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I've had this truck for several years. 1996 F350 7.5 5-spd. This truck has slowly developed a very slight hesitation, and it has very gradually gotten worse. I have the factory wiring book. I eliminated the inertia switch by bypassing it while I was driving. No improvement. It happens with both tanks. Just wondering if anyone else has experience with this trouble code.
So the question becomes have you ever cleared the Stored Codes by removing a battery cable?
Have you recently removed a battery cable for some reason? Doing so frequently triggers a Code 512 that is stored in memory, aka Stored Codes. It takes 40 or 80 drive cycles for the computer to clear a Stored Code on it's own. You can manually clear the Stored Codes by initiating the KOEO tests and Stored Code display, then removing the STI jumper as the first set of codes are displayed.
There are several reasons a code 512 will set
It's an ignition diagnostic monitor code
A blown fuse KAM will cause the code to repeatedly set
A failing ignition module or processor will cause the code to set
I'd pull the processor out and check the caps, then do a few of the pinpoint tests in the PCED to check the processor power and ground wires
I did have the battery disconnected while I did some other work on it. The hesitation was already happening before that, and I got that trouble code then also. I did pull the PCM, and I checked the pins on the connector. All of the hots (KAM good) and grounds were there. I looked in the PCM case, and the board was clean and visually clean on both sides. I had a not-start problem about 4 months ago. I ended up replacing the ICM (with Motorcraft ICM), and the coil. The small shuddering while driving continued. Fuel pressure is a 40@idle rear, and 30@indle front. Hesitation happens on both tanks. I'm going to put the PCM back in and look around some more. Thanks for the replies.
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I decided to have another look at that PCM. I looked at the capacitors. There are two that have some corrosion near the soldered joints. I'll let you guys look at them and see what you think. One of them feels like it's hanging on with one leg. I'm going to order these three capacitors right now.
I might have those pressures wrong. I did that test several months ago.
For anyone looking for these caps, here is where I found them. I hit the buy it now yesterday. The seller listed the ratings on these - some sellers of these do not (duh). When they get in and I get the PCM in I'll report back.
I also will mention. When you deal with the ignition system, especially the ICM. Make sure you use heat sink compound on the back of it and not dielectric grease as the module won't be able to cool down properly. Most ICMs are garbage so good on you for getting a motorcraft one. Nice catch on the caps.
I live near a small town where I could not find thermal paste at any parts store, but I went to a cell phone repair place and bought a single application thermal paste syringe, and used it on the PCM.
Got the new capacitors in. Test drove the truck, and the engine seems to run smoother, but not quite all the way. I'm going to be looking into it more.
Last edited by Dr. Driveway; Sep 30, 2025 at 11:31 AM.
