I have a question around the wiring of relays and basic electronics. I'm looking to convert the acc power plugs in my 4th gen T4R to a switched always on mode. I have read about pulling the relay and rigging up a bypass wire to the high current side of the relay to make it an always on circuit. My question is can the trigger side have multiple +ve sources without adding diodes so that the relay works as it is currently with an additional +ve power source that I would have on a switch.

Basically what I was looking to do:
1. Find a constant power source, tap the circuit with a 1amp fuse
2. Run the wire to switch mounted in one of the blank slots(diff lock location)
3. Continue the wire to the relay for the acc plugs and solder it to the +ve side of the trigger side of the relay and put the relay back in.

This would all be easier if I didn't have to pull the relay and rig up wiring for diodes from the trigger on the relay and the switch. If this has to be done my first thought would be to:
1. Pull the relay
2. Wire up the High side directly from the box to relay
3. Wire up the low side +ve with a diode to the relay
4. Wire the switch with a diode to the +ve to the relay
5. Wire the low side -ve directly to the relay.

The introduction of the diode seems like alot more wiring than without the diode....so do I really need the diode? Or is the diode needed to prevent something bad on the low side circuit and the one that I tap into?

Thanks

 

On my 3rd gen the +ve side of the trigger comes from the ignition switch, so if you wired that to another +ve source you could turn on some other circuits on the ignition. That could cause problems when you turn off the truck, if the new switch is still on, like turn off the ignition and the engine keeps going. You'll want to put the diode on the original +ve source, the one from the ignition, to prevent power going down that wire to the ignition switch.

I would think 4th gens have the same wiring setup.

 

for some reason my 94 pu is already a constant power source. dunno how it happened, but im certainly not complaining.