I'm posting this in the hopes that someone benefits. I maybe wrong about something so I encourage and welcome corrections and feedback.
First, hit the over 216 manuals thread and study. I mean really study. Its by far the most valuable resource you have at your disposal.
Second, the haynes manual is trash for figuring out how to wire the ballast resistor. There are some good things to be found in the Haynes manual, but the inconsistencies, lack of necessary information and the fact that a power lock circuit wiring diagram was included while an ignition circuit diagram was not, make it usable as little more than a great way to familiarize oneself with the basics.
The best part of the haynes manual is the fact that all engines are covered, save the astron 2.0, 4g52.
I can't say for certain that this information will be true for those who do not own a g54b. My experience with my 88 led me to the electrical systems service manual from 87 for the montero found in the 216 manuals section. Meep that in mind
In another post someone stated that that MSD Blaster coils are all internally resisted. This is simply not true. I picked up a blaster 2 from a rampage at the junkyard for 10 bucks. It was a P/N 8202. 8203 has an internal ballast resistor. 8202 does not and MSD says to install a 0.8 ohm resistor or resistor wiring when using with a point style setup. The stock/ oem ballast resistor in the truck is 1.1 -1.45. Most measure around 1.35. I Dont have a points style ignition and when the 0.8 ohm resistor cracked i swapped in a stock one and it runs fine. It also ran fine with no resistor until it burned out the little back half-moon on the advance plate inside the distributor. Multiple sources call it different things and it is in reality a combo of them all. It is the pickup coil/igniter/ICM all in one. Don't let them confuse you. If you don't have a resistor I'll wager that you'll burn up multiple of these up many times before the coil suffers any real damage.
If the resistor has only cracked wrap some electrical tape around it and order a new one. Keep driving to a minimum and you should be able to make it to the store and back.
The #1 thing to keep in mind: The ballast resistors are old and porcelain. They are FRAGILE. To remove the presumably 8mm nut on either post make sure you use a second wrench to hold the 2nd nut of the same post or you will crack and break it before you ever get the wire you want. Its very easy to go from excited to install a new coil to frustrated that you now need a part most stores don't carry and you may not be able to drive without.
If you want to preserve your coil, ballast resistor and distributor components, when not running, off or acc are the only places the key should rest. Anything past ACC while the engine is not running will cause the resistor and coil to get very hot and potentially fail.
The way the ballast resistor and coil are wired is simple enough.
There are 2 12v wires coming from the ignition switch. 1 is B&W, the other Black and Red. They hook up to different ends of the resistor. The B&R usually has a female connector and slips onto a male tab connected to one of the posts on the resistor. If you want, you can do away with the tabs and attach it with a ring connector.
99% OF THE TIME IN THESE TRUCKS B&W IS SWITCHED 12V. This should be the case here. The B&R wire only receives power when the key is moved to START. Because the coil needs more power during starting the resistor is bypassed.
FROM THE SAME SIDE OF THE RESISTOR AS THE B&R 12v connect a wire to the coil (+). This allows power to flow directly into the primary winding of the coil unimpeded during only the starting process.
FROM THE SAME SIDE OF THE RESISTOR AS THE B&W 12v connect the B&W wire from the distributor. When the key has been moved back from START to RUN/ON, the B&R 12v is a dead wire. The path of energy to the coil now travels from the B&W THROUGH THE BALLAST RESISTOR and into the coil.
The blue wire from the distributor connects to the (-) terminal of the coil and is involved in signaling the coil to fire. This comes from the 12v supplied to the pickup coil/igniter/ICM via the B&W wire of the distributor. As the signal rotor/reluctor moves it makes and breaks the connection and this is what dictates when the signal to fire is sent by the blue wire to the coil. The coil then discharges via the secondary winding and sends high voltage blasts to the distributor.
There are 2 other things that get wired in as well.
1 is a tiny black noise suppressor to help the radio not pickup the magnetic field generated by the ignition system.. It has a blue wire that also goes to the coil (-) and a black wire that clips it into a series of other clips and grounds. This is not needed to start or run.
The second thing is an inductive filter which is necessary for the tachometer to work but not necessary for the engine to start or run. It connects to the coil (-) and has a second wire with a clip.
The MSD BLASTER 2 8202 should not need the ballast resistor to run. Not because it has an internal ballast resistor (again it doesn't 8203 does), but because most of these trucks use basic and early but still electronic distributors and not points. The MSD may not like the trucks stock resistor.
If you want to do away with the resistor just run the B&W 12v to the coil (+) and the B&W dizzy wire to the same post. The B&W is switched and has power both in the run and start positions. The B&R can be cut, shrink wrapped, and tucked away.
I hope this helps at least 1 person because wiring this thing was a nightmare to understand at 1st mostly because I didn't understand the flow of energy that was meant to be achieved. Just keep the notion in your mind that only one wire is actually sending power THROUGH that resistor and its the B&W 12v from the ignition switch, and only one wire makes use of that modified voltage and its the subsequent wire on the other end of the resistor going to the coil (+)
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Originally Posted by oldirtywizard
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