Return of Code 31...

[85lebaront2]

I'd even be fine with bad results, if results were consistent... but this is crazy!

I think the first wire to replace will be the EVP Signal wire that goes straight to Pin 27 on the ECU via Wire 352. There are no splices with other wires for that portion of the system.

I'm pretty sure VRef is good as the 5 volts seems consistent. It comes from connector 260

The Sig Rtn is like a shared ground between two other sensors, and I'm not getting errors from any of those. That's at Splice 255.

I need to check these visually, I've just been looking at the EVTM. But, Wire 352 seems like a good candidate besides switching out the connector and the pintle experiment...

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 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.

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]

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!)

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]

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.

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 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.

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]

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.

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]

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.

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]

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

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]

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.

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]

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?

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.