
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i actually just got back from the parts store and after almost an hour of cross refrencing part numbers i ordered what should be the correct part. i was going to test it with my dvom and make sure before i install it in my harness....and i think im going to chance it and im just going to fuse the ignition at 20amps thank you franklin2, i appreciate ur help reps given.....its going to b 4 days till it arrives so ill let u know when it comes in, im going to start lookin at the chrysler stuff now so im prepared if its not corect
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i reread your post, i need to take 12 volts to roughly 9 volts with the resistor, correct? can u explain how to calculate the amount of ohms needed to do this?
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From: Virginia
Just go by what values you said you picked up somewhere else. My book says 1.05 to 1.15 ohms. So long as you are in the neighborhood it will work. I have never actually measure the resistance of a Chrysler resistor, but I have recommended them for years for people with Fords that had a problem with their original resistance wire, and no one has ever complained that it didn't work.
By the way, if you have the complete original Ford harness from the coil in to the ignition switch plug, then you should already have the resistor incorporated into the harness. Ford used a special piece of resistance wire spliced into the wire going to the coil, and it's usually very near where the ignition switch plug is located in the harness. Old points harnesses had it, and all the duraspark harnesses had it, only the later TFI engines did not use the resistor, but some actually had it anyway, since starting in the mid 80's they had trucks with TFI ignitions as well as duraspark ignitions. Those harnesses have empty plugs laying under the hood depending on what engine they were equipped with going down the line.
By the way, if you have the complete original Ford harness from the coil in to the ignition switch plug, then you should already have the resistor incorporated into the harness. Ford used a special piece of resistance wire spliced into the wire going to the coil, and it's usually very near where the ignition switch plug is located in the harness. Old points harnesses had it, and all the duraspark harnesses had it, only the later TFI engines did not use the resistor, but some actually had it anyway, since starting in the mid 80's they had trucks with TFI ignitions as well as duraspark ignitions. Those harnesses have empty plugs laying under the hood depending on what engine they were equipped with going down the line.
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unfortunatly i dont i only have the distributor to ignition module harness im building the rest, been looking for a harness, may have found one but idk yet, i know the truck is there not sure about the wires
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It will run without the resistor for a time. The factory runs it without the resistor while cranking. But the coil and the module will run hot and it will shorten their life. But no, it will not "zap" the module. Make sure you are using the correct coil also. Some coils draw more current than others, and no, they will not zap the module either unless they are faulty, but the higher output coils will also make the module run hot and could shorten it's life.
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ok then...musta been a bad module. got the new one and when the wires are on the coil im only getting 3.06 volts starting and in run, off the coil im getting 12.22 in run and in start i have 12.16 that trickles up to 12.22, i did this testing at the horse shoe plug on the red wire the green wire off the coil was reading .655 volts in run and start and in i had 1.96 volts in run and it dropped to 1.94 volts and trickled up to 1.96 in start engine not cranking. im going to buy a new coil anyway, but what would cause this. and sorry for all the questions, this is a learning experience for me but i really do appreciate all your help.
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