Testing DSII Module

Is there anyway to test a Duraspark II module to see if it is working? I am not sure if its the module or something else causing my problems.

read the section on mag pick up test. Mag pick fails much more frequently than the module.

http://www.1bad6t.com/Maverick/repair/duraspark.html

What are the symptoms? The only Duraspark module failure I've seen was heat related on a '77 module that came in my new '77 Bronco. The replacement made in '81 is still working well. The heat problem killed the ignition when the engine was warmed up. After a short cool down I had a spark until the heat killed it again. Are you not getting a spark at all? Or are you only getting a spark under certain circumstances?

The black wire in the mag pick-up is ground. it is connected to the distributor body and runs back into the module. Try checking continuity to the case. I have never checked. I will try to remember to check it when I get home today.

I've seen distributor bodies lose their ground bond to the engine block before. Probably too much mucky buildup inside the bore. Or rust.
Not sure if the modules ground through the body or not. If they did you would think that the ground symbol would show in the diagrams as was pointed out.
But then again, most of them do actually bolt to metal, so it's a very good possibility. I suppose one way of proving it would be to unbolt the module to see if it still runs. And if so, cut the ground wire to see if you still get spark.
This isn't for testing for spark in your case of course Tim. Just one way to put an otherwise perfectly good module in the scrap pile simply to test a vague theory.%)

Pretty sure (but not 100% sure) that I've seen some bolted to plastic and painted metal. I really can't remember though. And don't know what Ford vehicles might have had plastic panels in the engine compartment off the top of my head either. Maybe some cars? Or maybe it's just a false memory.

Because of the times I've seen poor grounding of the distributor body through the engine block, it was always my impression (assumption in other words) that the ground between the module and the distributor was a way for the module to provide a reliable ground for the distributor if needed. Rather than the other way 'round.
Or, similar to an alternator voltage regulator's tiny ground wire between the two components, merely a way for the two components to share the same ground potential.
In other words, a simple interconnect so they're on the same page, so to speak.
Not necessarily grounding one or the other to the rest of the system.

You've studied these things a lot jckkys. You know what all the ground wire does for the ignition?
Seems likely that it's a ground to the body, but not sure.
And it would seem like there would be a ground symbol in the diagrams if it was an absolute necessity.

Back to you Tim, you said you have original wiring? If so, can you verify good voltage to all the pertinent points? And still good even when you jiggle and flex the wires?
Igntion coil's +? Ignition module's Red wire? Or White wire depending on which diagram you read.
I know from testing a Blue grommet style module will provide spark no matter which wire gets switched power though. So as long as you have 12v to one of them and a good pulse from the distributor, a good module will give spark.

As suggested though, super easy to test the distributor's pickup with an ohm-meter. Would be a first check in most books anyway.

Good luck.

Paul

Hmm. If you don't mind having to reset timing after the test, one way to determine if the module is good (but only after you've verified that the trigger is good) would be to line turn the motor until the reluctor wheel's "spoke" is pointed right at the magnetic pickup. Then, with the distributor's hold down bolt loose and the key in the RUN position, twist the distributor back and forth so the spoke passes and re-passes the pickup.
Each time you do this you should hear a spark if all the parts are good.

I'm not sure how to otherwise provide a pulsed signal of the right type to trick the module into firing the coil. But in theory this should work.
Assuming all the other stuff tests out good.

You can verify the coil is working by doing somewhat the same thing. With power applied to the Positive side of the coil, intermittently apply ground to the Negative side of the coil.
Each time you touch and release ground, you will get a healthy spark if the coil is functioning.

Paul

While describing the method for setting the timing, you remind me that even if the distributor is not itself completing the circuit, the hold down and bolt should. But a continuity check of the distributor housing to the battery ground post should verify this. The output of the pickup coil can be checked with an analog volt meter by spinning the shaft with the orange and purple wires connected to the volt meter. The tiny pulses just barely move the needle, but they will with a good pickup. Poor connections often fail to transmit these pulses. So check your wiring. Ford never had a way to check the module except by substitution. What is the make of your module? After market modules are usually made in China. This is the source of nearly all the problems with "Duraspark" modules. New US made Motorcraft modules are still available. The DY-184, DY-683, and DY-893 are all US made interchangeable Motorcraft modules for the Duraspark II ignition. RockAuto. Jeg's, and Summit all have the DY-893. Get one one of these and you have both a backup and a substitute for diagnoses purposes.

And speaking of modules... Was at "NOS Only" today (be a great place to browse if you could just wander around) and was checking out the Duraspark modules he had in stock.
Oddly enough, the four boxes I opened happened to have some of the often harder to find versions. There was a Brown, a Green, a Black, and even the odd double-Yellow module.

And of course, the ever popular "US melting-pot" version...

Guessing someone returned a bad one and forgot to let him know.

Picked up a theoretically US made OE starter relay and an under-hood lamp for my '79.
Disappointed that I didn't read the label on the relay box when I saw that it was a Motorcraft red box instead of a Blue Ford box though. "Recommended by Ford. Made in China" right on the bottom of the box. Oh well...

Still a good day.

Paul

bad coil?

I checked my black tab 1974 module and the black wire grounds to both the module case and the ground tab in the distributer on the stator pick-up. I have a blue tab module and the black wire grounds to the distributer on the stator pick-up and a very high resistant ground to the module case.