EEC- IV / PCM repair
08-27-2014, 10:15 AM
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EEC- IV / PCM repair
Just wanted to share with everyone an issue that arose for me yesterday.
I have a 94 4x4 with the 5.8L. It has been running fine since I bought it a few weeks ago. The other day, I started it up and all was good to go. Yesterday morning, I attempted to start it and all it would do was spin the engine and constantly cycle the fuel pumps. The other thing is that I could not read any codes coming out. I have the little code reader for $30 as I like to see numbers and not count flashes.
After reading this forum and running a few tests, I concluded that the Powertrain Control Module, aka PCM, aka EEC-IV stopped working. So I pulled it out and opened it up. Here is the technical aspect of this particular post:
The PCM is a sealed double sided circuit board. On one side, you will see nothing but very small surface mount components. On the other side you will sell all though hole components. These include a hand full of transistors, IC chips, resistors and capacitors and such.
I have been a Amateur Radio (Ham) geek since 1993 and know my way around electronic fairly well. The first thing I notice is that two of the three electrolytic capacitors have corroded to the point of 100% failure. This is a very common problem with these. They normally operate for about 10 to 15 years in a stable environment. Given the conditions found inside a vehicle, my 20 year old ones were lucky to have made it this far.
I called around and only found one place to order a replacement and they wanted $200 plus a core charge plus a weeks wait at a minimum. No. Freaking. Way.
I made notes of the capacitor values, their polarization direction on the boards and took pictures as well. I then carefully unsoldered them off the board using solder wick to make sure I removed all the old solder. I then drove my other car down to Radio Shack (yep, still in business) and picked up two 47 mF caps and one 10 mF cap. They needed to be rated at least 16 volts. The higher the rating is no issue, but DO NOT go lower.
Total cost, 35 bucks. For capacitors????? No, I bought a new soldering iron as well since mine was old and crusty and I have been wanting a new one any way! The cost of the three caps was $4.50.
After arriving home, the new capacitors were carefully installed and connections checked. I reinstalled the PCM into the truck (pain in the butt due to close proximity of the fender skirt). After checking all connections, I gave a quick prayer (no, really) and turned the key. Started right up and ran like a champ. Perhaps a little better since the components were functioning as they should. Oh, I did say that only two of the three caps were bad, but I replaced all three. I figured since I was in there, might as well hedge my bets and take care of a future problem.
So at the end of all this, here is the take away. Normally, when an electronic goes bad, it is not the whole thing. There is also almost always a very visual indication that it the component is bad. Bulging, burnt, broken, etc. Aside from the transistors and IC's, all of these parts can be replaced. Even the tiny surface mounts can. It's hard, but they can be fixed. The IC's, if they have failed, would need to be tracked down. Depending on other applications aside from Ford, it could be difficult to know what they were used for. The main chip, which holds the memory would be the hardest. That and the fact that a new one would not have the code in it.
All in all, total time was about 1.5 hours going slow. I had to pull the PCM, unsolder the old components, solder the new ones in and reinstall the PCM. Saved a
-ton of money though!
Sorry, I did not think to take pictures, but if anyone has a PCM picture with the cover off, I can indicate what I did.
I have a 94 4x4 with the 5.8L. It has been running fine since I bought it a few weeks ago. The other day, I started it up and all was good to go. Yesterday morning, I attempted to start it and all it would do was spin the engine and constantly cycle the fuel pumps. The other thing is that I could not read any codes coming out. I have the little code reader for $30 as I like to see numbers and not count flashes.
After reading this forum and running a few tests, I concluded that the Powertrain Control Module, aka PCM, aka EEC-IV stopped working. So I pulled it out and opened it up. Here is the technical aspect of this particular post:
The PCM is a sealed double sided circuit board. On one side, you will see nothing but very small surface mount components. On the other side you will sell all though hole components. These include a hand full of transistors, IC chips, resistors and capacitors and such.
I have been a Amateur Radio (Ham) geek since 1993 and know my way around electronic fairly well. The first thing I notice is that two of the three electrolytic capacitors have corroded to the point of 100% failure. This is a very common problem with these. They normally operate for about 10 to 15 years in a stable environment. Given the conditions found inside a vehicle, my 20 year old ones were lucky to have made it this far.
I called around and only found one place to order a replacement and they wanted $200 plus a core charge plus a weeks wait at a minimum. No. Freaking. Way.
I made notes of the capacitor values, their polarization direction on the boards and took pictures as well. I then carefully unsoldered them off the board using solder wick to make sure I removed all the old solder. I then drove my other car down to Radio Shack (yep, still in business) and picked up two 47 mF caps and one 10 mF cap. They needed to be rated at least 16 volts. The higher the rating is no issue, but DO NOT go lower.
Total cost, 35 bucks. For capacitors????? No, I bought a new soldering iron as well since mine was old and crusty and I have been wanting a new one any way! The cost of the three caps was $4.50.
After arriving home, the new capacitors were carefully installed and connections checked. I reinstalled the PCM into the truck (pain in the butt due to close proximity of the fender skirt). After checking all connections, I gave a quick prayer (no, really) and turned the key. Started right up and ran like a champ. Perhaps a little better since the components were functioning as they should. Oh, I did say that only two of the three caps were bad, but I replaced all three. I figured since I was in there, might as well hedge my bets and take care of a future problem.
So at the end of all this, here is the take away. Normally, when an electronic goes bad, it is not the whole thing. There is also almost always a very visual indication that it the component is bad. Bulging, burnt, broken, etc. Aside from the transistors and IC's, all of these parts can be replaced. Even the tiny surface mounts can. It's hard, but they can be fixed. The IC's, if they have failed, would need to be tracked down. Depending on other applications aside from Ford, it could be difficult to know what they were used for. The main chip, which holds the memory would be the hardest. That and the fact that a new one would not have the code in it.
All in all, total time was about 1.5 hours going slow. I had to pull the PCM, unsolder the old components, solder the new ones in and reinstall the PCM. Saved a
-ton of money though! Sorry, I did not think to take pictures, but if anyone has a PCM picture with the cover off, I can indicate what I did.
