I spent a few hours this morning dickin' around with my lights trying to figure how to hook-up a flat 4 connector. All the schematics I have show a "optional" trailer socket and Trailer socket chargeover switch which apparently I dont have. I tried hooking the tail lights to G as this supplies both RH and LH then GR for the RH blinker and GO for the LH blinker. I finally got the RH blinker to work but not the brakes....needless to say I'm feeling pretty useless right now and kinda have a feeling that I am totally missing something and it might have to do with the trailer socket charge over switch thingy...
yeah, you need a "tail light converter". There are various units on the market. I've never had one of the less expensive but brand name units last more than a couple of years.
I wired in a flat four pin trailer on my 10/69 1970 model FJ40 . I first undid what the original had done to the wiring to use a trailer. I then bought bullet connectors from Coolerman. Only current issue is the turn signal flasher is to weak handle the extra trailer light. Debating upgrading the flasher or finding LEDs for the trailer. The 70 is pretty close to stock including the paint so leaning towards LEDs. Since the stock tail light use the same lamp element for brake and turn signal no converter is needed. Even if I was using seperate lamps on the trailer I wouldn't use a converter. I would tap into the front turn signal power under the hood and get brake light power under the dash to keep it simple. My 70 is not in town but can get you what wires I used in a week or so.
Can't recall where I posted it, but I posted a circuit diagram to all of the conversion using relays. It also puts the tail lights on a relay. That takes all of the trailer light's load off the original circuits and only adds the tiny load of the relay coils.
Put the circuit in it's own thread: https://forum.ih8mud.com/trailer-te...nverter-circuit-using-relays.html#post9047418
I did something like twenty years ago but the other way. I had the tail lights so they would work off the vehicle power or to a trailer plug to operate them from the vehicle towing it. Didn't use a relay but a triple pole double throw switch. Installed the switch in a 2X4 rain tight box mounted on the passenger's fender. Tapped into the wiring at the plug on the firewall. Not a big fan of mounting any switch or relay in the back end of a FJ40 because everything is exposed to the weather. Only place in the back that is weather tight is inside the cab which wouldn't be that clean a look especially on a stock vehicle. I do think it is funny all the wiring diagrams for late sixties early seventies all show the option trailer light switch. No clear diagram showing how it wired without the trailer plug. Personally if you going to switch from the vehicle light to the trailer lights your going to want to have the switch right by the plug so plug it in and throw the switch. Even then you could for get. I think keeping it simple is best. I only tow small military trailers with my FJ40 so really not to much extra load on the wiring. Now if you towing a bigger trailer with a bunch of lights like some travel trailers I won't just do a switch but relays that take all the load except the relay coil off the factory wiring.
I too tapped into the wiring at the plug on the firewall. I installed a "power" tail light converter in the glove box to protect it from the elements. I ran a 5 lead flat wire to the back of the Fj40 and mounted a connector to the bottom of my MAF-1045 bumper so that it's up and out of harms way. The 5 wire was used anticipating adding a flood light or two to my trailer.
I know what your saying about using relays. On the pre 74 only three relays would be needed because the tail still used the same bulb for the brake/turn signal on one element and tail light on the other element on a dual element bulb just like the trailer. I'm not a fan of mounting anything that might need trouble shooting or repair underneath the vehicle. Not that big a deal if you can rinse off first then use a creeper on a concrete floor. On the road repairs usually aren't the clean. For this reason I would mount a relay box under the hood and run wires for the trailer lights from there. The FJ40 wiring is pretty simple up to the early seventies. If you can find a extra male and female plug you can make a adapter and not cut into the factory wiring. The FJ40s are going up in value so I'm not doing anything that could hurt that value like cutting into factory wiring. This location is also right by the battery which is where you would want to get the power from anyway. Just your running three or if you running a ground from the battery four wires instead of just a single power wire. Probably go this route on my 68 FJ40 which is been modified with a four speed and later buckets. Along with my FJ62 it is used to tow my M101A1 around my cabin. Just by the nature of how I use as a dump trailer it is more likely to have wiring problems. My M416 I went thru the wiring and replace the tail lights with new military lights, my MBT I completely rewire with 14 gauge wire and used new Military lights. This includes running a ground wire back to the tail light housings. Not worried about any ground or short issues with those two. On my FJ62 I mounted the conversion box inside the weather tight left fender well. Easy excess by removing the rear window washer bag. One thing that I don't think was mentioned was use a relay that plugs into a base and be sure to use all the same relays for easy trouble shooting and repair. They is one option I have thought about that would place the conversion under the vehicle. This involves stripping the trailer conversion out of something like a early Tundra. This would include the a section of the wiring harness around the conversion box. Once wired to the vehicle's wiring harness from then on it would just be a matter of plugging in another box if problems arise. I haven't checked but guessing the Tundra is getting old enough to show up in pick and pull yards.
I guess that I failed to mention that you can see and reach that box from the rear bumper.
Just scored a Toyota branded bracket that holds a flat 4 rubber connector only. Originally it was wired to a plug that plugged into the rear harness of a 2001 Tundra. All looks to me like it might have been a factory accessory sold and installed as part of or after the vehicle sale. Would be worth looking into for the OP.
I guess that I failed to mention that you can see and reach that box from the rear bumper.
Just scored a Toyota branded bracket that holds a flat 4 rubber connector only. Originally it was wired to a plug that plugged into the rear harness of a 2001 Tundra. All looks to me like it might have been a factory accessory sold and installed as part of or after the vehicle sale. Would be worth looking into for the OP.
I bought a used 2001 Tundra back in 2004. Had a receiver hitch from another Tundra I owned. Bought everything I needed from Toyota to install factory trailer wiring (four pin). I believe it took about four parts. One being hard to find a dealer who was able to find the part number for it. I wondered why Toyota didn't offer this as a kit. But I guess most wouldn't being willing to pay what it cost and would just as soon have some trailer shop cut into their factory wirings to save some money or figure install the factory wiring would be over their head. I believe the cost was around $200 but it was very easy to install. It was all plug and play. Included a fuse that connected to the battery, the wire with connector was right there to plug into the fuse holder. In the back the plugs needed were already. They were plugged into dummy connectors that secured the wiring up out of the way and kept the end of plug clean. Since there was fuse added I have to believe the trailer lights are on there own circuit. The convertor was a small sealed cube which has to be solid state. My thought is you can find these in a junk yard. Toughest part would be to figure which wires are what in the vehicle wiring harness. Guessing on my early cruisers I could just not wire up the brake wire and the turn signal wires would do what was needed.
My FJ62 is using one of those factory brackets you scored. My is off a early 100 series Land Cruiser.
I redid the trailer plug on my 70 FJ40 a few days ago. First picture is of the stock wiring. The black tape is where I repaired where the original owner had cut into the factory wiring. Two open connectors one is a solid green double female bullet which is tail lights. To the right of this is another open solid green single female bullet connector which is also tail lights. The other open connector in the center is red with a blue strip which is the reverse lights. The turn signal/brake lights have a bullet connection in the center of the rear sill. Those were green with a yellow and orange strip. Didn't pay attention to which was which. Just moved bullet connector around until it was all correct on the LEDs on the plug. Second picture is the U-Haul plug and mounting bracket I used. The third picture is of the old connector (short one) I mounted last year as temporary mainly to check out the wiring. The longer plug is the new one plus the double female to single male I made to plug into factory wiring fort the turn signal/brake lights. I bought the connectors from Coolerman here on Mud. Fourth picture is finished for now, may seal better later. Fifth picture is how it looks from the back. It also shows the plug the original owner drilled a hole in the rear sill to mount.
Here in what I did last year to my FJ62. This replaced the round six pin plug I used that match the one that was on my 68 FJ40 forty years ago when I bought. That too was mounted with a hole cut in the rear sill. The wiring is spliced a couple of inches away from the plug and upgraded to fourteen gauge. Still using the converter I installed twenty years ago but if I can the factory convertor at a junk yard I will change over to that running a separate fuse power wire from the battery. Find a second one and replacement would be a simple plug in. This would still be installed inside the driver's rear fender well. I prefer to have anything that might need service to be in a dry clean location. The back underside of a vehicle is one of the dirtiest locations on a vehicle.
The wiring is spliced a couple of inches away from the plug and upgraded to fourteen gauge. Still using the converter I installed twenty years ago but if I can the factory convertor at a junk yard I will change over to that running a separate fuse power wire from the battery. Find a second one and replacement would be a simple plug in. This would still be installed inside the driver's rear fender well. I prefer to have anything that might need service to be in a dry clean location. The back underside of a vehicle is one of the dirtiest locations on a vehicle.
