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Backwards problem - it starts but I can't shut it off with the key!

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philbobaggins52

Backwards problem - it starts but I can't shut it off with the key!

Hi all! Phil here, Adelaide in Australia. Over the last 4 years I have been restoring a 1986 F100 302 4WD C6 which spent it's first 20 years as an ambulance in country NSW. Over the last few months I have been rewiring it, virtually from scratch. I have installed a Kwikwire 22 circuit wiring harness. Because the engine uses EFI, I decided to open up and copy the relevant parts of the EEC IV harness and connect them to a new 60 pin connector and sensors etc, and overlay this harness onto the Kwikwire job. Long story short, the engine starts readily (both EEC and fuel cut-off relays obviously work fine, along with an unknown list of sensors). The problem is, when I turn the ignition switch to off, the engine keeps happily running. I suspect the ignition switch wiring but my limited understanding of the start-run-stop process means I don't know where to look to resolve this issue. FWIW, I put a toggle switch in line of the pin 30 power feed relay to the high pressure fuel pump, which does cause the engine to stop when switched. My main difficulty is that I have been unable to find any references to the start-stop sequences when you have the ecu controlling ignition and fuel delivery etc. I mean, if I knew the sequence, that should give me clues where to look for whatever is latching the fuel delivery and ignition circuitry to "on"". So, can anyone please point me towards a resource that describes this sequence? Any thoughts would be very much appreciated! :)

Gary Lewis

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

Welcome! Glad you joined.

You may want to post the same thing in the main section as it'll get more attention than here. But we can work on it here if you want.

By the way, we have a map (Bullnose Forum/Member's Map in the menu) and can add you if you'd like.

As for your problem, I think you have a mis-wire in the ignition switch circuit such that the W/LB wire going to the coil is hot even with the key off. The way the ignition circuit works is that the EEC causes TFI module to ground the DG/Y wire on the coil and then take the ground off when it wants to fire a plug.

But you must also have power to the EEC when the key is off or it wouldn't be telling the TFI module to fire the ignition. So something is pulling in the EEC Power Relay. And that W/LB wire is what pulls the relay in, so if you have power to the coil you also have power to the EEC.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

ArdWrknTrk

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

In reply to this post by philbobaggins52

Welcome Phil!

You're going to find ignition diagrams and testing information in the EVTM pages. https://www.garysgaragemahal.com/start--ignition.html

This would be Documentation/Electrical/EVTM's/appropriate year.
Not all years are shown because much of it is redundant and it's a lot of work for Gary.
A 5.0l Windsor for 1986 with EEC-IV ignition, start and run is linked, but there is much more to the manual if you follow the steps above.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

grumpin

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by philbobaggins52

Welcome!

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6-Sold
1992 Bronco XLT 4x4 351W E4OD
1998 GMC Sierra SLE K1500 350 4L60E
Arizona

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by Gary Lewis

Hi Gary! Thank you so much for such a speedy and helpful reply! It feels as though a load has already been lifted :).

I will study your words and diagrams asap and hopefully find the mistake(s) in my wiring - I expect the answer will be obvious as soon as I know it! I will give you feedback on progress as it happens.

FWIW, I had the engine running for a good five minutes this morning and it sounds mechanically sweet and with a steady exhaust note (I have to time it accurately next). All very promising!

Again, many thanks :)

Kind Regards, Phil

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by ArdWrknTrk

Thank you Jim for taking the time to help - very much appreciated! :)

Kind Regards, Phil

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by grumpin

Thanks Dane! I can tell there is kind help aplenty in this Forum! Good to be here :)

Kind Regards, Phil

Gary Lewis

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

In reply to this post by philbobaggins52

Welcome. I think you'll find it is a simple problem, but it might be tricky to find. However, we are here to help regardless of how deep the problem is.

Gary, AKA "Gary fellow": Profile

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by philbobaggins52

Hi again Gary! After a week where life got in the way and a mild bout of food poisoning, I have some preliminary feedback on the issue :). My son and I followed your clues re coil voltages, without finding a cause of the symptom. We were suspicious that maybe somehow the alternator was holding up whichever circuits had latched on while the engine was running (because even disconnecting the battery wouldn't stop it). We found that disconnecting the exciter wire enabled the engine to shut down instantly by turning the key to off! A little bit of internet searching on alternator circuitry suggested that it was indeed possible to have this non-stopping sequence if something is missing from the circuit (likely in my case because I am adapting a Kwikwire harness to EFI control). So, I put a 6 amp diode between the exciter wire and the alternator. Like magic, the engine now turns on and off correctly! What I also discovered on the original Ford harness were two light bulbs in the exciter circuit which I had omitted from the rewire. Does it seem likely that these bulbs (they look like dash display plug-ins) are essential for correct running of the alternator? I have not yet completed wiring in the instrument cluster, so there are no connections to the cluster as yet (and no gauges like oil pressure/charge etc). I do wonder will the alternator function properly as wired - can you please make some observations about all this?
Again, many thanks for your support! ::))

PS - please feel free to add my location to your map :)

ArdWrknTrk

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

Hi Phil,
I'm not Gary but in the US if your truck came with a charge indicator lamp you need to retain it because it provides 'exciter' current to the field winding of the alternator. This is a light green wire a red stripe (iirc it's circuit 904???)

The lamp would be jumpered on the cluster flex circuit with a 512ohm resistor so if the filament breaks the alternator will still charge.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

Hi Jim, thanks for your input!

I reckon I'll transplant the globes and wires from the old harness to the new, plus get onto finishing wiring to the cluster. If this solves the no-stop problem, we can move on! I'll see if the old harness has a resistor too ::)).

I'll let everyone know how this goes :)

Gary Lewis

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

In reply to this post by ArdWrknTrk

Phil - First, you are now on the map.

Second, I'm confused. You said your truck is an '86, and here in the States an '86 was the first year where the idiot light configuration wasn't offered. IOW, an '86 US truck wouldn't have a charge light like your harness does. And, it would have only had one in the alternator circuit, which is indeed #904. So where was your truck made? And do you have an ammeter or idiot light in the cluster?

As for the diode fixing things, that tells me that your alternator is feeding power back on the excite wire. But it shouldn't. None of the trucks w/o the charge light had a diode and the excite wire goes right back to the ignition switch where it would power the ignition if it was feeding power back.

So there's something different about your alternator. But if it works and if a diode fixes the problem, that's good. It shouldn't cause a problem with another alternator. However, a little indicator bulb probably won't pull enough current to run the ignition, so that might fix it as well. Or both the diode and bulb for a belt & braces approach.

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

1986 is also the last year a Ford pickup didn't come with a charge indicator lamp in the cluster as standard.....

I definitely should have asked how an Aussie truck might differ from the "same" model sold here in the U.S.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

LOL! Yes, the '86 trucks were an oddball that way. Hadn't thought about that.

For those that didn't "twig" to what we are talking about, through 1985 in North America there were two ways the dash came - full gauges or gauges with indicator lights for oil pressure and charging. The full gauge package had an ammeter that was "less than informative". In 1986 the indicator light option was dropped, but starting in 1987 there was no option for a full gauge package and all the trucks got an indicator light for charge.

IOW, at some point in the 80's Ford realized that the ammeter was a poor offering. It required a shunt, a piece of wire with more resistance than the rest of the wiring, to generate the small voltage that drove the ammeter. But that wire was limited in current capacity and as the output of the alternators was set to go through the roof, if you put a wire in that would handle the higher output you'd never ever see a discharge when the alternator failed.

So 1987 they went back to the age-old indicator light, which was the best solution all along.

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

1987 on clusters all have a voltmeter as well.

These seem much more responsive and accurate than the old ammeters ever were.

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

Yep, Ford finally got it right.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: Backwards problem - it starts but I can't shut it off with the key!

Administrator

In reply to this post by Gary Lewis

If he has put a GM style alternator (most of the one wire ones are) they are famous for back feeding through the idiot light wire.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by Gary Lewis

Hi again Gary. Here's what I know about this F100: On the air cleaner box it says date of manufacture was July 1986. It seems the truck (or cab/chassis) was at least partially assemble in Australia (I vaguely recall someone once said these motors were made in Canada - no idea if true). One of the regular stumbling blocks has been that I have yet to find a set of wiring diagrams which truly reflect the colour scheme in my harnesses. The nearest I have got to this is a set which is meant to cover 1984-1986 F-Series/Bronco by Haynes. I suspect that Ford Australia supplied the harnesses, using their own colour schemes and switch components (Bosch Australia is stamped on most electrical components from memory). What I have been doing so far is using a mixture of clues from the Haynes manual, from tracing wires on the original harnesses, from diagrams such as the ones you originally posted to help me, and now I have Kwikwire's scheme plus the new EFI harness I made using colours as close as I could source here. I do plan to draw up a set of wiring diagrams to describe what I have done, for the times when understanding what is what becomes necessary. Wish me luck!
I'll take a photo of the dash cluster and post it to you - there's a +/- gauge to show charging/discharging and a charge light.
The alternator is a two wire one with internal regulation - so, the B+ connector and the exciter connector.
Right now, I think we'll be connecting the bulbs and the cluster into the harness, in part to make sure the oil pressure is ok and to monitor temperature, but also to hopefully solve this won't stop issue.
I will post again once we've done this :)

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by ArdWrknTrk

Hi Jim! I reckon I've answered your queries in my (lengthy) reply today to Gary's posts ::))

philbobaggins52

Re: Backwards problem - it starts but I can't shut it off with the key!

In reply to this post by 85lebaront2

Thanks Bill!! I'm not sure about the manufacturer of the alternator, but it seems to be well described by your comment on GM examples! ::))