Hello everyone,
*** SORRY IF THE POST IS LONG ***
I want to back track on the story of this truck just to see if it helps at all. I got a 1965 F250 i6 300 as a project truck to work on with my dad/give him a classic to drive back and forth to our town which isnt too far from our house, but as soon as I got it it's had a wiring issue. I drove it over some mountains from the place of sell, everything worked fine except the turn signal switch was kind of off and on and really hard to click down. After having it for about a month the switch (I assume OE given the plastic's state) quite literally crumbled away when I went to turn. Before this everything worked as it should, brake lights, turn signals, front rear, literally everything. So I buy a new switch, go to wire it in, truck sat for about a week while it shipped, then ever since I put the new one in I have this issue.

- No taillights working at all
- No brake lights working
- Front turn signals and headlights function properly

So I start digging through the wiring, find out some of the issue was caused by the connectors being stretched and needing bent back to make a full connection, so now I get some tail light life but its strange, now the lights work as follows

- No brake lights, no rear turn signals
- Tail lights still dont turn on with headlights
- Brake lights dont work still
NEW ISSUE
- If I press the brake AND use the turn signal the lights will come on as if I turned headlights on, flasher will "click" once and then not flash.
ITEMS I HAVE REPLACE: Turn signal flasher, Brake light SW, Turn signal switch x2 ( I heard sometimes cheap ones don't work well, still didn't fix my issue), brake light bulbs
Clearly this is a wiring demon that I will have to chase down I'm just hoping I can get some guidance on where to start or common areas where the wiring on these trucks is possibly faulty. I have the wiring diagrams printed out and have went over and cleaned all connections in the circuit aside from taking the fuse box off of the car and cleaning that (it is rusty, but testing w/ a test light seems to be getting decent power everywhere, probably corroded slightly since sometimes I have to scratch it with the probe) the wiring is also very simple, so I'm not too worried about going through it thoroughly. It does seem like people have been in thtere and made some weird connectons from PO's but, given that everything is working properly I don't think thats my issue, and looking at the wire colors it seems to be only related to a replaced IGN SW. II'm more confused that the issue only occured once the new switch was taken out, but also it is an old truck so I'm not surprised. Any help would be appreciated!

 

JLuna,
I would check my grounds. In 12v systems bad grounds can do funky things but there may be more.

 

oof that's not fun.
if ok to go through it thoroughly, maybe just pull the instrument panel, trace out all of the wires and make sure they are going where they need to go and are properly grounded. grounding issues can cause funny things. The brake lights are powered through the turn signal switch. I juiced mine with lectra-clean and functioned the turn stock a dozen times. ended up cleaning itself and the brake lights started working, even the blinkers.

Or, pull the wiring and go with a Painless Wiring harness.

start at the ignition switch, make sure it's getting consistent power in each position and go from there. follow the electrical flow path like its a river. start at the beginning. Good luck.

 

Based on your description, I agree you need to check your grounds. After those are clean and good, you can continue to trouble shoot if necessary.

Notice the wiring diagram doesn't show too many negative wires - mostly just positive wires. This is because The grounds are connected throughout the truck via the frame and sheet metal. All the ground "connections" need to be just as good as the positive 'connector' connections.
Grounds are often overlooked because they're not obvious like connectors and wires - but they do the exact same job and are just as important.
Some electrical components have a specific ground wire that is screwed against metal. Some grounds are just metal surfaces screwed tight against other metal surfaces.
For instance on my bed, the taillights are grounded thru the metal tail light bucket (not any wire). The back of the metal bucket is touching the clip nut, which is touching the sheet metal - The sheet metal screw is also touching the front of the bucket and touching the clip nut. The clip nut touches the sheet metal, then the sheet metal touches the frame, and ultimately up front the negative side of the battery is wired to the frame. This is the connector path.
If you want your heater blower to spin fast, and have bright lights, etc, etc, all gerund touch points need to be good.

The small areas where metal touches metal should be sanded or wire bushed to bright shiny metal.
Then put a light film of grease on the bright surfaces to prevent corrosion. (The metal will touch hard, and push the grease out of the way to make good electrical contact)
Re install and screw down tight. You can add star washers under the screw heads to help make a solid connection.

Since you're dealing with your lights, start there. Remove light buckets or ground wires. Clean the surfaces that touch, and re-install

Remove and clean where the battery ground wire lands on the frame.
Find, remove and clean ground wire connections between the frame and sheet metal and the frame and engine.

This can fix a lot of gremlins.

 

You may have ground problems but 99% chance the TS switch you have is no good, or you have it wired wrong. The ONLY switch to buy other than an NOS Ford is a Shee Mar. More Information for SHEE-MAR SM41F (rockauto.com)
Here is a wiring diagram 1965 Ford Truck Wiring Diagrams - FORDification.info - The '61-'66 Ford Pickup Resource
Here is a drawing I made when I was wiring my 79 column into the 65 harness if you can figure out my scribbles.

 

Okay so I will get to this around tuesday/wednesday, and hopefully reply by friday. As a note I don't have the original packaging but I'm pretty sure I have a shee-mar TSW? My first one the plastic is a different color, new one is the same coloration as shee mar and wires match the spots. It also came with a paper saying where each wire goes to fit the old wiring harness.

Next on the list, going through the grounds I'm pretty confident I can find those on my wiring diagram, but the ones mentioned as being two pieces of metal being pinched? Not sure where those are, can you elaborate more? Also I've had the buckets out but I haven't cleaned anything really, so I'll extensively clean everything and then lather it up in some di-electric grease before reassembly. Another question, should I take off my fuse box and clean that? It is partically corroded on the surfaces for some pieces, not sure if its a ground but I've seen other posts mentioning to clean that extensively.

Thank you everyone for replying! I will report back hopefully later this week with any good or bad results.

 

cant help you on the pinched grounds. but atlease test your fuse box. I had to clean mine up a bit for continuity. solved a few problems I was having.

 

Being pinched - I am essentially just calling out the places where things like the light buckets get sandwiched between a screw and the body or frame, and do not include a specific ground wire. The schematic will show a ground connection, but it's not necessarily clear how that connection is made. Here is a snip of the rear light bucket. The ground is made thru the bucket getting pinched under the attachment screw. Most items make there ground by being attached to the body or frame.

 

When I was having my turn signal and lighting issues, I bought two junk tss that had me questioning my sanity before i remembered Shee-Mar. I also found that the old wiring umder the dash had faded so much over the years that it was hard to tell what color some of the wires were. I ended up powering up each individual wire to see where it went. Lights have all been working fine once I finally got it all straightened out. And yes, went through all the grounds and even added a few.