Field relay in 68 f350

[BigIron]

I've got a field relay that plugs directly into the wiring harness of my 68 f350 390. It now has a broken terminal from my attempt to remove it for cleaning. No good deed goes unpunished. This truck also has a transistorized voltage regulator that also nicely pigtails into the harness. Besides the textbook response from the 68 manual, what does the field relay do and are replacements available? I've stumped all the parts stores in town and can't seem to locate one through the online catalogs. Any info will be greatly appreciated. I am new to the resto game and electrical is by far my weakest subject.

[Thunderfoot]

Are you referring to the one for the alternator that is in this wire diagram??? http://www.fordification.com/tech/wirin ... ging03.jpg or was it the horn relay? http://www.fordification.com/tech/wirin ... ircuit.jpg

If it was for the alternator you should be able to get a "12V relay" to replace it... It is just a standard 12V activation relay, it will have 4 connections 2 which are for the Main loaded power and 2 which are for the activation of the relay. If you look at the diagram wires 4 and 904 are for the activation of it and wires 26 and 152 are the main load that is being switched on from the activation.

[BigIron]

Sorry for the late response, out of town for a few days. It is the alternator field relay with 4 prongs. I was able to solder the one broken prong back on but doubt the longevity of that fix. I will continue my search this week for a replacement. The horn relay survived my cleaning efforts. Thanks for the help, this site is great!

[basketcase0302]

Could you post a picture of that "field relay". owned Ford trucks for many years never seen one in the charging circuit. Sure it isn't the horn relay?

[fordman]

its a field relay in this diagram. i have never seen one myself. but they do show them for the F350 trucks. http://www.fordification.com/tech/wirin ... ging03.jpg

[BigIron]

My 68 manual has the schematic and drawing of the field relay like every one should have one. I'm assuming they were paired with only the transistorized voltage regulator which is also some what difficult to find. The field relay is about twice the size of the horn relay. I'm still in the dark ages without a digital camera and paying dearly for not taking enough photos.

[basketcase0302]

fordman on Wed Aug 17, 2011 5:17 pm
its a field relay in this diagram. i have never seen one myself. but they do show them for the F350 trucks. http://www.fordification.com/tech/wirin ... ging03.jpg

Wow, once again I learn something everyday! It has five wires going into it looks like, and your voltage regulator is mounted onto the radiator support? Very different for sure, (instead of the voltage regulator mounting onto the PS inner fender).

[BigIron]

This corner of my truck was wrinkled up bit by my brother who liked to consume too much barley pop, so unsure of where the voltage regulator bolts to. Once again I am paying for not taking enough pictures. Had to buy a new inner fender for the starboard side, there are no corresponding holes for the the voltage regulator. The way the wiring harness lays down naturally, it appears that the regulator wants to lay flat on the inner fender with the radio suppressor through one of the three bolt holes. The field relay looks like it wants to mount on the vertical wall of the inner fender aft of the starter relay. There is still one wire I have left to figure out on that side near the battery. It appears to be black with a red stripe and has connector crimped onto it that would mount to a small bolt like terminal. Thanks for all the help!

[BigIron]

The radiator support is still laying on the shelf waiting to be mounted. I'd better do that next and maybe the mounting of the wiring harness will make more sense. The schematic in this thread shows it on the radiator support, unfortunately my Marine buddy with short term memory issues disassembled that corner of the world.

[fordman]

on all of the non filed relay trucks i ever seenthe voltage regulator has been mounted to the core support.

[basketcase0302]

There is still one wire I have left to figure out on that side near the battery. It appears to be black with a red stripe and has connector crimped onto it that would mount to a small bolt like terminal. Thanks for all the help!

When I look at the diagram again, it shows wire #4A dead ending? Maybe a ground? Black would be a typical color for a ground wire.
Maybe Shayne or someone else can pipe in here to help soon.

[Thunderfoot]

The Black/red striped wire is a ground wire, it is used to ground the alternator with the voltage regulator and the field relay, it is wire 26 in that diagram. That ring terminal is to mount it to one of the mounting bolts for the Voltage Regulator.

[BigIron]

I believe the forum has solved most of my current electrical questions. I am still amazed that the field relay is that rare of a beast. I am going to use my repaired original version until I can locate one to replace it. Once again, thanks for all the help. I can't wait to get back in the driver seat of this hunk of iron. Very few of these crew cabs left. I'll catch up with technology and post some photos one of these days.

[basketcase0302]

Very few of these crew cabs left. I'll catch up with technology and post some photos one of these days.

Aha...now you tell us your working on a crew!
You deserve this...