Return of Code 31...

[85lebaront2]

I don't know on the carbureted ones, but, the early (1985-86) EFI systems the ground for the entire system was a plug attached to the battery negative cable clamp bolt. It would oxidize as it wasn't sealed resulting in all kinds of weird results.

[ckuske]

I haven't checked the plug itself, that's a good point.  I never thought of that, to be honest.

I did replace the terminal that attaches to the negative battery cable via that bolt (which is downstream from that plug!)

[ckuske]

So I checked the ground at the battery, it looked good.  I did sand/clean the connection though.

No dice, the KOER is still coming out really screwy across the Cardone and Ford (eBay) ECUs.  I haven't touched the BSE one again.  The KOEO was clean until I did the KOER.  When I do the KOER, the next KOEO while the engine is warm comes back with Code 31.

I'm going to let it cool down and try the KOEO later tonight.

[Gary Lewis]

It may not be just the ground at the battery.  The Bullnose trucks had a really poor grounding system, and Ford stepped up the grounding for the Bricknose trucks, and did even more on later year trucks.

I think that's because they found that the grounds weren't adequate for the EFI systems with computers.  For instance, the only true ground for the cab is the dinky wire from the engine to the firewall.  There's no ground wire from the passenger's fender to the cab, so just because there is a ground from the battery to that fender doesn't mean that ground is passed on to the cab.

So if the wire from the engine to the cab isn't there or if it doesn't have a good connection, or if the ground from the ECU to the cab is bad then there will be problems.  And probably flakey, unpredictable problems.

Given that, I'd make sure the grounds are good.  And it wouldn't hurt to add grounds.  I have HD grounds from the batteries to the engine and then to the frame, from the batteries to the radiator support, from the radiator support to the fenders, from the fenders to the cab, and from the frame to the cab.

[ckuske]

It's funny Gary, I was following the same path and I stumbled upon a bad ground!  It hasn't made a difference yet, though. (more later in this message)



I wouldn't even say the ground was attached - more like intermittently hitting the firewall from time to time.  I sanded the firewall and the terminal, and snugly attached it.  But, the KOEO is still failing at Code 31 again, and I didn't bother with the KOER.

So, I've now redone the ECU ground to the negative battery terminal, and the ground to the cab (G711).  I'm having a hard time finding G208 and G462 though, but there is so much junk it just may have to take stuff off to get a good look.

The other ground (hood to firewall) is good as well.  I'll try to verify the ground in the cab to the ECU.

[Gary Lewis]

G208 is next to the EGR valve, as shown in the first pic, and G462 is next to the carb bowl vent solenoid, as shown in the 2nd pic.

[ckuske]

Thanks Gary, I agree.  And thanks for posting so late there!

I just physically can't spot either of them... like they're not there?  (or I am blind, which is more likely)

I'll look again in the morning and send a couple pictures.  I also verified that G701 in the cab is attached to the dash support, so I should be good there as well.

Chris

[85lebaront2]

Ok, if you need it, here is what I have:



Large tie wrap through one of the padlock holes to keep it from being opened.

I bought it when my son was having issues with his 1986 F150 5.0L EFI system.

[ckuske]

Thanks Bill!  I may need it still, but I finally crawled in the very back of the engine bay and got things cleared up to look at the bundle that is right behind the EGR against the firewall:



You can see at least a couple wires with missing insulation. A wire (a white one?) that was attached to the engine ground broke off the terminal as soon as I moved the loom at all.  I think the best thing to do is pull the harness and fix all the issues.

How should I go about removing the harness?  Any tips?  Pull the connector from the cab through the firewall?  Or the other way around?  I haven't gone through the whole thing yet but it seems like I should be able to just disconnect everything and remove it, right?

[Gary Lewis]

Yikes!  That would explain a lot!

I put the grommet over the wire and then put the pins in the ECU's connector.  Then I put the connector through the firewall and inserted the grommet.  So I think I'd pop the grommet out and bring the connector out through the firewall.

[85lebaront2]

Lord knows what Ford used for wiring in the 80s, Lucas maybe? I have seen more absolutely cruddy wiring on these, most with crumbling insulation.

There really isn't any reason for a vehicle that age to have crumbling insulation. I dare say if you know anyone with the last of the real Packards you will see how long good insulation will last.

GM snapped up Packard's wire and cable division after they were taken over by Studebaker.

[ckuske]

It is less than optimal for sure.  My plan for now is to just cut out the parts that are damaged and put new wire in its place.

I have just started looking but there don't seem to be any good aftermarket options.  I don't want to rewire the whole truck, just the EEC wiring bundle.

Maybe I'll see if I can find one in better condition on eBay and go from there?  I really don't want to deal with this again.  Suggestions welcome!

I am almost tempted to build my own, but I don't want to buy 40 different spools of wire etc...

[Gary Lewis]

My ECU connector was cut from the harness.  That wasn't a problem as the harness would have placed the ECU in the left kick panel and I wanted it in the stock Bullnose position right of the throttle pedal, so I had to add wire anyway.  I just used black wire and extended the harness to the connector, soldered the connections and covered them with heat shrink tubing - lined with adhesive.

My reasoning was that if you follow whatever black wire you are wondering about either way you'll find the proper wire color at the splice.  So it doesn't bother me.

Given that, I'd pull the harness out and see if it can be salvaged.  Secure the ends of the harness on the bench so you know how long they have to be, and then start surgery.

[85lebaront2]

I probably have plenty of wires with the proper colors and even the correct EEC-IV connectors, problem is they are from 1987-1995 trucks so don't have the grommet nor the dash or dot or hash the 1986 and older used, but do have a weatherproof connector.

[ckuske]

I appreciate the offer!  I will get the harness removed from the truck and evaluate how to move forward.

After gently looking at the damaged wires, the truck won't stay running unless given a quarter pedal.  I think I just forced my hand my touching the bundle and it literally falling apart in my hands...

[grumpin]

Good find! What a mess!

[Gary Lewis]

1985 was the transition year on wire colors.  1984 should have hash and dots as well as stripes.  1986 has all stripes.  But in spite of the 1985 EVTM showing hash marks and dots on several wires I've found plenty of 1985s with stripes instead.

[ckuske]

Not much done today.  I labeled all the wires by circuit near their connectors, and got the 60 pin plug through the firewall.  I also unplugged most of the stuff... hoping to remove the harness tomorrow.

Although I am going to plan on salvaging, I am kind of thinking I should just got for it and build a new harness...  

I have found the female pins, and a good place to buy the wire (no hashes or dots, but  they have all the colors, and with stripes).  I'd be into the wire for about $300 total, less if I reused colors in various spots etc.  I'm not sure on using TXL or GXL insulation.

Anyway, my thinking isn't about how to fix it for "today" but more about what happens to the unpatched sections in a few more years... maybe I just build it from scratch and not have to worry about it.

More progress tomorrow (hopefully)

[Gary Lewis]

I understand your thinking.  But I'd wait until I got the harness out to decide.  It may not be as bad as you think, but it may be worse.

[ckuske]

I'm sure you're the voice of reason in this situation.  

Hopefully I'll get it out completely today in between work calls.  

My plan (if it really is that bad) would be to repair the existing harness and use it as a reference when building the new one.