Slant Six Forum :: Getting gray hair soon..

If the car cranks in ON, you've almost certainly got the contacts at the starter relay swapped, so the power to the coil (via the ballast) is telling the relay to turn on.

You need the relay to get the car cranking and you need to get power to the coil and any ignition module while its cranking. The car will start better with 12V at the + coil, but will also work with ballast in series (6-8V at the +coil), but you want the full 12V at a module. If the ballast has power when you crank, you don't absolutely need to bypass it. A test light will quickly let you know if you've got power at the + coil and module.

One fellow w/ an A-body I met just bypassed his ballast altogether and ran his stock coil with points for ~6 months, until, in his words, the coil "exploded".

Author:	monzav8 [ Thu Feb 24, 2011 3:53 pm ]
Post subject:	Getting gray hair soon..
Bought a 1977 Dodge B300 for some months ago, where there has been some carpenters wiring the car it seems. Missing all the wires in the front and mostly inside. My headache is how to get it running again. Ballast resistor, ICM etc wasn't there when I bought it, so my question is: Which items are needed to complete the ignition system and are the starter relay necessary (Missing that too) ? Also, the coil needs power when the ignition is on "ON" and "RUN", right? I used the wirediagram I found under FAQ and if I try to wire it like the diagram says, the engine starts to crank when at "ON" position. The main problem is that the old ignition system and all the wires for the engine is GONE, and i'm having a hard time figuring out all the wires and where they go. Got one missfire today and after that it "died" Regards Andreas

Author:	KBB_of_TMC [ Thu Feb 24, 2011 4:28 pm ]
Post subject:
If the car cranks in ON, you've almost certainly got the contacts at the starter relay swapped, so the power to the coil (via the ballast) is telling the relay to turn on. You need the relay to get the car cranking and you need to get power to the coil and any ignition module while its cranking. The car will start better with 12V at the + coil, but will also work with ballast in series (6-8V at the +coil), but you want the full 12V at a module. If the ballast has power when you crank, you don't absolutely need to bypass it. A test light will quickly let you know if you've got power at the + coil and module. One fellow w/ an A-body I met just bypassed his ballast altogether and ran his stock coil with points for ~6 months, until, in his words, the coil "exploded".

Author:	Nongan [ Thu Feb 24, 2011 4:35 pm ]
Post subject:
Here is a wiring diagram, I don't know if this is the same one you looked at and your supposed to have 12 volts to the coil with the key on the ON position

Author:	monzav8 [ Fri Feb 25, 2011 1:23 am ]
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Quote: If the car cranks in ON, you've almost certainly got the contacts at the starter relay swapped, so the power to the coil (via the ballast) is telling the relay to turn on. You need the relay to get the car cranking and you need to get power to the coil and any ignition module while its cranking. The car will start better with 12V at the + coil, but will also work with ballast in series (6-8V at the +coil), but you want the full 12V at a module. If the ballast has power when you crank, you don't absolutely need to bypass it. A test light will quickly let you know if you've got power at the + coil and module. One fellow w/ an A-body I met just bypassed his ballast altogether and ran his stock coil with points for ~6 months, until, in his words, the coil "exploded". The things is, I don't got a starter relay. I bought a new starter and a new coil that didn't need a ballast resistor. I got the engine cranking without a starter relay, just trough the starter solenoid. Do the coil get its "RUN" power via the starter relay, ICM or the ignition key? Regards Andreas

Author:	KBB_of_TMC [ Fri Feb 25, 2011 3:55 pm ]
Post subject:
Sorry, I don't have the stock schematics handy, but I'll assume it's similar to earlier models and doesn't run a computer, just a ignition module (ECM) (4 or 5 pins in a pentagonal connector). The ignition (key) switch in RUN provides 12V to the ballast resistor, the ECM, and the voltage regulator; they're all tied together. The coil + gets its power from the ballast resistor, and the coil - goes to the ECM. (Some later Mopars with computers put the ballast resistor inside the ECM on the - coil side, but I'd be surprised if yours is that way.) With ignition in RUN, car not running nor cranking, the ignition switch ought to send 12V at one end of the ballast, the ECM, and voltage regulator. You ought to find 5-8V at the other end of the ballast and at the coil +. The coil - ought to be <1V. Without consulting a detailed schematic, I don't remember whether the ignition switch provides power to the ballast & ECM in START. Usually, the starter relay's connects 12V to the end of the ballast connected to the coil+, so the ECU would draw enough power backward through the ballast to run even if the switch didn't provide power directly, so it wouldn't matter much whether it did or didn't. You don't need a starter relay to get cranking if you can feed enough current to the solenoid. A starter relay takes a small current (~1A) from the switch and then switches a lot more current (~20A) down into the solenoid; the solenoid engages the gears and switches on the main current (~200A) to the motor. While the stock ignition switch might put out enough current for awhile to run the solenoid directly, you're overloading it and its associated wiring very badly and it won't last long. The starter relay also sends 12V to the ballast on the coil+ side only when cranking and leaves that connection open at other times). The starter relay additionally serves as a safety feature via the neutral start switch (for automatic trans). Again, you don't absolutely need either feature to start. What you absolutely need to start is to provide power to both the ignition and to the solenoid in START and then power just to the ignition in ON. If you get cranking in ON, then either you've got the ignition switch broken in a funny way (very unlikely unless you've partially melted it) or you're feeding power the the solenoid some way you shouldn't. Before you go any farther, and after you get some good factory schematics (they're the very best investment you could make), I'd check for damage to the switch, switch connector, and especially the bulkhead feedthroughs. Look for melted and scorched plastic. Temporarially disconnect the wire to the solenoid and see that in ON you have power to the ignition and not the solenoid, and that you've got power to both in START.

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Author:	KBB_of_TMC [ Sat Feb 26, 2011 11:50 am ]
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I consulted my FSM from that vintage, and it clearly shows that in both RUN and START the ignition switch provides power to the ballast and ignition module; both for the standard and leanburn systems. It also shows the starter relay just like earlier models.

Author:	KBB_of_TMC [ Sat Feb 26, 2011 12:01 pm ]
Post subject:
I consulted my FSM from that vintage, and it clearly shows that in both RUN and START the ignition switch provides power to the ballast and ignition module; both for the standard and leanburn systems. It also shows the starter relay just like earlier models.

Author:	valiant effort [ Thu Mar 03, 2011 7:04 am ]
Post subject:	grey hair
For the record I cannot tell you how many times I have heard electricians and plumbers say " don't worry about how it looks the carpenters will fix it" lol...

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