ignition control module issues

[wilsbronco]

I am hoping someone can help me out. My bronco had some wiring issues ... windshield leaked, po had higher rated fuses than should have been in the panel, smoke, melted insulation, etc. I have rewired the affected circuits, which were primarily various lights, and got the windshield sealed. Now after working for a few days, it won't start. It's getting gas, starter turns strong, good battery, but no spark at the coil. I went through the tests in haynes and tested various things from the evt manual. Here's where things stand.

It's an 81, but has had the engine replaced with a fuel injected model, guessing 86 era based on what parts I find as matches when replacing. First, I accidentally broke the metal plug off the coil so replaced it even though the tests showed it was okay. I started with a spark tester and got nothing at the plugs, so I attached it to coil and no spark there either. The lightbulb test at the coil shows voltage, but no pulsing. So I moved up to the ignition control module (distributor mounted). According to Haynes, on pin 2 I should get somewhere near 12v when the key is in the "run" position. I get nothing. Now the wire goes to this rubber blob that has 1 green wire coming from the inside (ignition switch?) that gets split inside the rubber blob with a green wire going to the (-) of the ignition coil and the 2 pin of the control module connection. At the coil, I get the 12v, but not at pin 2. What is this rubber thing?? Is there a diode hiding in there or is it simply a splitter that's malfunctioning?

A brief history that may be applicable: ignition switch didn't talk to the fuel pump when I bought the bronco. Pump is now wired to a separate switch. With all my wiring issues, I have a feeling that the ignition switch isn't talking to the ignition control module and that's causing my problems (NOT a bad module). Before I cut the rubber blob out of the circuit, I wanted to make sure of what was going on. I'd live with wiring to another switch if that'd fix it.

Thanks

 

[Seabronc]

I suggest you get a meter not a test light when troubleshooting at this level. Knowing the actual voltage level is sometimes critical to figuring out the actual problem.

The line you are looking at is for the TAC. To get spark, you need 12V at the coil + and at TFI module via the white wire with a light blue hash mark on it. Sounds like you already have an EVTM, check that circuit out including the run to the EEC.

Attached is the EVTM diagram an 85. With an EEC circuit,

Good luck,

>-

 

[wilsbronco]

I have a good meter and was using it primarily. I just used the light to see if it was pulsing (books suggested the light for this). Thanks for those pages. I do have an EVTM, but it's for an 81 so doesn't always mesh with what is actually in my bronco.

 

[Yardape]

So is the whole efi setup in the Bronco or are you running a carb? Are you using the Dizz from the furl injection?

 

[Yardape]

So is the whole efi setup in the Bronco or are you running a carb? Are you using the Dizz from the fuel injection?

 

[wilsbronco]

So is the whole efi setup in the Bronco or are you running a carb? Are you using the Dizz from the furl injection?

No carb, everything looks to be around 86 era fuel injected (it's the way I bought it, not real sure of the history or specifics) with it being fairly complete as far as what they swapped out, although the wiring is completely spaghetti with LOTS of connectors just hanging loose. They probably added the necessary "new" stuff and left the old as well. My guess at 86ish is because I end up having to bring the old part in to get a new one and the ones that match seem to be for that range of years. For the ICM, according to the pictures in Haynes, it matches the TFI-IV ICM. My gut tells me it's probably wiring or the ignition switch based on other issues I've had, but I guess I'll take the ICM off next to take resistance measurements. If it's as big a pain as it looks, I might go ahead and replace it while I have it off as it's not too expensive and then I've got a known good. Just wish I knew what that rubber thing was that the wire going to the 2 pin and the (-) coil was running through. It'd be much simpler to cut and fix that ... Haynes says I should have 90% of battery at pin 2 with ignition switch in "run". I get 0. The other wire coming out of the rubber blob has 12v. Not sure if it matters, but the Tachometer has not worked since I bought it, is the gauge the one the diagrams are referring to that the coil (-) and ICM pin 2 go to? Also, according to the diagram, S170 shows up as a splice or crimp terminal ... is that my rubber blob? Could I just cut the wires and redo the splice?

 

[Yardape]

Has this truck ever ran with this setup? If I were in the same situation I would go to the auto wreckers and remove the complete wiring harness. That way you can see how its supposed to be hooked up. Any parts you need identified if you could take a picture and post it on here would greatly help us identify it for you. Trying to invision what you are taking about by saying rubber blob is kind of difficult

 

[wilsbronco]

Has this truck ever ran with this setup? If I were in the same situation I would go to the auto wreckers and remove the complete wiring harness. That way you can see how its supposed to be hooked up. Any parts you need identified if you could take a picture and post it on here would greatly help us identify it for you. Trying to invision what you are taking about by saying rubber blob is kind of difficult

It's ran for several years with this setup. The problem is very recent, right after the windshield leaked causing electrical shorts around the dash and fuse panel. It ran for about a week after fixing the other electrical issues, although was stubborn about starting on a couple occasions during that week.

I unplugged the connector from the ICM so that I could take the picture. The single wire coming into it from the right goes back into the wire harness and goes towards the dash area. The two wires coming out the other end go to the coil (there were a couple of bare spots on that wire, so I replaced and have confirmed continuity to the coil) and to pin 2 of the ICM connector. the wire to the coil has 12v, the wire to pin 2 has 0. I'm just trying to figure out if that rubber piece has a diode inside it, or if it's just a splice that has somehow gone bad.

 

[wilsbronco]

I still don't know what was inside the rubber splice piece, but I cut it out and spliced the 3 wires together and it fired right up. I will take the piece to the autoparts place, and if they can't identify it, the dealer to see if it is important enough for me to get another one and put back in.

 

[wilsbronco]

So much for that "fix". It did great all day Friday, started and stopped several times. Saturday it started acting up with symptoms similar to the pickup coil going out ... i.e. turning itself off but starting back up after it cooled a bit. First time, it started back up about 5 minutes later. It took a little longer the next time, and the last time ... well, she never started back up. Towed it back home this morning and tried all the tests again today. People keep telling me that the fact that it came with it's own towbar when I bought it probably was a clue ...

Once again, no spark at coil. So the flaps had a pickup coil in stock, hopefully a match, that I picked up late this afternoon. After cutting a storm damaged tree down and having it hit the electric line to the house on the way down (wasn't exactly the planned direction of descent), I wasn't really in the mood to fight with the bronco too so gave up rather quickly when I couldn't easily get the old part off. I will tackle it again tomorrow, but are there any words of advice on removing the old pickup? Haynes is lacking in specifics.