How do you know if your ignition control module is bad?
 

Hello,
I am new on here and I was hoping to get some advice from you guys. I have a 1973 Ford F-100 that has an electronic ignition from a 1974 Ford F-100. How do I know if the ignition control module is bad, because when I try to start it, it turns over very slow. Sometimes when I try to start it turns over very fast and normally starts. Thanks for any advice in advance.

That's more of a battery and or starter issue.

Welcome to the site btw.

Welcome to the site! I'm new also. When my module went bad my truck wouldnt run at all. I bought a new one at advance auto parts for $21.

I doubt that it's an ignition problem. Like Montana_highboy said, it sounds more like a starter/battery problem.
Have the battery checked to make sure its good. If it is, the next thing to check are the battery cables, in particular the ground cables. Make sure you have a good ground directly to the engine block. Also make sure the cab and frame have good grounds also, this doesn't have anything to do with the starting problem but it will help avoid other pesky electrical problems down the road.
Clean and tighten all of the cable connections.
If there is still a problem, have the starter checked.

Thanks for making the point about the starter/battery. Since I got the truck, I have looked at the starter and it has a big dent in it. Would that affect why it isn't starting? I tried to start it the other day and it turned over ok and it sounded like it wanted to start, but it didn't. I am not sure if it is the battery because I bought it in February.

These old rides only need two things to run; spark & fuel. That's what I like aboutr them over the computer type sensor style rides of the 80's above.
The dent in the starter ; might effect it turning and was prolly cause by someone denting it to clear headers or the likes.
If the ignition module is bad or no contact with a ground cable it wouldn't turn over alick.
Oh;
Also "Welcome Aboard" as well. Best place to have a Ford Truck.

Mitch

I was thinking it might be the spark plugs because today I tried to start it and it was turning over real good and sounded like it wanted to start but it didn't. We checked to see if we were getting gas to the carburetor and it was. It was also getting gas to the engine as well. We checked the spark plug and spark plug wires and it wasn't getting spark, so we went to the auto parts store and got new spark plugs and put them in and then tried to start it and it did the exact same thing it did before, didn't start. I think it is demon posessed.

If you have a test light and a multimeter, there are tests that can be made - here's a link that might help:

https://www.ford-trucks.com/forums/8...-problems.html

Thank you Furyus1, I will check that out. I think that might be the problem!

Thank you everyone else for their very helpful information, y'all all contributed to what might be the main problem.

The three step scenario of a failing DuraSpark ignition module.

1) Module overheats, engine dies. Module cools down, engine re-starts almost at once.

2) Module overheats, engine dies. Module cools down, engine re-starts in an hour or so.

3) Sooner or later, usually sooner, the module overheats, burns out. Now the engine will not re-start.

Since these modules are notorious for failing when they overheat, taking it to an autoparts store to have it tested..usually does not work...because it's cool.

DuraSpark was introduced in 1974 on passenger cars/trucks. 1974: The module is the same for both, but it's 1974 only. 1975 is not the same.

D4AZ12A199C .. Ignition Module (Motorcraft DY157B)

Marked: D4AE-12A199-A1A or A1D, or A2C, or A2D.

So my truck won't turn over if the ignition module is bad, right?

Yes, the engine will crank, but whether it cranks slow or fast has nothing to do with the ignition module.

It may act that way due to a fully charged or low battery.

Replacing the spark plugs has nothing to do with the problem.

If you aren't getting any spark to the wires or plugs, it could be a faulty coil, ignition module, or?

I can tell you this, Ford mechanics once refered to DuraSpark as NeverSpark...because the modules used in 1974 (and 1975) were crap!

I installed the entire wire harness from a 75 truck into my 77 truck and had no spark. Turned out the modules are different so when I installed the 75 module, truck ran fine.
Might be something to check anyway? The grommets are color coded.

1974 is a one year only module: D4AZ12A199C.

1975 is a one year only module: D5AZ12A199C except on some early 1976 Bronco's which use this same module.

1976/79: Most cars/trucks use the same BLUE module (1U2Z12A199A replaced D9VZ12A199A).

1976/79: Some cars/trucks sold new in CA use a different RED module: D7AZ12A199A.

1978/79: Some cars/trucks use a BROWN module: D9AZ12A199C / 1979 LTD/Mercury Grand Marquis sold new in CA use: D9AZ12A199B.

Blue/Red/Brown: Above where the wires feed out of the module, is a colored plastic square.