I have replace nearly every part of my ignition system. I put in a new pickup coil, ignition coil, ignition module, and new ignition switch. It's still not getting enough fire, running at 4.9V run mode, it jumped up to 6.2 while trying to start the engine. It's not the ballast resistor because resistance is up to specs. I have no Idea what else it could be unless it's a bad wire from the ballast or module to the coil. If it is a bad wire I don't want to have to take the wiring apart. Is there a way I can bypass it? If there is anyone who can tell me what the problem might be, please share.

Sincerely,

Thea.

 

should usually be seeing higher voltage than that when cranking. when cranking the ballast is usually bypassed. have you checked to see if you are getting spark off the coil or at the plug wire?

 

Try jumping a wire across the ballast resistor and see what happens. If it works, replace it. If it still doesn't, that's one less thing to worry about.

 

Yes, I have and that's where the spark isn't happening. However, it's a brand new coil. I've done a resistance check on the coil itself and it's well within specs. A friend of mine, who is also a certified mechanic but retired, and I have narrowed it down to a possible wiring issue somewhere between the ignition module and the coil. There's a wiring connector that goes from the ballast to the coil; either the connector is dirty or it failed or the wire which runs to it or from it is burnt. I was trying to avoid having to unwrap all that wiring on the back firewall, but it looks like I'm going to have to anyway since I want my truck to start, and run, as well as get me from point "A" to point "B" and back.

One thing I do know is I have to renew the registration by the end of February. Can't renew it if it don't run as it will have to pass a mechanical inspection. I've been working on this truck for over 2 years now, and every time I get it to run, something else happens. It's been one disappointment after another with this truck, but I will not let it beat me. I will make it run, even if it take me till dooms day.

Thea

 

In the 50+ years I've worked on vehicles, I've seen a coil fail all of one time. I've put hotter ones on, but only one failed. If you have power to the coil, the failure is after that. An '85 will have either the basic ignition or the lean burn. I'll bet either your black/yellow wire is an issue or the brain box is faulty.

 

It's an 85 body but it has a 79 motor in it, so I believe the brain box is no longer on the truck because I've not seen one. Also, it has an electronic ignition, and the carburetor isn't original--it's older and not what should be on an 85. I've been digging into the wiring along the firewall, but the wire which goes to the coil, ignition relay, and ballast resistor is pink.

 

Electronic ignition was an option in 1972 and made standard across the board in '73 because it was so superior. Except for the lean burn system, all electronic ignitions are pretty much the same on Chryslers until 1988 when they went to fuel injection. You have a brain box somewhere. It's a flat metal box with a 5 prong plug on the top. One wire is often not used. It's often called the engine controller. As for the carburetor, there are a bunch that will work. As long as it bolts on and has enough flow, your carburetor should be fine. The thing about LA engines, another year of the same size will fit up to 1987. The 318 and 360 are balanced differently. Either one will bolt up to the transmission. Sakes, you can even drop a 440 in the truck because when it was designed, you could get a big block engine from the factory until 1978. Different transmission though.

 

if you think you have a wiring issue and don't want to deal with what is on the truck could buy a aftermarket harness. really sounds like you have already thrown everything else at it.
https://www.summitracing.com/parts/sum-851010

 

Hello ol' grouch,
Thanks for the information you have shared with me. It's helped a lot. It never occurred to me that there would be a brain box on any application before 1980. Anyway, I did a search for an 85 Dodge D150 brain box and I keep coming up with a bunch of different things, including ignition modules, which someone says is a brain box. I'm sure your not talking about an ignition module. However, I haven't a clue as to what one looks like, even by your description. I'm a hands on learner. Illustrations are great too.

Is this a brain box?

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From what you describe it sounds like you have the typical electronic ignition. There was two basic designs but both still need two inputs. Start and run witch should be battery volts. If you are not getting that in run or crank you have a problem Also inspect the ballast resistor and the terminals/wires going to it, They tend to heat up.