Wiring diagrams and descriptions of the various circuits seem to be a rare thing for Ford manuals - out of the 4 or 5 manuals I own for this era Ford vehicles, only one - the 1964 Comet and Falcon Shop Manual - has some decent wiring diagrams and descriptions, and even they have some odd head-scratching errors on them. I scanned them in at a pretty large size to preserve as much detail as possible and then scaled them down to half-size from there to make the "small" versions. Some details may be easier to make out on the large versions, so I've posted them in case they are needed. Also, I've grouped them by what they related to - in the actual manual these are interleaved together in various ways - so yes, the page numbers are out of order. If you want them in order, either buy your own manual or print these out and sort them by page number.
Here's a list of the errors - or likely errors - that I spotted while studying these diagrams and descriptions trying to figure out the wiring that was in the Ranchero.
Two Speed Wipers
Hand Drawn Complete Wiring Diagrams
Based on those diagrams, some stuff I downloaded off the 'net, plus some other wiring diagrams I have from other manuals, and the actual harness I removed from the Ranchero, I was able to put together a reasonably complete color wiring diagram for the truck. It omits the extreme front/rear sections of the harness because they're pretty simple and easy to understand in the factory diagrams. It is focused on a single page full color diagram for all of the wiring in the truck that attempts to show wiring in some rough idea of how they route in the actual vehicle, plus which connectors and wires go where. If I decided to do any changes, this is a great baseline for what should have originally been in the vehicle, and I can use it as a starting point for any updates. As long as I make an updated copy of the diagram with any changes I make, I'll have a complete wiring diagram for the truck for later reference. That will make solving any problems later on much easier, plus if I ever (gasp!) sell the truck or (more likely) need someone else to service it, I can give them the printout for reference.
I bought a set of used 1965 Comet interior and engine compartment wiring harnesses for $400 in hopes this would provide a better base to start with for my work. Unfortunately, no one reproduces the Comet harnesses, and although they are slightly better as a base to start with, it's hard to find good harnesses. My original Falcon harnesses were in about the same shape overall as the Comet harnesses I purchased - aka, not great. I did learn a lot about the wiring changes, though I'm not sure it was enough to justify the money I spent. It was a bit of an impulse buy. The big problem here is interfacing the wimpy stock wiring with the 93A GM alternator I installed - the amp gauge requires full alternator power to flow into the car, across the back of the amp gauge, and back out to the battery. And running 90A through the entire Comet harness is definitely not a safe thing to do. I was not counting on the Comet harness using an "inductive" style amp gauge - I thought it used the later Mustang-style gauge that has two small "sensor" wires that go out into the harness. Live and learn. Anyone need a 1965 Comet harness? It's checked, cleaned, re-taped, and has had the wiper wiring removed in preparation for a swap to delay wipers.
Falcon and Comet Firewall Disconnect Plugs
Because of the fact that the Comet has full gauges and the Falcon does not, there are some minor wiring differences and those differences affect the position of a few key wires at the main disconnect plugs at the firewall. The factory diagrams I had were very hard to read and compare on this detail, so I created my own and highlighted the exact differences they showed.
After doing this, I don't understand why Ford changed the location of the Starter Relay S Terminal wire between the 1964 Falcon and Comet harnesses. By swapping it between the disconnects, they caused a needless difference between the two harnesses. They could have simply run the ammeter battery connection using the same wire slot as the charge indicator light used, but simply extended it all the way to the Starter Relay B Terminal instead of connecting it to the regulator A terminal. By doing it the way they did, they caused both under-hood harnesses to be different. I guess the engine harness had to be different anyway to account for the fact that the oil pressure switch and sender used different terminals - the switch used a blade terminal and the sender used a threaded terminal similar to the ones on the back of the instrument cluster. Still, that's easily adaptable with a short adaptor harness on the engine itself, and it would have greatly reduced the complexity here. If they had made the changes in a more intelligent fashion and use an short adaptor harness for the oil pressure switch/sender, they could have prevented the need to create an extra harness. Creating and stocking an extra harness for no good reason is a waste of money and an annoyance for folks working on the cars. To me, this is just another example of how little actual engineering went into the wiring into the Ford vehicles in this era. It's just change for the sake of change.
Page last updated 01/02/2009 01:51:39 PM