Wycked- I figured it was too late for you, but I posted it anyway because I thought it was some really good tech for others in the future.

Privateer-don't worry too much about hijacks. I originally started this thread just for random stuff, so your questions are fine. If it were me, I would keep all the wiring 78 and then just add what I need from the 89. For example, it will need a bunch of efi stuff, but you can probably make it stand alone, and then just add in the minimum, such as keyed on. I wouldn't make 2 harnesses into on big *******ized one; I would keep the older stock one and just add in a few plug-ins. I think you only need the efi and electric fuel pump. Other than that, everything else should be 78

Hopefully someone else can add to that if they think there's more.

 

Thankx for you response Teds74, but I definetly need to clarrify the situation a bit before I lead you'all on a goose chase. I know the purists won't like this but I like a lot about the 89s dash, radio, heater controls and gauges are easier for me to see and use. My fab skills are strong and I can graft the above into the 78 and have it look quite well. Where your thread has helped so far is that it has shown me the right way to splice in things like my lights. Where I think I'm going to need help may be in seperating the ignition switch from the steering column and putting it in the dash and hooking up the starter contact on my clutch. I should be able to do the conversion from lever to slave fabrication plus this is pre ABS so that means the brake system won't be a problem.
My brother is a 35 year Ford mechanic who is good at it, but he doesn't mix and match parts, and he gives vague answers thinking that I never left the trade. We're some what estranged but starting to communicate again. I'm going to be using this truck to pull an 5th wheel RV for 50,-70,000 miles over 3 - 4 years, by which time I should be pretty much toast. I know some of the above is TMI, but I figured you should know why I'll be doing somethings differently. Thank you all for the help you've allready supplied just by having this thread.

 

Great thread!! I already wanted to make a soldering jig, do the 3g upgrade and was planning on maybe doing an electric fan. Now I want to do the H4 halogen upgrade, I have some pretty decent lights now but WOW the improved night vision would be amazing. Thanks for the links as well some great info all the way around and resources for some hard to find pieces. I do have one quick question while we are at it tho. I plan on completely rewiring my sound system again but instead of just hard wiring it (and if i change it and need to change the harness to the back of the radio, lose more wire etc) does anyone offer a type of plug/block/harness that i could use sorta like what newer vehicles run. I would love to make my own harness that could be unplugged instead of having to cut and splice.(I.E. a block for the speaker wires and one for power/ground. or an all in one.)I hope that makes sense haha.

 

I used bullet connectors for mine so I could theoretically take it out if needed. Other than that, I guess you could buy a generic connector, but then you just have a plug in front of a plug (the stereo one) Not sure what that would gain you.

 

So I have been reading about the fan upgrade, fog lights, and other add ons. People say just find a "key on" or power. So my thinking you can't just have a bunch of things on one wire. What is the correct way to wire in fog lights KC lights and fan and cab lights? I really want to do it correctly and not a hack job. Not that I plan on ever selling my truck, just want to " Do it right the first time, and be done with it."

 

I agree. That's why in my 75 supercab I added a couple of 6 circuit fuse blocks; one as a HOT fuse block and another for Keyed Ignition under the dash since my OEM fuse block had only 5 or 6 circuits. I don't plan on running anything that takes alot of amperage, but for basic things I have it covered. Plus, if running an electric fan and KC lights, you'd need to use relays anyway. Here is the schematic on what I did to add power distribution. I will eventually add a higher amperage alternator like a 3G, but for now I'm only using a couple fused circuits for a radio, brake controller, electric choke and another 12V power source for electronics. I used 10 gauge wire to feed since my fuse blocks are rated at 100 amps. I could have used a higher amped relay, but again I'm not adding "heavy power" so a 40 amp relay is plenty for my application for the keyed ignition fuse block I added.

 

For the keyed relay on the bottom of Bucks drawing, you could pull from this plug

I am not 100% sure you would need a fuseable link, but you can buy those in a stretch of wiring, or, if you're like me, poach one out of my spare ford wiring box

 

Ya, probably wouldn't need a fusible link for the keyed ignition wire to the relay since the relay is taking all the power for distribution to the fuse block and I do think I actually omitted that when I wired it up, but didn't take it out of my diagram. I don't think it would hurt by any means. Originally, I was thinking I should put one there since i had fusible link wire to spare.

 

One suggested improvement to buck's drawing (inline with ted's thinking) is that you don't need a fusible link coming from the fuse box to the coil (pin 86) of the relay, if the hot-in-RUN trigger signal is already protected by the fuse box.

You also can reduce the wire size going to pin 86 (currently shown as 10 AWG) because the only current that will flow through this wire is the coil current of the relay (much smaller). 18 AWG is plenty and will be much easier to work with. The heavy load current only flows through the contacts (pins 30 and 87). When you hear 20, 30 and 40 amps with regard to relays, it refers to the contacts.

Other than that, great work, very clear and useful.

EDIT: sorry buck, looks like you already said some of that. It took me some time to type this

 

Sorry for a delay in the repost hope it isnt too far down hah. I'm not really familiar with "bullet connectors", what do you mean by them? And I have not been able to really find any generic connectors I may not be looking in the right places though. My gain is that I am notorious for changing my stereo out more often than most and more often than needed just because I either get tired of it or it isn't what I want after all. If I had a plug other than the stereo one to unhook this would allow me to change the stereo harness outside the truck at my own pace without disturbing the radio in place just in case I don't get around to doing it at one time. Main reason for this is that (at least last time I knew unless something changed) Different stereo manufacturers make different plugs for the backs of their stereos and if I need to change it I have to keep having to cut and splice in wire. I could get another half of the said plug and wire in the new stereo harness and not have to cut out any wire. Hope any of that made sense haha.

 

Thanks for the suggestions. Your right on the downsizing on the wire on the 86 pin. I'll probably just leave it alone in my truck since I already used it, but I will change things on my diagram just so others can see and use it for reference.

Just to add, the fuse blocks I used cost around $18 a piece so for the blocks, wire used, relay, connectors, etc., I have less than $45 I think in the addition compared to the time and cost of trying to upgrade the original harness fuse block.

I also took a electrical grounding terminal block that you can get at any hardware store that is used in electrical panels and screwed one into the firewall on the inside and ran a ground wire from the negative battery cable to the ground terminal. That way I have a nice and clean grounding block on the inside that I can use for additional grounds rather than using screws under the dash. It wasn't necessary, but I had the small grounding block. Since these pics, the wiring has been straightened out so it doesn't look like a spider web under the dash. Just thought I'd show what kind of blocks I used. Just so it wasn't too crowded by the original block, I added the HOT block by the OEM block and then the Keyed ignition on the other side side above the foot pedel.

 

Okay Buck, that helps a lot. I have a ground block just like that in my misc parts. I grabbed a fuse box from a Windstar when I did my 3G. Still need to get a mega-fuse holder. And really need to get a soldering gun and wire and connectors.
Then I'll be dangerous haha.

 

78 Custom, bullet connectors:
http://ecx.images-amazon.com/images/...500_AA300_.jpg

Good points on the electrical relays. To expand a little bit, a relay is like and electrical switch, um, switch. It only needs a small amount of current to close the big switch, which allows larger current to flow.

If you think about the starter solenoid (which operates similar to a relay) the leads from the ignition switch are really small, but the starter motor wires are huge.

 

Exactly. Here is a pretty good article that describes how relays work.

http://www.autoshop101.com/forms/hweb2.pdf

 

Need a little help.

I have a 78 F250 supercab 4x4 XLT with factory Dana 60's, AC, tilt. I'm wondering if anyone knows how many of these were produced with these options. X26 VIN.

I've owned two F3 4x4 1979 F350's that were original, found that around 700 of those were made. I wondered why I've seen several of those in WA state, found out they were produced in CA but only shipped to WA and TX.

thanks