1978 FJ40 Random wires/bracket (1 Viewer)

[lofty25]

Hi - New here but have found the forums super helpful as I dive into my 1978 FJ40.

Background: My dad bought it a few years before he passed and just drove it, didn’t make any changes to it. I’ve had it parked for 10 years, couldn’t let it go even though people would stop by or put offers in my mailbox to buy it.

Recently moved it into the garage, changed fluids, drained/added gas and she fired right up. Clutch plate was “frozen” but found some fun guidance on here that did the trick and took it for a spin. Goal is to just get everything working correctly and slowly make improvements.

Have a few questions I haven’t been able to find answers to and hoping others that are more knowledgeable might be able to help:

1. Passenger side on the firewall there is a bracket next to the heater blower that isn’t used. I’ve seen other 78’s that have something mounted there but don’t know what is missing. There isn’t an empty plug from the wiring harness so not sure if it’s missing something or not.

2. Passenger side towards the front by the negative battery terminal there is a WB wire that isn’t connected and a BY wire that isn’t connected. Is the WB just a ground that should go to frame or battery? Any idea where the BY wire goes? I don’t see any other wires in that area that have that style of plug.

On the coil there is a single blue wire that runs from it to the ground inside on the fuse block. The connection on the fuse block is broken, it still ran so is it truly needed? Clearly this was something the PO did but I don’t know why or what purpose it serves.

Thanks!

 

[1911]

Hi - New here but have found the forums super helpful as I dive into my 1978 FJ40.

Background: My dad bought it a few years before he passed and just drove it, didn’t make any changes to it. I’ve had it parked for 10 years, couldn’t let it go even though people would stop by or put offers in my mailbox to buy it.

Recently moved it into the garage, changed fluids, drained/added gas and she fired right up. Clutch plate was “frozen” but found some fun guidance on here that did the trick and took it for a spin. Goal is to just get everything working correctly and slowly make improvements.

Have a few questions I haven’t been able to find answers to and hoping others that are more knowledgeable might be able to help:

1. Passenger side on the firewall there is a bracket next to the heater blower that isn’t used. I’ve seen other 78’s that have something mounted there but don’t know what is missing. There isn’t an empty plug from the wiring harness so not sure if it’s missing something or not.

2. Passenger side towards the front by the negative battery terminal there is a WB wire that isn’t connected and a BY wire that isn’t connected. Is the WB just a ground that should go to frame or battery? Any idea where the BY wire goes? I don’t see any other wires in that area that have that style of plug.

On the coil there is a single blue wire that runs from it to the ground inside on the fuse block. The connection on the fuse block is broken, it still ran so is it truly needed? Clearly this was something the PO did but I don’t know why or what purpose it serves.

Thanks!

1. That is where the stock voltage regulator was mounted. Guessing that your truck probably has a later or aftermarket internally-regulated alternator.

Do you have a factory service manual with the fold-out wiring schematic in the back? Would probably help you. I'd look at mine for you, but it's packed away.

 

[zerotreedelta]

That's likely for the "maintenance interval detector" (P/N 89445-22010), used with a two-piece speedo' cable. Guessing yours was removed and flipped to a one-piece speedo cable. It'd trip the EGR light on the dash based on distance...what interval, not sure.

(EDIT, at least on a '76...may be different for a '78.)

 

[Cruiser Cult]

 

[Cruiser Cult]

This is from our 78 FJ40, "Kyle".

 

[zerotreedelta]

Ha...they moved things around between 76 and 78. The regulator on the 76' is on the driver's side.

 

[Cruiser Cult]

Regarding the wires: that blue one isn't stock. There are two wires from the igniter that attach to the two terminals on the coil. The hanging white wire with the ring terminal may need to go to the alternator, but hard to tell from that angle. There is a good wiring diagram at Coolerman's site. This one is for the 78 http://www.globalsoftware-inc.com/c...ics/FJ40/1978FJ40/1978fj40_wiring_diagram.pdf

 

[sggoat]

White W/Blk stripe is always ground-
The larger yellow wire you show is prob a body-to-frame ground
The larger Blk(yellow stripe) is from the IG terminal from the igntion sw. to the ignitor(it has a pigtail spliced into it that goes thru a resistor then the pos coil connection, continues to a condenser to ground. The By you show with a butt connector goes nowhere(on my 77--I don't have the condenser)
The blue wire is a mystery--if connected to the coil negative, it should be blk and go to the ignitor.

I have FSM wire diags for 1977 and 1979, but no 78. I do have a 78 from the Haynes manual.
I can try to scan and attach -- hope this helps--

 

[zerotreedelta]

I happen to have the factory '78 book (simplified)...in case it helps.

(Download image/zoom in as needed)

 

[lofty25]

First, thanks to everyone for all the helpful responses and links to documentation. I'm probably getting in a little over my head with this project but not ready to part with it until I give it a serious try. I will continue to research, learn and probably ask stupid questions when I get stumped. Hardest part so far is trying to figure out what previous owner did and why they did it.

1. That is where the stock voltage regulator was mounted. Guessing that your truck probably has a later or aftermarket internally-regulated alternator.

Honestly I have no clue and can't read anything off the alternator. I will try to find some images of stock to compare it to.

This is from our 78 FJ40, "Kyle".

Ha...they moved things around between 76 and 78. The regulator on the 76' is on the driver's side.

Where was it mounted on the 76? This is mounted on the driver side to the right of the steering column which looks similar to the picture @Cruiser Cult posted of Kyle. The mounting bracket is the same two bolt pattern as the bracket on the passenger side but it's mounted directly to the firewall here. Is this something different?

 

[zerotreedelta]

That's about where it is on my 76, and the wire colors look to be the regulator wires from my recollection. White+red, white+green, white+black, giving you sense, field-energize, and ground to the regulator.

Mine was the more boxy variant, shaped like the one pictured on the '78, but on the firewall on the driver's side below the brake master. It was replaced at some point, but my wiring and mounting was original.

 

[ToyotaMatt]

First, thanks to everyone for all the helpful responses and links to documentation. I'm probably getting in a little over my head with this project but not ready to part with it until I give it a serious try. I will continue to research, learn and probably ask stupid questions when I get stumped. Hardest part so far is trying to figure out what previous owner did and why they did it.


Honestly I have no clue and can't read anything off the alternator. I will try to find some images of stock to compare it to.

View attachment 2938913





Where was it mounted on the 76? This is mounted on the driver side to the right of the steering column which looks similar to the picture @Cruiser Cult posted of Kyle. The mounting bracket is the same two bolt pattern as the bracket on the passenger side but it's mounted directly to the firewall here. Is this something different?

View attachment 2938915

27020-61013


27020-61023

 

[DickM]

Are you sure your mystery blue wire was connected to the fuse block? It could have been an aftermarket tachometer feed. Can't really think of anything other use for a wire to the coil negative side.

 

[fyton2v]

On my 78, the stripped wire coming off the harness next to the coil (with the female end) goes nowhere. The blue wire connects to one of there terminals on the coil, but mine is on the other terminal. Not sure it matters. The white wire looks like a ground. I have a ground in that same area that is a little different. It's two wires and it goes to ground via a bolt on the bracket that attaches the coil to the fender well.

 

[KeilOver]

@lofty25 is your alternator on the driver's side?

 

[KeilOver]

On Kyle, the alternator is on the passenger side, that spot was where the smog air pump used to live. Here are some better pictures of the coil and igniter before I refreshed the engine bay.