My 3FE into FJ40 swap

[Stumpalama]

You may be correct. My truck is an 8/80 build and is labeled an '81.
If you look at the later diagram for an FJ40 you will notice it doesn't have a main relay off the alt wire. That's not to say you can't use it though. I have to think about how the main relay would be useful.

 

[Stumpalama]

I'm still trying to understand the true purpose of the IG Main Relay. It's only real use for the 3FE is the powering of the thin B/L wire through the 7.5A engine fuse. This is covered in my diagram with the relay and fuse for the B/L wires.
Otherwise, just follow the instructions for converting your truck to an IC regulated alt.

 

[73tlcv8]

The 3fe alternator only needs two wires to it. One wire that is switched 12v to tell the alternator to excite itself. The other wire is the heavy wire to the battery. You will want to use the heavier wire from the 62 to handle the higher amperage. I used an aftermarket plug but you get the idea. The heavier blue wire is landed on the stud with the white wire to the battery. The blue wire provides excitation power to the alternator. The black/yellow wire is switched 12v. I also included a picture of the fusible links I make up at the battery end.

 

[Stumpalama]

Derrrr, I just realized you are swapping in the entire 3FE, not doing a 2FE and therefore will use the 3FE alt. @73tlcva posted the information you need to hook up your alt.

 

[Curtice]

I see a couple inconsistencies and wires to nowhere. Where does the power to your new relay to the BL wire come from? I'm posting some pictures of my wiring plan based on the FJ62 wiring diagram. Hopefully this can help. Based on the advice of an automotive electrical expert who reviewed my diagrams, I am going to swap out the fusible links for a 30/50A circuit breaker and run 2 10ga wires to feed the RY and big BL wires, unless I figure out that I could power these with a single wire to a fuse/relay panel to power these circuits. I'm just concerned about the electronic noise from the injectors etc. and this may necessitate running individual wires from the batteries.

Overview and written description of the wiring.

A closeup of the ignition wiring:

(k, finally getting back to this)

Stump - this might be a silly question, but after the relay, you have a 7.5a fuse only on the B-L wire to the ECU. Do the other BL wires not need a fuse (e,g, to the coil, injectors)? Or does the relay or fusible link perform this function? I guess this is a basic auto wiring question I am asking.

This is super helpful and I think I mostly understand. Am going to wire things up this way.

 

[sggoat]

First question. I have two sets of wires on the transmission. One is two wires with bullet connectors that I think is reverse light switch. But does anyone know what this other wire/connector is for?

First question. I have two sets of wires on the transmission. One is two wires with bullet connectors that I think is reverse light switch. But does anyone know what this other wire/connector is for?

Maybe the shift sensor?

 

[Stumpalama]

(k, finally getting back to this)

Stump - this might be a silly question, but after the relay, you have a 7.5a fuse only on the B-L wire to the ECU. Do the other BL wires not need a fuse (e,g, to the coil, injectors)? Or does the relay or fusible link perform this function? I guess this is a basic auto wiring question I am asking.

This is super helpful and I think I mostly understand. Am going to wire things up this way.

I will have to look at my diagrams again this evening.

 

[Stumpalama]

I rechecked my schematic and the 7.5A fuse protects the ecu input from the ignition switch. The rest of the B-L is 12V from batt, protected by fusible link. I am replacing the fusible link with a manual reset 50A marine circuit breaker near the battery.

 

[Curtice]

Awesome. Thanks. I have all the wires laid out how I want them. Next step is to get it in the vehicle and make sure I am good with lengths, then will start splicing where necessary.

 

[Curtice]

The 3fe alternator only needs two wires to it. One wire that is switched 12v to tell the alternator to excite itself. The other wire is the heavy wire to the battery. You will want to use the heavier wire from the 62 to handle the higher amperage. I used an aftermarket plug but you get the idea. The heavier blue wire is landed on the stud with the white wire to the battery. The blue wire provides excitation power to the alternator. The black/yellow wire is switched 12v. I also included a picture of the fusible links I make up at the battery end.


View attachment 899793 View attachment 899794

K, getting close...relay is wired up and other connections (NSS bypass, etc.)

A little more help on the alternator. I want to use the 62 connector, it is pictured below. It has 3 wires. Bottom left is the BY wire, top is a heavier white wire, and bottom right is a yellow wire.

1) I know the BY wire needs to be 12V switched. I think I saw that someone connected this to the + terminal on the coil. Will that work, or do I need to tap into another BY wire or something that is switched?

2) What do I do with the white wire? The schematic looks like this splices into the heavy white wire that goes to the battery. Do I do that?

3) The yellow wire...is this the wire that I run to the stud (the blue wire in your picture)?

Thanks!

 

[Stumpalama]

That white wire looks like it's been cooked. The B-G(?) Wire should be from your ignition switched power at run/start, IIRC.

 

[Curtice]

Tks. There is no BG wire. I think you are referring to the BY wire. That should be switched I believe.

White wire is just dirty. I think it's ok. But not sure what to do with it. I think splice into the heavy white wire. But not sure.

Also don't know what to do with the yellow wire.

 

[Curtice]

Wiring about there. I have the wires (unwrapped) in the 40 to test fit for length, etc. Once I get a few more things done, I think I will leave the unwrapped harness in, connect necessary stuff, and attempt to fire the engine up. No radiator hooked up yet, but I just want to see if I can get the engine to start and run for a few seconds.

I have a few more questions. These are the last of the wiring (I think/hope)

1) Still have my alternator questions above.

2) check engine light. I have a yellow/white wire that needs to go from the ECU to somewhere...what is the best thing to do with this? Do I need to install a new light, with some sort of power to it?

3) VSS. From this post (https://forum.ih8mud.com/threads/correct-speed-sensor-vss-info-for-3fe-swap.204049/), it says I should be able to use the VSS on my speedo. But I cannot find any terminals to hook it up. Does my speedo not have a VSS for some reason? Couple pics of my speedo:

 

[Curtice]

just bumping this up in hopes that someone has some thoughts on my questions. Thanks.

 

[73tlcv8]

1, the heavy white wire goes from the stud on the alternator directly to the battery through an appropriate fusible link. The stock 40 alternator white wire goes thru the ammeter in the cluster, but I don't think the 30 amp version will handle it. I didn't use the ammeter with the 3fe alternator.

The three wires in the plug are

white (S) - supply for excitation, this is equal to the blue wire in my picture, I tied to the stud on the alternator.
Black-yellow (IG) - switched 12v - I connected this to the engine fuse int he 40 panel.
Yellow-white (L) - to charge fuse/charge light circuit - I didn't use this - no connection.


2, CEL wire goes to a twelve volt indicator light, other side of light needs 12V source (ECU provides ground to make lamp come on)

3, that speedo doesn't appear to have VSS connections. There should be two screw terminals sticking out above the speedo cable connection. I found this image in another post.

 

[73tlcv8]

took a picture of my plug from the back.

 

[pappy]

2) check engine light. I have a yellow/white wire that needs to go from the ECU to somewhere...what is the best thing to do with this? Do I need to install a new light, with some sort of power to it?

The check engine light grounds at the ECU. Provide power from the gauge fuse to the light.

 

[rsnellie]

Mine runs great without the vss. I may be wrong, but I think the vss is only needed for the automatic transmission.


...via IH8MUD app

 

[pappy]

Mine runs great without the vss. I may be wrong, but I think the vss is only needed for the automatic transmission.

I'm not sure that is true. According to the 1988 Model New Car Features publication:

A check engine code #42 will occur if there is "No 'SPD' signal for 8 seconds when engine speed is between 2000 and 5000 rpm and coolant temp is below 176*F except when racing the engine."

That said, it seems there are folks out there not running a VSS with there 3fe/2fe transplants.

 

[Curtice]

awesome, thanks guys. I'll purchase a vss I guess. Rest of the stuff seems pretty straightforward now...very helpful.

I am getting close. These last few things were the remaining wiring I needed to do. Going to wire them up, then get other stuff hooked up like radiator and hoses. Then hopefully this will fire up!