complete wiring harness replacement

[Danny Campbell]

I have a 1984 F350 4wd 6.9L diesel with the T19.  I am in the process of restoring this truck and I am looking for a new updated complete wiring harness (bumper to bumper harness). I have found several new replacements from American Auto Wire and Ron Francis Wiring, however the harnesses are wired for gas engines only (An IDI option isn't available so far in my search). Can these gas harnesses be modified for the IDI or is there another option available?  I'm looking for new wiring as I'm updating much of the electronics to support the newer tech, so I'm not sure a salvage yard harness will work for me.

I would like to know what others have done and what my options are?

[Gary Lewis]

Danny - I hate to point this out, but the email I sent you asked you to start a thread in the New Members Start Here folder to introduce yourself.  There are several reasons for that, but the main one is so you have a chance to see the guidelines as that is where we keep them.

It is important that you have a chance to see and read them as we hold everyone to them.  So before we start discussing your harness questions, please follow that link, read the guidelines, and then start a new thread/topic to introduce yourself.  Then we can help you with the harness.

[Gary Lewis]

Danny - Thanks for the intro.  Well done, by the way.

On your harnii, there are several harnesses in a truck, not just one.  But I don't think you will find a new one.  And certainly one one harness bumper to bumper as there wasn't one.

Go look at the page at Documentation/Electrical/Wiring Harnesses.  That lists the individual harnesses that were available, and those in bold print are then listed below, showing the options from the Master Parts Catalog.

Perhaps someone else knows what the differences are between the diesel and gas trucks, but I think that was limited to the harnii under the hood.  Everything else was the same - I think.

So, what we might be able to do is to find the appropriate part numbers for the harness(es) you need and you might find one of them as New Old Stock.

[85lebaront2]

Having never worked on wiring on the older Diesels I can't say how much difference there is. I have determined that a lot of the gas engine variations were done with harnesses that plug into a pretty standard front harness. On your truck the front harness probably follows the same design as the gas engines in the fact that it runs from the right headlight area past the right side battery (only one on gas engines) back along the inner fender, through the firewall under the HVAC or heater case, across the dash and back out through the left side of the firewall and up to the left headlight.

Because of the design replacing it is a real pain.

[Gary Lewis]

Bill - I think that is 14401 and, as shown below, there is one specific to the diesel.  And I do not know what the differences are.

[ArdWrknTrk]

There seem to be a lot of differences in the cab/cluster wiring.
At least that's what I gather from seeing diesels listed on an entirely different page of the EVTMs.

[Gary Lewis]

Yes, there are apparently differences I’d not thought about. Like the glow plug light and switch.

But if no diesel harness is available then those differences could be accommodated.

[85lebaront2]

I imagine the reason for so many different harnesses is due to the continuous design, so any difference in cluster or engine results in a different PN.

[Danny Campbell]

Gentlemen, this is what I’ve hope for in having access to expert advice and instruction. Thank you for responding so quickly. 

I will review the documents in question and hope to provide some feedback soon. 

I did speak with American Auto Wire this morning and the 80-86 f series update harness kit is complete minus the secondary fuel tank harness. Scott at AAW said the update kit was for gas engines only (charging, ignition, fuel, etc), but did say it wasn’t impossible to adapt the kit for the diesel components as some have done with their universal harnesses. 

In the meantime, I will carefully remove the chassis harness from the cab as well as the glow plug relay and harness from the engine bay ascertain its condition. 

FYI, I’ve successfully removed a brake controller and aftermarket cruise control from the truck. The installation of these products have compromised some of the in cab wiring. The glow plug controller was bypassed for a push button setup. 

I’ve also attached a photo of the wiring on the passenger side fender, which I what has moved me in this direction to rewire the truck. 

Thanks for the help. 

On Mon, Mar 1, 2021 at 10:59 AM 85lebaront2 [via Bullnose Enthusiasts Forum] <[hidden email]> wrote:

I imagine the reason for so many different harnesses is due to the continuous design, so any difference in cluster or engine results in a different PN.

Bill Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F-350 460 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

---

If you reply to this email, your message will be added to the discussion below:

http://forum.garysgaragemahal.com/complete-wiring-harness-replacement-tp89782p89844.html

To unsubscribe from complete wiring harness replacement, click here.
NAML

[ArdWrknTrk]

Grrrr Scotch-Loc's and dollar store crimps....  

I can see why you might want to ditch it entirely but unless the insulation is crumbling you might be time and $ ahead just to un-screw it.

[grumpin]

An 88 F250 with the 7.3 diesel I used to own was at one point a wild land firefighting rig. A private contractor.

I wish I had a picture of the unused wiring I removed from that truck. I was able to clean up, repair and use the existing wiring.

At a later point I went through the glow plug system and got it functioning correctly. I’m not certain that the 6.9 and 7.3 glow plug systems are the same.

I would suggest before replacing harnesses, that perhaps you could straighten up what you have.

[Danny Campbell]

I was surprised that I was able to drive it home. I will attempt to trace and label the wires from the available schematics. 

It appears to use the same charging and starting components as a gas engine. 

On Mon, Mar 1, 2021 at 1:29 PM grumpin [via Bullnose Enthusiasts Forum] <[hidden email]> wrote:

An 88 F250 with the 7.3 diesel I used to own was at one point a wild land firefighting rig. A private contractor.

I wish I had a picture of the unused wiring I removed from that truck. I was able to clean up, repair and use the existing wiring.

At a later point I went through the glow plug system and got it functioning correctly. I’m not certain that the 6.9 and 7.3 glow plug systems are the same.

I would suggest before replacing harnesses, that perhaps you could straighten up what you have.

Dane
1986 F250HD SC XLT Lariat 4x4 460 C6
1992 Bronco XLT 4x4 351W E4OD
1998 Suburban LT K2500 454 4L80E
2000 Nissan Xterra XE 4WD 3.3 RE4R01A
Oregon

---

If you reply to this email, your message will be added to the discussion below:

http://forum.garysgaragemahal.com/complete-wiring-harness-replacement-tp89782p89854.html

To unsubscribe from complete wiring harness replacement, click here.
NAML

[Dan Crowley]

Hi Danny,  I too am restoring an 84 F-250 HD diesel 4X4 that I bought new.  I am not sure what condition my wire harness is in due to the fact that I know mice have been in there.  So thru my research I've found wire harnesses on e-Bay for about $250 that you don"t know anything about to one's from Painless Wiring which appear to be good quality but cost $1,500 to a company call Ron Frances Wiring, who also offers good quality wiring products for about $600 that I believe will work in our trucks.  Check them out on the web and order one of the catalogues, it has a lot of good information and tips on wiring vehicles. Good luck on your restoration.

 

[Danny Campbell]

Thanks Dan, I spoke with Ron Francis wiring and they informed me the harness they sale is exact replacement of the original chassis harness, but because the harness is designed for gasoline engines, they are uncertain that their harness could be reconfigured for the idi engine setup.

I’ve used the American Autowire update kit harness (which is a direct fit replacement) on a 78 f150 and is an excellent kit. So, I spoke with AAW and they said the same thing, that it was designed for gas engines only and had not heard of anyone adapting it for the idi Diesel engines.

In my research, I did come across one individual who successfully adapted the AAW update kit to work with his 6.9l idi. I’m currently in the process of removing all of the truck’s wiring intact, except were it has been damaged.

My plan is to purchase the $1500 update kit from AAW and reconfigure the engine setup for the glow plug relay and injection pump cut off. I will document everything and make it available  so others will have access to this upgrade.

[Gary Lewis]

Wow!  That's a lot of work, but your research will be invaluable to others.  Thanks for sharing - now and in the future.  

[85lebaront2]

The trick would be to take the relevant EVTM and start by going through the front end harness sections and comparing first connector numbers to see if the basic 14401, I believe, harness is essentially the same, I do know that the 1986 gas engine one is common to all from the 4.9L to the 7.5L as the EFI or Feedback carb systems are plug-in pieces.

I learned this when my son had a 1986 F150, 5.0L EFI and I had (and still do) a 1986 F350 7.5L carbureted with hot fuel handling package. fuel pump relay and inertia switch were identical, but the wiring layout to them was different, his being controlled by the EEC and mine by an oil pressure switch. Fuel tank electrical plugs were the same, his harness and mine were very different as his had 3 fuel pumps (2 in-tank and one on the frame) and mine just had 2 very low pressure in-tank pumps with a motor driven 6 port selector, his had the automatic switching valve/filter/reservoir on the frame.

[Gary Lewis]

True of '86, Bill, but for the previous years there were two different cab harnesses - with and without ammeter.  Ford did away with the idiot lights in '86.

[85lebaront2]

Gary, that may be true, but in posting that you confirmed my thoughts, that the cab harness is essentially universal other than the ammeter variable. The Diesel specific items are probably like the difference between EFI, FBC or DS-II/DS-III as each is essentially an "extension" of the cab harness to adapt for the specific powertrain.

[Gary Lewis]

Bill - I'm not sure I can agree as there were a lot of differences, although I don't know what they were:

[ArdWrknTrk]

It's a whole separate section in my EVTM.
But I don't know all the glow plug wiring and stuff.