Alright I replaced the ignition switch, with no avail. Still getting code 212. The problem is so intermittent, I wish I could get it into its stalled in a controlled environment, so I could test and see what the issue is.

I have done some reading and from what I understand, the EEC is responsible for advancing ignition timing, and the diagnostic signal for the ignition system. Please correct me if I am wrong. I am tempted to blame the EEC on this one but it is generating a trouble code and recognizing there is a fault. Although this code isn't super helpful, even if the spout circuit is grounded it seems like it would still be able to run. Only reason I say this, is disconnecting the spout from the module reverts it back to base timing. I bought a "new" EEC, I am going to install tomorrow to rule out the computer.

Another thing I am thinking is maybe its a faulty relay to the EEC itself, I am going to unplug the relay for the EEC and see if the instruments are coming on, if they are then my guess is it is a faulty relay or some kind of problem with the EEC getting power. That's plan b, and an easy thing to check off the list.

It also displayed similar symptoms when the PIP was failing or dead. I have had it in a fault state before but not recently, and the new PIP was sending out voltage.

I have ohmed out the ICM several times, I even threw it in the oven and ohmed it out, it has tested good every single time.

I have ohmed out and checked all the connections in this ignition system they all check out.

 

Not completely correct. The Ignition Diagnostic Monitor (IDM) signal is generated by the Ignition Control Module (ICM) on 1994 and later trucks. 1993 and older the IDM is derived from the negative side of the coil. That IDM signal is an input to the computer (PCM). The computer does control the timing (advance, retard, dwell) when the SPOUT plug is in.

I do agree the code is just the computer sensing a problem based on the IDM signal. It knows it sent out a pulse string, something is dropped out so Code 212 is flagged.

 

The IDM and the ignition switch have little to do with one another in reference to your 212 code
The IDM is just what it says, a monitor
The stator in the distributor and the TFI module are the normal culprits
After replacing both if those, inspect your processor

 

Thank you guys for the insight.

Code 212 is just saying that the signal, or the IDM, from the negative side of the coil isn't or there is something wrong.

I swapped in the other EEC I ordered and some very weird things happened, as soon as I plugged it in and started it, it was surging like crazy and then it would die, it repeated this a couple of times until it mellowed out at 1000 rpms. But it would die upon giving it gas. I tried to pull codes off of it but it wouldn't flash the check engine light, so my guess is I got a defective computer.

Got home and swapped the old eec out and didn't make it 200 feet before it stalled. It stalled 4 times just going around the block, I let it run in the driveway and then it stalled in the driveway. Luckily I am now able to probe everything. Here's what I found: The signal from the pip to the was around 4V AC which it should be between 3 and 8.5 so it checks out. I measured for the presence of the spout and that was at 4.5v AC its supposed to be between 3 and 8.5 as well. There is nothing at the coil negative and nothing getting to the computer, and the tach is dead. It sounds like there is an issue with the ICM but I have gone through several of them and it can't cure it.

I have absolutely no idea what the issue is. I am tempted to say its the EEC, but its generating a spout signal. Is it possible to still failing and be generating the voltage to the ICM?

Thanks again for everyones help.

 

Yes to both.


Agreed, you got a door stop not a working PCM.


Cannot cure what? No spark issue?


You have a PIP pulse train and a SPOUT signal from the computer to the ICM, but no spark. If you have +12 VDC at the top side of the coil and no pulses to ground on the negative side, you have a defective ICM or open circuit between the ICM and coil. If there is a pulsing circuit to ground then you most likely have a bad coil.

To be honest using a DVM to check the PIP and SPOUT signal is better than nothing, but it's like taking a knife to a gun fight. One of those cheapie o-scopes we have seen on this forum would come in very handy here.

 

Lol the new computer is a joke, I don't even know how they can sell stuff like this.

The previous ICM didn't cure the no spark issue.

The coil is getting +12v. I will get a test light and hook it up to the negative side of the coil. To see if it is pulsing.

I will look into getting one, no one has them nearby so I will look into the best one that can get here asap.

 

Ok I have no idea what is going on. I let the truck sit for 4-5 hours and then started it back up and no issues at all. Took it for a drive and absolutely no issues. I let her idle in the driveway and she idled great. Whatever this issue is, it has now become even more illusive. I am starting to think its a ghost in the wiring. I am going to pull codes and see if anything else comes up that might give us a clue.

 

Alright still getting code 212, nothing else. Went and took the truck for a short drive and she stalled again.

I put in a motorcraft ICM when I overhauled the ignition system, its gray but I am questioning its integrity or if it is secretly a "black" one used on the later years. Is there any way to bench test it to make sure it is a push start? Also how is it possible that they become damaged? It may be possible that it is already broken. I have used the bench test as specified in the haynes manual several times, which is just measuring resistance values of the ICM itself, even putting it in the oven to recreate engine bay conditions.

I completely pulled the harness apart and there is no opens anywhere for the ICM to coil, or coil to EEC. Its really starting to sound the ICM is the culprit here.

 

Replace the module with a black one
Retest for the code

 

I know you said you pulled the harness apart. How's the wiring that's wrapped in the shielding? https://www.fullsizebronco.com/threa...n-wire.210961/ Check out post 4 at this thread.

 

Alright spent about 3 hours troubleshooting this issue. Here's what I found.

The IDM voltage or the coil negative that gets switched on and off for spark to the coil is the issue here. I didn't get an o-scope here in time so I improvised with a testing light. In the stalled state this open to ground or switch essentially isn't opening but upon switching the ignition switch on and off it fires just fine until it stalls again. When it cranks the light flashes indicating the IDM is opening and closing the circuit, when it starts the light is just always on, this is when having an o-scope would be vital.

I also used a timing light and spark tester, it would abruptly shut off when stalling, when it would crank before resetting the switch there was no spark just another way to verify the IDM was not opening and closing coil negative.

Another interesting thing is the fault condition didn't exist when the spout was out. I initially thought the computer may have something to do with this or may be advancing or retarding the spark to a point where it would stall, but this isn't happening. Unless the computer is commanding the TFI to stop firing, which I would believe to be an absence of the spout signal, which cannot happen because the TFI would revert to base timing which is 10*. So I don't think the computer is at fault.

I am going to try a new TFI as it seems like this is the culprit.

Hope everyone can follow what I'm saying. Thanks for everyones help and input.

 

Alright tried yet another TFI module, still stalling.

I just put an o-scope on order it will be here tomorrow morning.

I am wondering if there is a good way to test the hall effect sensor. I know using a dmm isn't the most accurate way of doing it. According to the haynes manual the sensor should be outputting 3-8.5V AC, its outputting around 4.5v AC. Even when the truck is stalled and won't start back up again, it is still outputting voltage.

I am thinking that the computer is to blame as it doesn't stall with the spout connector out. But again I can't see what the computer is telling it to do without an o-scope. I am hesitant to order another computer online since the last one I got isn't functional. Does anyone know of a reputable place to get one?

 

It is all intact, there isn't anything wrong with the harness. I wish it was as simple as the harness though.

 

Classic symptom of a failing computer or the SPOUT signal is getting grounded between the computer and ICM. I believe there was mention of checking the wires that run inside the shield for signs of chafing.[/QUOTE]



I do not recall which brand you used for the other replacement computer. I would stay away from any Cardone brand.

 

I have pulled the harness apart and checked for chaffing of the wires, all the wires are intact.

I used Blue Streak Electronics. Awesome, I was looking into Cardone, will steer clear, thank you so much.