What's a good 12v switched source underhood? (1 Viewer)

[dogfishlake]

Hey all, I'm wondering what would be an appropriate place to pick up a switched 12v source in the engine compartment to power my relay that activates my water/methanol injection system? It would be o.k. if it powered from the key being on accessory and ignition, but II would be best being powered on ignition only. Thanks in advance

 

[dogfishlake]

Forgot to mention, it's a 97

 

[george_tlc]

Well, if you want something that is +12V *ONLY* while the engine is actually running (actually alternator is up and producing charging current to the battery), then you can splice in at the fuse box on the DS fender to get what I call Alternator Good. I use that signal to activate a small relay (the typical 12V 40A relays) that powers a large solenoid to charge my aux battery. I'm not sure how much current that signal can provide, but certainly enough to energize the above mentioned style of relay. This has worked for me for 15+ years.

cheers,
george.

 

[NLXTACY]

There is not 12v ignition hot in the engine bay but @george_tlc suggestion is pure genius. I will be utilizing.

 

[dogfishlake]

There is 12v ignition hot in the engine bay but @george_tlc suggestion is pure genius. I will be utilizing.

I will probably use @george_tlc suggestion too but for curiosities sake, where is the one you were thinking of?

 

[dogfishlake]

Well, if you want something that is +12V *ONLY* while the engine is actually running (actually alternator is up and producing charging current to the battery), then you can splice in at the fuse box on the DS fender to get what I call Alternator Good. I use that signal to activate a small relay (the typical 12V 40A relays) that powers a large solenoid to charge my aux battery. I'm not sure how much current that signal can provide, but certainly enough to energize the above mentioned style of relay. This has worked for me for 15+ years.

cheers,
george.

That's great, thanks!

 

[NLXTACY]

I will probably use @george_tlc suggestion too but for curiosities sake, where is the one you were thinking of?

Ugh, I mistyped. It was supposed to read NOT under the hood. I'll edit my post. Sorry. I blame interpretive text.

 

[dogfishlake]

Ugh, I mistyped. It was supposed to read NOT under the hood. I'll edit my post. Sorry. I blame interpretive text.

Check

 

[landcrshr]

There is not 12v ignition hot in the engine bay...

???

There is the EFI circuit.

 

[toyotaspeed90]

There is also the coil/ignitor... (which is powered by the efi relay.... I assume toyota used the same name in the FZJ80 but I all 4 cyl cars they named this the circuit opening relay, or COR).

You could also jump off the fuel pump, which would purely be when the engine is in its initial start or actually running....

 

[dogfishlake]

I wondered about the coil, didn't think about fuel pump. I wasn't sure if I'd be messing with the coil function, but being power to a relay, it's really minimal. Got a say, I like the fuse splice, neat and clean

 

[loucaojr]

Hi,

I was wondering if the FZJ80 doesn't have a fused power outlet like my HDj80, it could be a good source!

Cheers

 

[george_tlc]

No - there is no such fused outlet on the petrol version, at least not the US spec one...

cheers,
george.

 

[loucaojr]

OK, that's pretty handy!

Cheers