My truck has been through three ignition modules (EDIT: I meant ENGINE CONTROL MODULE), all failed with the EXACT same problem. 1989 F350 crew cab, 351, manual.

When warming up there are three engine running modes. Full choke, partial choke, and run. These are no doubt called something else in EFI land. In full choke mode everything runs as expected. It unfortunately doesn't stay this way very long as the engine heats up, usually about a quarter mile from the house. You can tell right away when it falls out of this mode because the idle speed will drop AND the real fun starts when you try to pull away from a stop. The engine flat dies. I have to stomp on it, start and it wheezes and gasps until if finally starts up. If left alone it will idle through this stage. If you slowly accelerate it will also slowly accelerate. If you step on it, it dies immediate, prompting another flooring it while starting. This phase lasts for a good 3-4 minutes. Once it's past this phase it runs perfectly.

First time I fixed it by getting a new ICM. Worked like a champ. Second time I fixed it by getting a new ICM. This is now the third time it's doing it and at $300 a whack these are just getting too expensive to swap out every couple years. These units only have one electrolytic cap so I was debating to try a cap replacement on one of my non-functioning spares.

I also thought maybe the shear physical movement of unplugging and plugging in the units cleaned up the contacts, so yesterday I went out with electrical contact cleaner, a nice soft brass wire brush, and gave the boy and girl end of the ICM a good scrub down. Didn't help.

If I get another ICM then I'll have put more money into this truck than it's worth. Welcome to the club I guess.

I hate to do this again when the likelihood this exact problem would simply break yet another ICM. I will add the truck at various times developed a cab leak that when unused can greatly increase the humidity in the cab. This has hopefully finally been resolved. There was no coincidence between cab humidity and ICM failure.

Are there any suggests out there? Is there a way to officially diagnose and fix the older ICM's? Is there a way to officially replace these $300 ICM's with something more cost effective?

 

The very first time this happened I took it to my mechanic. He officially said, "I have no idea what is wrong." He is quite competent and has done a lot of other work on my Ford motorhome with exceptional results. He has also worked on this truck when it was running with exceptional results. When he gave up on it I swapped the ICM the first time which fixed the problem.

 

Where are you buying these expensive ignition modules, Ben Dover Auto Parts?

1U2Z-12A199-AA (replaced D6AZ-12A199-A & B; D9VZ-12A199-A) .. Ignition Module - blue plastic square (Motorcraft DY-893) / Available from Ford

The remote mounted modules have a colored plastic square used to ID them. This is the most common of all the modules.

MSRP: $61.93 // If bought from autonationfordwhitebearlake.com (MN), the discounted price is: $37.47!

Applications: 1976/89 myriad FoMoCo vehicles.

Parts catalog pic: Look at D9VZ-12A199-A for the 1980/89 applications for this puppy.

 

I went off the original part numbers, E9TF-12A650-AE1A. I may be using the terms incorrectly. This is the main brain under the dash.

 

Looks like I meant ENGINE CONTROL MODULE.

 

Always read codes and diagnose before changing anything.


3 failures with exactly the same symptoms means you are changing the wrong part. I know you think it was fixed each time, but all that is proven is that the problem is intermittent.

So, the fault is not the ECM.

Once again, read the codes first, but I would not be surprised to find a faulty ECT or IAT sensor.

 

No part numbers marked on parts after 1956, just casting or ID engineering numbers, when applicable.

I looked this puppy up in the 1980/89 Ford truck parts catalog recently, but I don't recall for who.

E9TZ-12A650-AEB (replaced E9TZ-12A650-AEA) .. Processor & Calibrator Assy / Marked: E9TF-12A650-AE1A or E9TF-12A650-AE2A / Obsolete

Next time, try Rock Auto for a reman (as I suggested in the P/M), it'll be one hell of a lot cheaper than 300 bucks! Give them the part and ID engineering numbers.

 

Have you opened up your PCM to see if the capacitor is leaking or swollen?


All vehicles, whether new or old have more money invested in them than they are worth. This argument makes no sense, but I hear it all the time (probably to justify the owner's actions).
One has nothing to do with the other.
The real question is: can I do something financially smarter with the repair money? This answer may differ depending on your personal abilities and desires.


NotEnoughTrucks2014 is absolutely correct. The PCMs are going out because of a different problem. It just takes a while for that problem to surface.

 

Not sure how sensitive they are to this, or if the ECM is going to react before other items on the truck, but what about an overcharge situation where the alternator is putting out 16 or 17 volts instead of 14.5v?
Doesn't happen that often in my experience, so not sure what, if any effect that would have on the ECM's

Thanks

Paul

 

 

When you check codes, the very best outcome is a pass. This will be 11 or 111 depending on the generation of EECIV ECM that you have. I don't have a comprehensive list, but there are conditions that will result in a code that may not light the CEL. Best to read them. Don't assume! Also be sure you run KOEO, CM, and KOER tests.

It's also safe to say that if you get the system pass code, all is well with the ECM. It is prudent to check your fuel pressure. Also, ignition faults will not set codes. A faulty PIP in the distributor can cause intermittent no start conditions. A failing fuel pump may cause the engine to run poorly. None of these faults will set codes.

And yes, your IAT and ECT definitions are correct.

 

I had to look up ECT and IAT, so could you nudge me a little on KOEO, CM, and KOER? I'll go have to find my code reader first off. I really like the temperature sensor approach, because it is most definitely temperature related. I am curious if the ECM is fried or not.

 

This should help.

EEC IV Self Test hookup

KOEO = Key On Engine Off
KOER = Key On Engine Running
CM = Continuous Memory

Noticed your original post mentions this happening every couple of years. Can you confirm the interval?
Also, if you are guessing, IAT's and ECT's are a lot cheaper than ECM's

Ignition components like PIP sensors and ICM's also can be temperature sensitive. (Yes, there is an ignition control module mounted to the distributor on your '89)

 

It's been a while since I worked on those but in general, the codes just lead you to the general circuit and are in no way telling you what part to buy. More often than not it's a bad ground or bad connection. All of the harness connectors are somewhat self cleaning and should be unplugged , inspected and plugged back in. The real nitty gritty diagnostics require a break out box and the ability to comprehend the data from it. Also, when I first started working on those and Ford was tight with the diagnostic info, I had Motors and Mitchells flow charts. Both almost always ended up at "Replace ECM and retest" I never replaced a bad one in a Ford, ever.

 

Well said. My experience is similar, but I did have one confirmed bad ECM. Only one.

Some issues can drive you right up the wall as the fault may put the ECM into open loop, or limp home mode, but generally, if the engine runs, the ECM is OK. If you are getting garbage out, you likely are putting garbage in. Problems 99.9% of the time are sensors or damaged wires.

Still, age is catching up and those electrolytic capacitors do dry out after 30 odd years or so. Some odd problems have been reported and solved by replacing the few capacitors in the ECM and I'm sure that is all the rebuilders do anyways.