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Yes, it was used to tow trailers as it has both a serious receiver hitch as well as a 5th wheel setup. So, it might be to parallel batteries. But, did Ford sell a kit for that? It sure looks like it has factory connections.
And, while I was poking around under the hood I found something with which I need some help. I'm pretty sure the Trailer Lights Relay and the Marker Lamps Relay are the two in the housing screwed to the firewall, and the Fuel Pump Cutoff Relay is the one hanging in the breeze. (I don't really know where the fuel pump relay is supposed to go, but that's no biggee.) But, what's the solenoid? The EVTM's show a junction block there, as shown here in the 1986 version, but it is the same in the 1985 version. So, I first thought it was an add-on. However, the wiring doesn't appear to have been hacked and the wires are a perfect fit to it. Further, the small yellow wire with the 90 degree boot sure looks stock.
Anyone know? What am I missing?
Gary, by the length of available wiring, it looks like the Fuel Pump Cutoff Relay ["hanging in the breeze"] with its plastic "Christmas" tree mount could plug into the small hole of the inner fender area between the lug wrench and the firewall.
David - Well spotted! I'll check after I finish the second cup and see if you are right, but I'll bet you are.
In the past day I've learned some things about the EVTM. One is that it doesn't provide all of the wiring options available on these trucks. For instance, I can't find the auxiliary battery relay in any schematic, nor is there an auxiliary battery for the gas engines. So, I don't know how that relay is wired - yet. But, Vernon also supplied me with the wiring diagrams so I should be able to tell from them.
Second, the EVTM doesn't put all the info about things that take up the same physical space in the same spot in the book. On Page 107, below, it shows the fuel pump relay going in a cover on the firewall. But on Page 14 it shows the marker lamp relay going there - without the cover. And on Page 130 it shows the trailer lights relay going there - again without a cover.
But, what do you do if you have all three? Big Blue shows that the trailer and marker lamp relays win and get housed in the cover, and apparently the fuel pump relay gets stuck on the fender. I assume that spot is recessed enough under the lip of the fender to provide some protection.
To compound it a little further, if you have a DRW model, the trailer and marker lamps relay are the same piece, marker lamps (fenders) are fed with the trailer tow harness that runs down the frame alongside the rear harness.
Don't mind the "rat's nest" that was my stop & turn relays along with a battery charge relay.
Yes, there are apparently lots of variations that the EVTM doesn't show. Or, if it does it has them scattered such that you can't easily find them.
Just had a thought - that relay cover (E3TB 9C392-A2A) would make a neat housing for headlight relays.
Also, I'm going to have to check Big Blue's top for signs of marker lamps. He has the relay, and it is possible that was put on all F250's or maybe just the HD's, but that doesn't seem like something Ford would do.
The cab roof lights were not fed with that relay, only the dually fender lights, cab roof lights were on the parking/running light circuit. The marker lamp relay and trailer tow relay are the same part, since Big Blue has most of the trailer tow option parts (if not all) I suspect that is what is there.
On the battery relay, it looks to me that someone added that using the Ford dual battery setup as a pattern, I would look for where the output terminal from that goes, probably to one of the terminals on a trailer socket.
Bill - Did you happen to wire this thing? You are spot-on as the output of the relay goes to one of the two 6-pin trailer sockets. However, the socket is surely mis-wired as the output of the relay comes in on the tail/running lights pin instead of the 12v pin. Oh well, both 6-pin sockets appear to be mis-wired so there will be a day spent figuring out what I have, removing one of them, and soldering/shrink-wrapping all of the insulation-displacement connectors.
Anyway, after checking things out under the hood I turned the key to Start and got nada. Several times. Until one time it spun and started. So I took a look at the solenoid. Yuk! Guess I know what I need to do next.
Looks like my 58 starter relay used to get, rusted at the terminals. I used to keep a 1/2" wrench in the glove box so I could loosen and wiggle things till it would start.
Yes, I'm peeling the onion, for sure. Kinda fun, for a while. I've always liked fixing things, and these are, for the most part, easy fixes. It'll get old pretty soon. However, this truck has really good "bones", so it will be worth it.
Want a laugh? Today I followed a skinny red wire from the negative battery post into the cab. Turns out it is the ground for the voltmeter. Yep, he ran the ground all the way from the battery, but got power from inside the cab.
The auxiliary battery relay doesn't pull in, but if I replace that I might use the output of it to supply the voltmeter until I install a second battery. You reckon it is big enough to carry that voltmeter? Talk about overkill, but it is a handy source in a convenient location.
As for the solenoid, not only are the cable connections suspect, but that ground screw looks dodgy as well. I don't think the ground was the problem today as I could see the voltage drop when I turned to Start, and since the fuel pump drops out then (that's right folks ) I'm pretty sure the solenoid itself came in but the connection to the starter was bad.
Gary,
What kind of connector do you intend for trailer wiring?
Will you be using a brake controller?
I ask because I'm pretty sure I have a Ford trailer harness in one of my totes of truck stuff.
This plugs in at the back of the drivers side frame rail and the taillight harness plugs into that plug. It has a heavy fabric sleeve and FoMoCo engineering number.
Jim - I am interested! That would save me from having to cut and solder several places where the original harness has been hacked. But, I don't need a pic as I'll trust your word. PM me regarding the cost.
As for the trailer connector, I hadn't thought about it. But, I will be using a brake controller so the connector will probably be the round 6-pin one. In fact, there are two of those on the truck and one is very new-looking, so I might as well use that. However, I might be better off to buy a new 7-pin connector like my 2015 F150 has from the factory. That would standardize my fleet, and I already have the 7-pin to 6-pin adaptor since I had to have it to tow Bruno's trailer.
And, speaking of brake controllers, do you have the male connector, or connector and wiring, that connects a controller to the harness near the brake pedal? I'm going to install a Tekonsha Prodigy like I have on Rusty, but would like to connect it to the truck's harness neatly.
Talk about overkill, but it is a handy source in a convenient location.