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Discussion Starter · #1 ·
Had a no-start issue last year, replaced all the ignition stuff (except wires which weren't that old), TFI, whole dist (which has PIP in it), coil. Issues went away.

This year the no-start is happening again. Very random, spins fine, will not fire up. Happens cold or hot. Never while driving, only at idle or starting.

Pulled the codes and all I get is a 212 (IDM), which is probably due to incorrect TFI... but that shouldn't cause a no start (and more on this later).

So for the past few weeks it has been happening again, totally random. I went ahead and replaced the wires and TFI, and while it ran better, the random no-start continued.

Today it happened and I actually had the tools and manual to get more data. On the no-start there was no spark verified. I plugged in an extra brand new TFI module and it still didn't start (totally eliminated the TFI as a problem...FINALLY).

I pulled the steering column trim off and pulled the ignition switch module, replaced it with a new one and it started right up.

BUT THEN I put the old one back on and... yes, it started right up. There doesn't look like there are any issues with the wiring close to the switch, and the old one doesn't rattle or anything (although I will open it up and see if there are possible broken contacts or something...).

Any ideas??? This random $hit is annoying.
 

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Satyr of the Midwest
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Read this TSB first:



After that, I'd look for loose connectors, bad wiring, etc.
 

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Discussion Starter · #3 ·
Read this TSB first:



After that, I'd look for loose connectors, bad wiring, etc.
Yep, did that one a month ago. Was completely expecting to find the problem, and instead I found some perfect wire harnesses. Mine by the way (94 model) does NOT have that damn resistor. Looked everywhere for it.

I also verified an excellent connection between the harness and the computer, which was a relief... except that I still have the no-start issue.
 

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Satyr of the Midwest
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Mine by the way (94 model) does NOT have that damn resistor. Looked everywhere for it.
Of course. You have a CCD ignition setup. Pin #3 of the TFI ignition module goes directly to the #4 pin of the PCM, to provide the IDM signal. The 22k resistor is only on TFI systems with a gray ignition module. If you had one, it'd be in the large harness between the driver's side fender liner and the front driver's side of the engine, right behind the a/c compressor. Those with 1994-1996 trucks shouldn't have the IDM resistor, and should always have a black ignition module. A good thing to keep in mind when you go to the parts store for a replacement: ask for the ignition module for a 1995 Ford Mustang GT. You'll get the right one every time.


Anyhow... :toothless I think you might have a bad PIP if everything else is testing good, but continue testing! The ignition coil connection must be good, and battery voltage should exist on the positive side of the harness connector with the key ON. Same for the distributor's harness connector, in that there must be battery voltage at the appropriate terminals. Ditto for the ignition module. Check out the Haynes or Fireguy's website for the pinouts.
 

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Discussion Starter · #6 ·
Good info thanks...

I spent enough time to irritate the Napa counter guy trying to find the TFI that was black. Finally just bought the oem one that was twice the price, and when it got there... yep, grey. Wish I had known the Mustang Crossover part.

I'm leaning toward PIP as well, since that's what it was last year. Although, why would it crap out in only one year, and why isn't it throwing a code?


Of course. You have a CCD ignition setup. Pin #3 of the TFI ignition module goes directly to the #4 pin of the PCM, to provide the IDM signal. The 22k resistor is only on TFI systems with a gray ignition module. If you had one, it'd be in the large harness between the driver's side fender liner and the front driver's side of the engine, right behind the a/c compressor. Those with 1994-1996 trucks shouldn't have the IDM resistor, and should always have a black ignition module. A good thing to keep in mind when you go to the parts store for a replacement: ask for the ignition module for a 1995 Ford Mustang GT. You'll get the right one every time.


Anyhow... :toothless I think you might have a bad PIP if everything else is testing good, but continue testing! The ignition coil connection must be good, and battery voltage should exist on the positive side of the harness connector with the key ON. Same for the distributor's harness connector, in that there must be battery voltage at the appropriate terminals. Ditto for the ignition module. Check out the Haynes or Fireguy's website for the pinouts.
 

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Satyr of the Midwest
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Intermittent faults are always a bitch, especially in the higher signal rate stuff. The PCM will only store a trouble code if the fault is "intermittent but consistently screwed-up enough," if that makes sense. In other words, it'll be monitoring the PIP's waveform, and determine whether the signal has some erratic (non-square) quality to it. Having a non-existent signal is different, because the only thing the PCM will be thinking is, "the engine isn't turning, so I'm not going to fire the fuel injection OR the ignition coil."
 

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Discussion Starter · #8 ·
Excellent explanation. One thing is the code, but the other is the parameters where the code is created.

I need another no-start to happen, and I need to check the PIP directly. The ignition switch, TIF, coil, wires, cap/rotor are out of the picture.

It's also interesting to note that when the no-start happens, there seems to be a set number of tries before it fires up again. I don't think it's time related and it's definitely not temperature related.



Intermittent faults are always a bitch, especially in the higher signal rate stuff. The PCM will only store a trouble code if the fault is "intermittent but consistently screwed-up enough," if that makes sense. In other words, it'll be monitoring the PIP's waveform, and determine whether the signal has some erratic (non-square) quality to it. Having a non-existent signal is different, because the only thing the PCM will be thinking is, "the engine isn't turning, so I'm not going to fire the fuel injection OR the ignition coil."
 

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Discussion Starter · #9 ·
I don't recall the numbers, but I checked it twice under no-start condition and it was on the higher end of the spec so all good there.

I was worrying that my fuel pumps were going out, especially in the TX heat. With the pressure I'm getting I doubt it... unless pump failure doesn't show lower fuel pressure before their demise...


What's your fuel pressure when it won't start?
 

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Satyr of the Midwest
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Another good indicator of PIP signal or not: watch your tachometer. If it's above zero during cranking, you're getting a PIP.
 

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Discussion Starter · #12 ·
Ok couple of weeks later and the no start pops up again...
This time I watched the tach, and no signal... so it's PIP.

Pulled the distributor (almost exactly 1 year old...) replaced it and all seems good. Since every other ignition part is replaced, and the Tach showed no signal during the no start, I think it's pretty conclusive.

Thanks for all the great input.
 
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