Instead of reviving a 2 year old post, I thought it better to start afresh with the current problems. I had a GM HEI icm wired up in my '85 Bronco and had nothing but headaches. I was fortunate enough to find all of my old DSII (plugs and all) stuff to wire it all back together. I have no spark. I am fortunate enough however to have an '86 Bronco sitting right next to it that runs well.
I rewired all of the factory plugs back into the harness and was very careful about my connections, and used heatshrink over every one. I have checked the icm to see if it's good by installing it on the '86, as the plug into the box itself is blue on each. I also feel that I should mention that the distributor is brand new and the coil is good as well, I have a couple spares too. I then triple checked every wire to see if they were all correct. All good there, so I grabbed my trusty 12v test light and checked to see what I had on all the wires on the running truck and made a written list of everything. I then did the same on the non-running truck, then compared them for inconsistencies.

Here is what I found: On the good system, the purple wire coming out of the box showed me nothing on crank or run, but on the non-running system I have hot on crank and run.

The green wire coming out of the box on the good system showed flash at crank and extermely dim in the run position of the key, but shows nice and bright solid hot in the crank and run postion of the key.

On the white wire with the red stripe that plugs into the red and white wired plug of the box, truck side of the plug, the good system showed that I should have power on crank, but I have nothing on the same wire in the bad system.

Now let's move on to the truck harness, the one with the fat red wire with the green stripe. That wire on the good system shows hot, but dim, where on the bad system it's bright hot and only dims slightly with battery draw.

In that same "cluster" of wires going into that plug There is are two wires acting exactly the same-white with a red stripe and red with a white stripe. On the good sytem It stays on bright for a couple secs then starts blinking in the crank position, just blinks in the run position. All it does on the bad system is blink in both positions, maybe dimming slightly with battery draw.

I know this has been a very long post, sorry, but I am trying to be most informative. I have a cheapo multimeter, but I don't really know enough to use it confidently. If you have any ideas or questions, please post up! Thanks

 

I will take a stab at this…..

Purple wire first… the dist has 3 wires, black which is sole ground for the ignition system and 2 other color wires (purple & orange maybe?). The distributor generates a very small and mostly unmeasurable AC signal which travels down the purple & and orange wires to the DS2 ignition module. I do not believe there should be 12 volt on the purple wire. This should be the first thing to check out and mostly why it does not work.

The green wire coming out of the box on the good system showed flash at crank and extremely dim in the run position of the key,…. This is normal … see note 1 below.

but shows nice and bright solid hot in the crank and run position of the key. This is not normal so I am assuming this is the non-running system.

Regarding the 2 wire power plug on the DS2 module. At this point, just make sure the RED wire that goes to into the DS2 module has power in both run and crank key positions. Stab the wire with a pin a few inches from the blue plastic grommet and use your test light.

Now let's move on to the truck harness, the one with the fat red wire with the green stripe. That wire on the good system shows hot, but dim, where on the bad system it's bright hot and only dims slightly with battery draw. This is normal for the good system and also proves the bad system has NO current flow through the primary of the coil.

Note 1 = Not all DS2 ign module work the same. Some cheap aftermarket ones will not conduct current through the coil primary with the key ON and not running. An original Motorcraft will work as you describe and conduct current with the key ON.

Are both the ignition modules the same?

Jim

 

Hi Jim- I appreciate your trying this for me! It seems both you and Franklin2 are the biggest help on my ignition troubles.

The purple wire I knew to be way wrong, I can't see how or why that would have power!
The green wire I also knew to be way wrong, also a concern.
The red wire does have hot on both run and crank.
Shouldn't that fat red wire be a touch dim on the bad system in the crank position due to the involvement of the ballast resistor wire?
Yes, both ICM boxes are identical on both trucks, not Motorcraft, but I believe them to be the same brand.
I'll try the other coil today and try to chase down why I have power on that purple wire today. I know that's wrong as I have replaced enough pick up coils in the dizzy to understand how that works.
Thanks again.

 

The non-dimming test light could be caused by a resistor bypass wire which was added with the 85-86 TFI ignition or…
<O</O
Another reason for not dimming of the test light downstream of the resistor wire is because there is no enough current flow through the circuit other than what your test light draws. If your test light has a small bulb you would not notice any dimming. If you used a large current draw bulb, like a brake light bulb, you would see that it is dimming more than if the test light was across the battery terminals.
<O</O
On the good system, with the key ON there is current flow through the resistor wire, coil primary and out the coil negative to the DS2 module then out the DS2 module via the black wire to ground in the dist. On the good system the bulb gets dimmer the closer you get to ground which verifies the circuit is complete.
<O</O
On the non-working system, if you add a ground the coil negative with the test light in place you might see the same dimming of the bulb as on the running system.
<O</O
Bottom line is if you have power to the coil positive with the key ON/Cranking… press on… to see why the DS2 module is not opening and closing the circuit which would cause the test light to flash when connected to the coil negative.
Jim<O</O

 

So I guess the first thing to do would be to find out why my purple wire is hot, maybe even explaining why it is making the green coil wire solid hot. Just got home, I'll go see what I can figure out. Thanks, I'll post back.

 

I haven't been following this too closely(Jim's been doing fine ) but if you think about it, what's common between the DSII and the hybrid ignition you had before (that was supposed to work) but didn't? The distributor is one common piece correct? Both didn't work, so the problem must be a common piece between the two.

 

I would like to start out by publicly declaring that I am a *******. Sadly enough, it took a close friend who is a chevy guy to find it. Franklin2- the GM HEI did work, it just never ran as good as I thought it should. So here was my mistake: I cut the plug off of an old DSII box to plug into my truck's ignition system, and wired the four wires to the GM module. I forgot that I had to change one wire in that plug. The DSII plug has purple, green, orange and black wires coming off of it. The GM module takes purple, green, orange and red. I had 12v hot wired into where the ground is suppsed to be on the DSII system! What an idiot I am! My face is red and I feel bad for wasting you guys' time. As usual though, the guys on this site immediately rose to the occasion tho help.


THANK YOU!!!!!
P. S. and by the way- when I switched the wires to the way they should be, it fired immediately and purred at about 600rpm. No odd missing sound like it had with the other module. Lesson learned. I have driven it approx. 50 miles this evening, highway and city and I am very happy. It hasn't ran this good in over 2 years!