Ford Truck Enthusiasts Forums - 1991 7.3 IDI to 7.3 PSD swap questions

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1991 7.3 IDI to 7.3 PSD swap questions

Hopefully someone can offer some useful advice or insight on dealing with the issues I'm facing.

We have a 1991 Centurion Classic C350 that originally came equipped with a 7.3 IDI diesel and E40D automatic transmission. For anyone who has never heard of these, it's essentially an F350/Bronco conversion, resulting in a four door Bronco on a 350 chassis. Pretty awesome machine, all told. The powertrain has been swapped out for a late 1994 Powerstroke diesel and manual transmission, including transplanting the entire 1994 wiring harness, in the cab and in the engine compartment. The full harness appears to be all there, but the in-cab part is quite a mess, with chopped off plug ends and wires dangling loose that have no logical application.

Most of the work for the transplant has been finished. The engine and transmission are in, it runs fine. The clutch pedal and other linkages have been installed and function correctly. All of that is not the issue. Mechanically it appears to be pretty sound. I may have to revisit some of that later, but for now it's all in there and working.

The 1994 wiring harness in the cab is a mess. I've spent several days screwing around with it, trying to figure out what goes where and getting everything to work, and then try to fit the dash in once it's all working. I'm tired of messing with it, plus I don't want to have to reinstall all those wires and controls back into the dashboard itself. I have decided to give up on the 1994 stuff and get something newer and more compleat, and that I won't have to re-assemble.

Today I picked up a mostly compleat 1996 dash assembly with wiring harness and controls all installed. All I have to do is bolt it in and plug it into the firewall harness. And then splice in three plugs from the old harness that were cut off. I have the plugs and can splice them in when I'm ready. That's not the issue.

However, what I'm noticing is that on the 1996 harness not all the wires going into the bulkhead plugs are the same as the wires on the 1994 harness. Most of them are identical, but there are a few that either have different colours, or go to different holes in the plug, or in some cases both. I'm assuming this is going to be a problem when I try to plug them in.

My question is, what do I have to do, to use the 1996 harness with the 1994 bulkhead plugs? I'm assuming I will have to make some kinds of changes to the bulkhead plugs, either on the dash side or on the engine side. If someone (or several someones) can tell me what to change, I will get right on it and get this thing installed and finished. Can any of you help me get this done?

Im no help on that but i think some pics are in order for that rig.

What dash are you intending to use? Do you have an 1991, 1994 and or 1996 EVTM?

Quote:

Originally Posted by madpogue (Post 14899432)

What dash are you intending to use? Do you have an 1991, 1994 and or 1996 EVTM?

I am intending to use the 1996 dash assembly. Does EVTM stand for Electronic Vacuum Troubleshooting Manual? I do not have one of those, but I do have a repair manual with diagrams for 1987 through 1996 F series trucks and Broncos. It has been exceptionally useful in tracking down some of the wiring issues with the existing system.

The 1991 dash has been removed entirely. I do not have any parts of it except some of the bezel and trim. Almost none of the 1991 wiring is still in the truck. None of the 1991 wiring harness or dash assembly was included when we picked the truck up, so I couldn't go back to the 1991 setup if I wanted to.

The previous owner removed all the 1991 stuff and replaced it with the 1994 Powerstroke stuff. Including the full dash assembly, wiring harness in the engine bay and cab, all the electronics, etc. I have all of those pieces, they're just a compleat mess and I don't want to screw around with them anymore. I'm tired of trying to reassemble it and then piece it back into the dash assembly. I'd rather just use a whole new setup that's already put together and all I have to do is install it.

To that end, I picked up a compleat 1996 dash with cab wiring harness at the scrapyard this morning. There is no difference between the 1994 and 1996 dash themselves, the only differences are in certain limited portions of the wiring harness itself. I will be using the 1996 dash assembly and wiring harness.

Where I'm running into an issue is the differences between the 1994 and 1996 firewall plugs. Of the two main plugs on each harness, they are mostly the same between 1994 and 1996. There are some minor differences in placement and colour of some of the smaller wires in each plug. I don't know what those differences signify or what I have to change, if anything, to safely mate the 1996 cab harness into the firewall plug to the 1994 engine harness.

And no, I am unable to swap the engine harness and firewall plug to a 1996 system. I do not have access to the rest of the engine wiring for the 1996 truck. The dash and cab wiring was intact on the donor truck, but the engine bay was totally stripped. There were no other 1996 Powerstroke trucks in the yard with intact engine wiring.

So what I need to do is make whatever alterations are necessary to mate the 1996 cab harness to the 1994 engine harness. I'm assuming I need to move some wires from their current pin position to a different pin position in either the 1996 plug or the 1994 plug. I'm cool with doing that, I just need to know what to move and where to move it.

I really don't have any help for you. But I'm sure someone here has some insight for you. All I can say is that thing is cool. I love the bricknoses and a centurion to boot. It doesn't even need to run and it would be cool.

Thanks. The truck actually is very cool. It looks good, it sounds good, and it's got everything we'd ever want. Should be good for a lifetime and lots of kids.

It's actually the missus' truck. We got it to replace her previous car, a 1997 Toyota Rav4x4, which was totalled last month when somebody pulled out in front of us and I couldn't avoid him. We miss that little car. Now we're down a car and it's really hurting us. We need this thing up and running.

For both of us, 4 doors and 4x4 were absolute demands. I won't accept a gasser, and she won't accept an automatic. I prefer fullsize trucks, she doesn't want a minivan or anything "soccer-mom-esque". I want a one ton suspension, she doesn't care as long as it drives nice. This thing has it all.

Four doors, 4x4, 1-ton suspension, turbo diesel, 5-speed, seating for 8 adults in comfort and safety, removeable top in the back, power windows and locks, a mild lift and decent tires, rear airbags, independent rear climate control... Yep, it covers all the bases.

That's pretty cool. Have you ever checked out the 4 door bronco forum?

Quote:

Originally Posted by MOOSE_MACHINE (Post 14899957)

That's pretty cool. Have you ever checked out the 4 door bronco forum?

Yep. Joined there too. Looking for answers. Hopefully somebody somewhere knows what I need to do to get this thing operational. There's so much knowledge and information in these forums... I'm not very good at searching, though, as I have been unable to find what I need. I'm sure it's been done before, but damned if I can find writeups on it.

I'm getting kind of frustrated. I've asked these same questions on several different forums, and so far I haven't gotten anywhere. We need to get this done, and my searches on the internet for the necessary information have been next to useless.