What is best way to tap 12v ACC for multiple items/relays on FJ40 (1 Viewer)

[Last Flight Out]

Been wondering about this one - with our vintage glass fuse/boxes - what is best way to tap at the fuse box for accessory (switched) for say multiple relays for external lighting? I am thinking like a mini waterproof bus connector inside engine bay or under dash - with single tap into one of the fuses. Is this the best way to go? Just trying to find cleanest and easiest way to do this. TIA.

 

[B y r o n]

Go to your local auto parts store and ask where their "AGC Glass Fuse Tap In Adapters" are.

 

[45Dougal]

Personally I'd tap a new waterproof fuse box directly into the battery connector to power things like extra lights, and just use the ACC to drive the relay coil.
This way you avoid putting even more load through the ignition switch.
The radio feed is a handy tap to drive just a few relays via switches on the dash.
The IGN feed at the regulator is also handy (especially if you now have a regulated alternator) but again not for big power.
I avoid touching the original fuse box which is only held together with luck.

 

[1911]

Been wondering about this one - with our vintage glass fuse/boxes - what is best way to tap at the fuse box for accessory (switched) for say multiple relays for external lighting? I am thinking like a mini waterproof bus connector inside engine bay or under dash - with single tap into one of the fuses. Is this the best way to go? Just trying to find cleanest and easiest way to do this. TIA.

I installed an auxiliary fuse block with an integral switchable relay in mine to power ham and cb radios, GPS, fridge, etc. I came directly off the battery and only tapped the stock fuse block for an "on with ignition" signal. I put mine in a Con-Ferr tool box inside the cab (behind the seats), but you could also put in a waterproof box in the engine bay as @45Dougal said.

 

[Last Flight Out]

Go to your local auto parts store and ask where their "AGC Glass Fuse Tap In Adapters" are.

That's not going to work as 1) the cover will no longer fit with several wires into that tap and 2) will overload the box.

 

[Last Flight Out]

Personally I'd tap a new waterproof fuse box directly into the battery connector to power things like extra lights, and just use the ACC to drive the relay coil.
This way you avoid putting even more load through the ignition switch.
The radio feed is a handy tap to drive just a few relays via switches on the dash.
The IGN feed at the regulator is also handy (especially if you now have a regulated alternator) but again not for big power.
I avoid touching the original fuse box which is only held together with luck.

Thanks man - that is what I will do. Cheers.

 

[zerotreedelta]

All depends on your needs - if doing a bunch, it's probably worth doing a separate box.

For light duty or one or two things, Uncle Toyota did hide two spade taps on the back of the factory fuse box, covered in shrink tubing. One is switched, one is constant feed...I don't recall if they're pre- or post-fuse, it's been a while.

EDIT: for what it's worth, using the factory tap would be a decent way to trigger a heavy duty relay to drive an ACC block for the secondary fuse box.

 

[Last Flight Out]

Personally I'd tap a new waterproof fuse box directly into the battery connector to power things like extra lights, and just use the ACC to drive the relay coil.
This way you avoid putting even more load through the ignition switch.
The radio feed is a handy tap to drive just a few relays via switches on the dash.
The IGN feed at the regulator is also handy (especially if you now have a regulated alternator) but again not for big power.
I avoid touching the original fuse box which is only held together with luck.

@45Dougal - whipped up a quick & basic schematic. Check my architecture here....but I think this is correct. I am wiring up some LED ditch and fog lights.....so low draw on power....but assume one relay can power a secondary fuse box with fuses for each set of lights. Dont think I need any more relays in this setup.

 

[45Dougal]

@45Dougal - whipped up a quick & basic schematic. Check my architecture here....but I think this is correct. I am wiring up some LED ditch and fog lights.....so low draw on power....but assume one relay can power a secondary fuse box with fuses for each set of lights. Dont think I need any more relays in this setup.

View attachment 3275468

Sure, you can do it that way, but your 30A relay will be unprotected by a fuse unless you add one up stream. It will also be active continually whenever the ignition is on, regardless of whether your switches are on.
Alternatively you could feed the new fuse box directly from the battery (keeping the unprotected cable as short as possible).
Each switch would then be fed from the ACC and drive its own (lower power) relay to switch the load from the new fusebox. This uses more relays obv, but they're only active when you switch stuff on.
Depends what you're adding. If it's a few heavy loads then probably nicer my way. If it's a lot of smaller loads like leds then your architecture makes more sense.

 

[wimberosa]

@Last Flight Out Definitely interested in path you take and diagram you eventually decide on. I'm in somewhat of the same ballpark on this question.

BTW...if anyone knows any good tutorials in this area...I would appreciate pointers. This probably seems simple as hell after a few minutes of study...but am not sure of a good starting point to get that study.

 

[ToyotaMatt]

Been wondering about this one - with our vintage glass fuse/boxes - what is best way to tap at the fuse box for accessory (switched) for say multiple relays for external lighting? I am thinking like a mini waterproof bus connector inside engine bay or under dash - with single tap into one of the fuses. Is this the best way to go? Just trying to find cleanest and easiest way to do this. TIA.

the BEST way is to create a T double connector at your green key switch 4 pin ones

i do this often for folks

its SAFE secure and SOLID

oem fit form function

- then the ACC 10ga wire can be a home run to yoor new feed B+ location of choice

i read all above posts

some are hoky , others would work

- this way is a solid bet to be best

 

[45Dougal]

the BEST way is to create a T double connector at your green key switch 4 pin ones

i do this often for folks

its SAFE secure and SOLID

oem fit form function

- then the ACC 10ga wire can be a home run to yoor new feed B+ location of choice

i read all above posts

some are hoky , others would work

- this way is a solid bet to be best





View attachment 3276417

You prefer to run additional loads directly from the unfused ignition switch?
Maybe I misunderstand.
I'm worried about the integrity of the white/blue wire connections after 45 years, so I prefer to avoid loading it further where possible.

 

[ToyotaMatt]

You prefer to run additional loads directly from the unfused ignition switch?
Maybe I misunderstand.
I'm worried about the integrity of the white/blue wire connections after 45 years, so I prefer to avoid loading it further where possible.

Ok ..,

I see .,

Let me clarify in. a different technical way :

- FJ40 ignition key switch circuit has 4 Leads

- the white wire w / blue tracer stripe is NOT incoming from fuse box , it comes From fusible link

- your ACC circuit is blue wire w / red tracer stripe from key switch to those circuits

- you would create a splice point at the green. 4 pin connector at key switch using a male and. Female same locking connectors and the blue wire w/ red tracer then has a 2nd lead 10ga gauge wire to be krystal Klear here to home run it to your new junction block / secondary fuse box assy. It then services how ever many smaller fused circuits u are planning ….

- I have created a Same in kind set up using a 2nd OEM toyota glass tube fuse box mounted exactly the same on the RH upper kick panel
And gets B+ feed using my above tech .

I call it a HIS and HERS factory siamese fuse boxes set up ..

- I actually ran both a ACC blue with w / red tracer & a black wire w / yellow tracer key ON. Position home run 10GA gauge leads so I could have both those options available in my Siamese factory 2nd fuse box option I pipe dreamed up …

- see …

That was a few years back before LEDs bulbs and when it was HIP to have a big speaker carpeted BoX behind both front seats and a AMP sandwiched under the passenger Seat above the fuel tank armor plate sheet metal cover .

- I had created a late model non-USA sound system Kustom set up

- In the late 40 series non-USA far away you could get a 4 speaker Audio. Option

The driver side above the fuse box is the only un-used void space on a 40 so a 2nd factory Speaker was added there

Then little self contained plastic box ones we’re mounted in the void space in the corner what side marker lamps are behind the roll bar

The box has a tab with one big hole same size as the main 14mm roll bar bolts it affixed there ..

Along with the seat belt lap belt mounting tab ..

I liked adding little fused circuits via the 2nd HERS Siamese factory fuse box option I had conjured up ..

Toyota never did this …

But I cloned the 4 speaker Audio set up 83 and 84 models right from my SOR paper parts category.

They bragged about it in there little Land Cruiser museum in the front show room parts counter they have or had ?

I would brag about that too , it was so dam kool ..

 

[45Dougal]

Ok ..,

I see .,

Let me clarify in. a different technical way :

- FJ40 ignition key switch circuit has 4 Leads

- the white wire w / blue tracer stripe is NOT incoming from fuse box , it comes From fusible link

- your ACC circuit is blue wire w / red tracer stripe from key switch to those circuits

- you would create a splice point at the green. 4 pin connector at key switch using a male and. Female same locking connectors and the blue wire w/ red tracer then has a 2nd lead 10ga gauge wire to be krystal Klear here to home run it to your new junction block / secondary fuse box assy. It then services how ever many smaller fused circuits u are planning ….

- I have created a Same in kind set up using a 2nd OEM toyota glass tube fuse box mounted exactly the same on the RH upper kick panel
And gets B+ feed using my above tech .

I call it a HIS and HERS factory siamese fuse boxes set up ..

- I actually ran both a ACC blue with w / red tracer & a black wire w / yellow tracer key ON. Position home run 10GA gauge leads so I could have both those options available in my Siamese factory 2nd fuse box option I pipe dreamed up …

- see …

That was a few years back before LEDs bulbs and when it was HIP to have a big speaker carpeted BoX behind both front seats and a AMP sandwiched under the passenger Seat above the fuel tank armor plate sheet metal cover .

- I had created a late model non-USA sound system Kustom set up

- In the late 40 series non-USA far away you could get a 4 speaker Audio. Option

The driver side above the fuse box is the only un-used void space on a 40 so a 2nd factory Speaker was added there

Then little self contained plastic box ones we’re mounted in the void space in the corner what side marker lamps are behind the roll bar

The box has a tab with one big hole same size as the main 14mm roll bar bolts it affixed there ..

Along with the seat belt lap belt mounting tab ..

I liked adding little fused circuits via the 2nd HERS Siamese factory fuse box option I had conjured up ..

Toyota never did this …

But I cloned the 4 speaker Audio set up 83 and 84 models right from my SOR paper parts category.

They bragged about it in there little Land Cruiser museum in the front show room parts counter they have or had ?

I would brag about that too , it was so dam kool ..

So the answer is yes.
You prefer to run additional loads directly from the unfused ignition switch.
As I said, I'm worried about the integrity of the white/blue wire.
Maybe yours is in better condition than mine

 

[B y r o n]

O.K., it took a little time for my old brain to kick in. I forgot about these two power taps already on the fuse block. Take a look at post #7 in this thread.

Pick up power off the battery or secondary fuse box and trigger it with the switched power lead.

 

[zerotreedelta]

Kinda funny, I added a photo above in post 7 of this thread (above), and they're mentioned in that thread on post 7 as well.

If one needed a lot of draw, that aux blade would work good to trigger a large relay (like the 30A) referenced above to drive a secondary fuse box, and a fusible link to feed the power side of the relay would work nicely, similar to how OEM feeds the main fuse panel.

 

[red66toy]

Relays should get their juice directly from a fused battery or added power distribution box. However, for switching them on and off, using the ignition switch like @ToyotaMatt suggested is a good one. Relays take like 0.1amps or less to switch, so triggering a few relays from the ignition switch is not a big deal at all.

 

[Last Flight Out]

Sure, you can do it that way, but your 30A relay will be unprotected by a fuse unless you add one up stream. It will also be active continually whenever the ignition is on, regardless of whether your switches are on.
Alternatively you could feed the new fuse box directly from the battery (keeping the unprotected cable as short as possible).
Each switch would then be fed from the ACC and drive its own (lower power) relay to switch the load from the new fusebox. This uses more relays obv, but they're only active when you switch stuff on.
Depends what you're adding. If it's a few heavy loads then probably nicer my way. If it's a lot of smaller loads like leds then your architecture makes more sense.

@45Dougal I like this idea better as I dont want constant power until a switch this closed.....not sure I can do a split for the ACC 12v for both relays....but see what you think.

Im only driving 2 LED spot lamps and 2 LED backup lamps....I assume a 20A relay for each is plenty. But correct me if I am wrong.

 

[zerotreedelta]

Super lazy edit, but typically you'd want to put the toggle switch on the "signal" side, and not the load side. It's also frequently more common to switch the ground signal to the relay instead of the 12v, just as a ground wire is safer to run to the switch than the hot. They're generally a four terminal block - solenoid ground, solenoid 12v, 12v supply, and 12v load.

Alternatively, you could put the toggles in each leg of the green "ACC" line headed to each relay.

It's not on the diagram, but you'd likely want a section of fusible link between the battery and the new fuse box.

 

[45Dougal]

Super lazy edit, but typically you'd want to put the toggle switch on the "signal" side, and not the load side. It's also frequently more common to switch the ground signal to the relay instead of the 12v, just as a ground wire is safer to run to the switch than the hot. They're generally a four terminal block - solenoid ground, solenoid 12v, 12v supply, and 12v load.

Alternatively, you could put the toggles in each leg of the green "ACC" line headed to each relay.

It's not on the diagram, but you'd likely want a section of fusible link between the battery and the new fuse box.

View attachment 3277997

Exactly what he said. I wouldn't bother myself with a FL tbf, it's belt and braces.
Hmm not sure that translates in US English? :/