wb22rules

This is the picture of the PCM after I repaired it, and before I sprayed it with the acyrlic conformal coating, the circled area is where the corrosion was that damaged one of the traces on the surface on the board. You can just see a glint of the copper wire I used to fix the messed up trace at the right of the drawn circle.

wb22rules

I was not able to get a suitable picture with my camera closeup of the area and the repair (Operator error ) , but I found one on the web that I used to draw this illustration of what happened up close.

The red circle is the corrosion area from the leaky capacitor

The green circle is the area where the corrosion ate the trace on the circuit board of the PCM

The thick blue line represents the little copper wire

The small blue circles are the solder pads where I soldered the copper wire to flow around the messed up trace.

VettsnFords

Fixed PCM or EEC which was in its death spiral & trying to take sensors, actuators, etc with it by displaying bogus failure codes. Interesting that one of the codes displayed you believed was for low internal PCM voltage. That clue & some experience rebuilding pcbs for printers led me to three blue electrolytic caps on the board. Their values were 47, 47, 10 uf. Only one tested close to that. Replaced all three, total parts cost less than $3. Computer rebooted, engine started. Looks like they are filter caps between the +12 bus & ground & + 5 bus & ground.

Hope this helps anyone who has a PCM from a 92 truck with a 5.8L beast shaking & baking everything within 10 ft of it. This type of cap notorious to short & bring down power supplies.

Don't attemp going down on your pcb unless you have the tools & good eyes. Had to repair a trace I broke when removing a cap. Next one I do, I'll crush the cap & leave the leads in the pcb to solder the new one to.

wb22rules

Thats a great idea leaving the legs in, avoids having to remove the conformal coating and reapplying it as well as is much easier than trying to use a solder sucker to clean out the holes and stuff. With 50 year old eyes and hands it was much harder than I remembered when I was in my 30s and did that stuff sometimes at work.

JohnPaul

Exact same think happened to my 95 4.9 e4od. Running great then out of the blue running and shifting like crap, cel and a long list of trouble codes. With lots of egr and trans codes.

With the help of this fine forum and after a lot of time under the hood I found the same 2 fried caps in the eec. One of my trouble codes was 512 and Sean called it correctly from the start.

It was suggested by many her to double check and clean all grounds. Even add a few. Turns out a ground problem most likely caused my eec failure. I found the taillights were not working, I traced it to a ground problem them soldered in a new ground.

I got an eec from Flagship One Parts in NY. Paid $127. So far so good. Good luck with your repair. Still have my old eec. Will try to repair it as you did.

wb22rules

Just an update that the computer repair is still going strong.

I am dealing with a different issue at the moment but I think another thread has me pointed in the right direction about a coil that wigs out when the weather is humid or wet.

Chris_1

iTrader: (1)

Very interesting thread. Thanks for posting all that.

ericantonio

This is the most interesting thing I'll read this whole week!

But the question on my mind: Is the truck really a CA truck? Or were the errors (bad electrical components) giving you codes that the truck is from another state?

wb22rules

The error codes pointed to failures everywhere, the ID on the PCM I initially made was wrong as I confused a V and a Y due to funky font.

The PCM ID I had wrong pointed to a CA vehicle with a manual trans, once I figured out my mistake the PCM code I had made sense for a VA vehicle with my auto transmission.

Thanks for the interesting comments, I tried to document what happened so others with the same issue could get on track quicker. Lord knows I have benefited from others doing the same many times

wb22rules

Update:
No problems for 3.5 years. Was working on the cooling system, went to start truck, immediately saw the cap was off the radiator (hood was up) and turned the key back off after 1/2 sec of cranking. Put cap back on and went to start the truck and it was like before the pcm repair, barely run, checked codes, had the whole list again. Figured my pcm repair bridge wire must have broken, removed pcm, inspected it, looked fine, barely pushed on bridge wire I added to insure it was attached at both ends and it was. Reinstalled, truck started fine and has been fine for a year and a half since. The repair must have missed me lol. I won't quick abort a start like that again though just to be safe.
Just got antique plates on it this year, no more registration fees or inspection requirements