wb22rules

Usually alldata spells things out once you can find it, but I often on the first time on a certain repair when it isn't crystal clear to me seek second opinions from places where some members may have experience with it.
I appreciate the added insight I have gotten from the replies here, and I understand most of us who dont do this for a living probably havent had to troubleshoot failed computers often, I have been fixing my own vehicles for most of my life and have never had to deal with with a failed PCM before this one.
The values the solenoids were supposed to return were between 13-27 ohms, and 20 is square in the center of that range, so I have to be comfortable the 4 solenoids with that value are as they should be. I would guess the one that is way low out of spec probably needs to be replaced.
I will be investigating options for that and see what that turns up

wb22rules

Found this:

Transmission Application E4OD : Solenoid Resistance (Ohms)
Shift Solenoid 1 : 20-30
Shift Solenoid 2 : 20-30
Torque Converter Solenoid : 20-30
Coast Clutch Solenoid : 20-30
Electronic Pressure Control : 4.0-6.5

as well as a helpful link for troubleshooting http://oldfuelinjection.com/

It looks as if my trans solenoids are not shorted, which is good as they looked to be possibly procey and a bit of work to replace.

Since halfway through my following the disgnostic for the circuit failure codes the disgnostic told me to replace the PCM again I guess thats the second opinion I need to go ahead and buy one.

I do want to run through the other code charts though to see if i can find a cause, since everywhere I go in this quest states the computers rarely fail without reason.

wb22rules

Computer ID update.
When writing down small funny looking fonts, go get a better light when you can, I did not and it turns out my last two digits were not VA, but YA.
Now YA does not show in the big list I found but it makes a lot more sense than what I thought I had.

I did go grab the PCM I pulled earlier this week at the pick a part, but after inspecting it and my PCM under a good light (Bright midday sun) I was able to see that both have capacitors that have leaked, so I will be replacing those before I try to use either of them again as that could very well be issue. I just have to get some cleaner to remove the goop that covers them so I can desolder the leaked caps and solder in the new ones I will grab at Radio Shack (each PCM has two 16v 47microfarad caps and one 63v 10microfarad capacitor). I think I still have some that electronic protecting goop in the garage somewhere to reapply after I am done, I will have to dig around, I used to use it on fire alarm devices in parking decks.

wb22rules

Well I tried to repair the used PCM I grabbed from the junkyard, but the corrosion around where the capacitors had leaked was pretty bad so I just figured on it being soldering practice as it had been a year or two. Of course once installed the truck would not start.
So I proceded to remove the three capacitors from PCM that came out of my truck, only one had been leaking but I replaced them all. Where the one had leaked there was a little mess underneath, once I cleaned it up I could see that the corrosion had eaten through a small trace on the surface of the pc board, luckily there was a solder pad not far in each direction from where the break was. So before I replaced that capacitor I used a small single piece of some small stranded speaker wire to solder between those pads to reconnect that trace. Reinstalled into truck and Viola', she is running perfect and no check engine light or codes . Took a test drive to the store and back and all is well.
I have to guess that trace was part of the control or trigger circuit to turn on the transistor that supplied the voltage my truck had been lacking to all those sensors and outputs. From digging around this issue it appears it is not terribly uncommon for trucks from this vintage to have leaky capacitors occur on the PCM, due to the quality of the capacitors available during that time I think

Now I just need to find some of that coating spray again, the wire I used was not insuulated, and I can't have it vibrate or get bounced into the side of the capacitor as that might be fatal to the PCM. I will take some pictures when I take it back apart to show what happened. I need to spray the coating over the areas I worked on and the wire to make sure the repair lasts.

DPDISXR4Ti

Indeed it is quite common for the capacitors to fail in this manner. In fact, I would say more have failed than have not!

I bought a small batch of upgraded replacement capacitors a few weeks ago. I really should list them for sale as a "kit" for those that don't want to go through the trouble of figuring out the right ones to get in 1-off quantities.

wb22rules

^^You wouldn't know of a good source to get that aerosol coating I need to recoat the areas I worked on would you??

The stuff I used to use and can't find the last can of was called Humiseal, but I struck out hitting everywhere in town today that might have something similar.

I guess I am going to need to order some of it online so I can recoat the PCM.

wb22rules

I did a search for conformal coatings, as that is what I remember that Humiseal stuff called itself. I found Humiseal, but could not find anywhere that let me order less than a case of it at a time. I did find a product made by TechSpray called Turbo Coat that I could buy a single can of from a place called All Spec. It was $20 buck for the can, there was a 8 dollar fee for orders under $25 so I added a $5 dollar roll of Super 88 electrical tape to save 3 bucks.
Hopefully it will get here this week and I can get back to using the truck

RLXXI

I didn't see where it had been mentioned so I have to ask have you had the battery and alternator tested? I've seen batteries with bad cells and alternator outputs so off scale that it would make a vehicle run all kind of stupid throwing all kind of codes from the pcm.

And I don't mean load test the battery with one of those load testers with the coils that start glowing, I mean an electronic tester, it can verify a bad cell even though you can start it it still may be bad, and the alternator can put out recommended voltage but if the output is dirty it'll wreak havoc on the entire system.



.

wb22rules

Those were the first two things I wanted to check myself, although I did not do a thorough test on them I just did the backyard basics.
I did swap the battery with another known good one to make sure it was not a dead cell issue, truck was the same with both batteries so I eliminated a bad battery as the cause. I did not have the output of the alternator checked outside of the truck, but did verify it was working as well can be checked by seeing the voltage levels while running and verifying the truck ran with the battery disconnected. It could be putting out dirty voltage at this stage of its life, but it wasn't the cause of the problem I ended finding or fixing.

Oh I just got a txt that the aerosol has shipped, kudos to All Spec

DPDISXR4Ti

Looks like you figured this out. Good thing, as I didn't have a clue so thanks for researching. I know some people just spray the fresh solder repair with WD-40 (or similar) as a cheap alternative. No idea how effective that is long-term.