Has any one ever change the transistors out in the pmd and had good success it working. I removed the transistors from my old pmd found one of the transistor bad.

I have used a #5, #9, and using a #7 now. No change that I can tell, I'm sure it does a little bit, such as adding more fuel just not enough to tell big difference IMO. I know some here run or ran thier truck with out one and didn't see any change.

How did the transistor come out?
Just pulled it, no un-soldering?

I think he is referring to the two transistors bolted into the back of the PMD (covered by the plastic cups). IIRC, some people have stated that just tightening the fasteners on these transistors will eliminate some intermittent problems... seems to make sense that replacing them may fix a faulty PMD.

If you have the tool to replace it, I don't see why not.

As far as I know, I have not read that somebody here has done it but there will always be the first one. You can be that one.

If you are successfully, you can tell us how?

Oh sorry I guess I didn't understand the question. I thought you meant the resistor and just called it a transistor... Sorry about that. Please disregard my first post.

Did you buy a new transistor or pull one from a PMD?

Could be a good cheap fix for the PMD if the transistors are the prob and relativley easily diagnosed/replaced.

I order new transistors that will be in 2 to 3 weeks. The ones that I took off were very corroded and very dirty on the connections. Guess I will see
if it works or not.

keep us posted...I'd love to hear how it goes

It would good news if it works. How much $$ are the new transisters?
I have 2 extra PMD's that could use new parts if it works.

Good luck with the repair - shame, nobody did a search on FSD\PMD B4 money was committed............

If you come up with a successful transistor repair be sure to document it fully with photographs, it has been attempted before unsuccessfully by many, normal removal from the board is destructive process, if you have transistors that "were just unplugged" something is wrong with the build of the driver. As GMCTD suggests search the forum for PMD or FSD several photos where the sockets/pins of a properly intsalled transistor are soldered and entire assy is conformal coated, removeable by conformal coat "chemical-peeler", or mechanical methods which usually destroy the driver

The transistors unplug from pmd and one check good and one check bad. I did not see any sorter on transistor attach points. But I just try to removed transistors from one pmd. This pmd was attach under the front bumper and was under water and quit later. Later removed pmd to left fender with a heat sink and computor fan with out side air blowing on the heat sink. Have had no trouble with pmd relocated.

The Emitter and Base conductors are soldered into circuit pads on the pcb on the opposite side of the heatsink, then the housing is filled with thermally-stable epoxy, which also seals the conductors into the thru-passages in the 'sink.

The cover on the opposite side may be pried off with a screwdriver, exposing the epoxy-filled pcb area in the module case - sometimes the solder-pads may be seen where the epoxy potting is thin.

I found a long-time weather-exposed 34583 module on a 'Burb firewall in a boneyard, all rusty and oxidized and nasty - aware of the inherent beauty in this bedraggled module, I prompty rescued it, placed it in a plastic bag, and triaged it to my garage.

A hot-water scrubbing with 'zone engine cleaner, then hot soapy water, pulled the resistor-pak, then dipped in CLR x 2, then hot soapy water x 2, then hot water rinse, performed the chromium-oxide burnishing procedure, and in with the appropriately-calibrated resistor - it has been dutifully interfacing PCM to IP on my truck since that juncture, back in ought five.

There will be a pop-quiz, later....................

Looks like you may have found why yours & some others have died poor or no solder joint, because inquiring minds needed to know and because I had a bad one hanging out I tried to unplug transistors from it, I tried the gentle route & when that wasn't happening I got out the needle nose vise grips, again gentle at first then "with effort" they finally came out but not intact see pics.

When the transistors come out the PMD looses it's seal and all the magic smoke comes out. Some people call it the "Black Box" others "Black Magic" but when all the smokes gone it's called burnt toast.:rolleyes:

Could I have a quick run through on the PMD repair procedure?

Remove nuts, clean with air or light rubbing the connections, then tighten to 1/4 turn past finger tight? Then, toss the little plastic covers?

Then, find some heat transfer goop at a PC repair shop and remount it to your remote mount?

Starting the PMD downward spiral on a used on mounted under the bumper.

Thanks mucho!

Loosen the nuts, run down finger tite, tighten 1/4-turn will scuff the oxides, restore connection.

Toss the covers.

After reinstall, try it for a while - if ok clean with lacquer thinner, RTV the crack around the module for weather-proofing, install it outside the engine bay