PCM Wiring Harness for '95 Ford 5.8L federal emissions

E350 · 01-23-2017, 02:57 PM

Hey guys and gals, I have a question for you (and for mgmetalworks if he is available). I am learning that 80% of vehicle electrical problems are with the wiring itself and only 20% with a component, especially on older vehicles.

The following question is somewhat Sportsmobile-related because the engine at issue is a common engine (5.8L or 351) in older Ford E150-E350 Sportsmobiles.

Symptom is that my 1995 Bronco with the 5.8L starts with the SPOUT jumper out but not with the SPOUT in. I replaced the capacitors (badly) in my EEC-IV PCM and it didn't help. Thinking that my poor soldering skills were to blame, I just installed a reman PCM and it didn't help. And in my heart I know it is a wiring problem (I am reading a great book on diagnosing vehicle electrical problems and I will post a thread introducing that book).

So can anybody source a PCM wiring harness for me: F5TB 12A581 P260F

And if not, can mgmetalworks or you other electrical gurus suggest how (after I take out my wiring harness) I can rewire it using the same connectors? Is that even possible?

Thanks in advance...

mgmetalworks · 01-23-2017, 03:15 PM

Take the harness that you have, carefully unwrap it and comb through it to find the potential problem?? I wouldn't go through the time and expense to make a harness. If you can't source a new one, just clean up/repair your old one.

One tip... don't unwrap the whole thing at once. They quickly become rat's nests. keep it bundled every few inches with tape and just work through one leg at a time.

E350 · 01-23-2017, 03:37 PM

Thanks MG, is there a tape you prefer for re-taping?

And one more thing, when I took the PCM out of the firewall yesterday, I noticed that it was wet and the case was corroding, the firewall alcove where the PCM is installed had water on the bottom. And I have never liked how and where Ford placed the PCM. Can I solder and extend the (I haven't counted them yet, but ~64?) wires 6 inches or so and place the PCM in a water proof box (like a Pelican box) on a bracket I fabricate above the fender in the engine compartment? I assume since it is DC volts I cannot extend them 3-4 feet and place the PCM under the driver's seat or 2 feet and on the transmission tunnel in the cab, right?

(Your Cummins conversion is looking great!)

E350 · 01-25-2017, 09:06 AM

Update: Believe it or not, my Ford parts contact pulled a 22-year old rabbit out the hat. And found a new old stock wiring harness with the exact part number!

But it is $295. I bought it because it is a once in a lifetime opportunity and to honor the efforts of my Ford parts contact who has become a friend over 15 years.

So I bought it. But now I am throwing money not at components, but at wiring.

Irony alert...