Clean way for keyed power

85_Ranger4x4 · Dec 3, 2014

Been using those cheesy little fuse tap thingies that goes between the fuses and their socket. The PO started it to run the radio and I continued it for my additions but it has always bugged me. I can never keep it straight which one goes where and it looks like a hack.

I have mounted a second 6 slot fuse panel on the passenger side inner fender for constant battery like for lights but would like to do another for keyed power for the radio, fuel pump, tach, choke...

What is the "proper" way to tap into keyed power? All I want to do is get it to run something heavy duty like a starter relay to turn on the second "keyed power fuse panel" so I don't have everything running through my keyswitch, just the relay.

RonD · Dec 3, 2014

There really is no way unless you want to add a second key/switch.

But............the point of using a relay is so the amperage to power devices doesn't run thru a common switch.
The starter relay is a case in point.
Could you imagine the size of the ignition switch, and length of battery cables, if all the battery amps had to pass thru it to get to the starter.

So a remote switch/relay is used, these require under 1 amp to close and can pass high amps, a 30amp rated relay can safely pass up to 30amps but requires under 1 amp to close, a 60amp rated relay can safely pass up to 60 amps but requires less than 1 amp to close, ect........

So you are not loading up the ignition switch by adding relays.

If you are concerned about adding multiple relays then just add 1 relay to ignition switch and have that 1 relay power on all the other relays with direct battery power(fused of course), so you would only be adding maybe a .5 amp draw to ignition switch.

The EEC relay and Fuel Pump relay both get power when key is turned on, you could tap either of those to add another relay, coil power only not load power

85_Ranger4x4 · Dec 3, 2014

My tractors have push button switches that put full battery voltage to the starter. Have to file the contacts from time to time from the juice arching and pitting them. A keyswitch that could take that would be interesting indeed.

I just get tired of all the extra wires hanging out the front of my fuse panel.

My truck does not have an EEC or a regular power source for the fuel pump, originally it had an engine driven fuel pump, it's wire is one of those I am trying to get cleaned up.

All I have came up with so far is to just have one wire run a master relay (a second starter relay) like I mentioned, it would be nice to have one big one feeding a fuse block rather than 5-6 little ones with inline fuses scattered around the truck.

The bigger JD tractors use a "cab relay" which looks identical to the later Ford starter relays that has all the cab stuff come on with the key is where I got my idea.

RonD · Dec 3, 2014

OK, then you will have a ballast resistor for coil power, it should be on the fire wall, whiteish ceramic thing with 2 wires
With key on, one side of the resistor will show 12v the other side 7volts(approx.) that's the coil side.

Tap the 12v side(ignition switch) for relay power.
Benefit of using this wire is that it is OFF during cranking, it is only on when key is in RUN position, so anything on that relay can't draw power while trying to start engine.

Die.Fledermaus · Dec 3, 2014

What is wrong with using the ACC side of the switch? That would be my first choice to feed an inexpensive driving light relay into an aftermarket fuse block.

Doofy · Dec 3, 2014

How about a keyed, 30 or 40 amp master disconnect switch?

85_Ranger4x4 · Dec 9, 2014

RonD said:
OK, then you will have a ballast resistor for coil power, it should be on the fire wall, whiteish ceramic thing with 2 wires
With key on, one side of the resistor will show 12v the other side 7volts(approx.) that's the coil side.

Tap the 12v side(ignition switch) for relay power.
Benefit of using this wire is that it is OFF during cranking, it is only on when key is in RUN position, so anything on that relay can't draw power while trying to start engine.

Still using the stock 2.8 E coil so there is no resistor, but there would be keyed power there though.

Die.Fledermaus said:
What is wrong with using the ACC side of the switch? That would be my first choice to feed an inexpensive driving light relay into an aftermarket fuse block.

ACC of the keyswitch? I have Start, run, off and unlocked key for positions on my keyswitch.

Doofy said:
How about a keyed, 30 or 40 amp master disconnect switch?

I would rather not involve a second key.

Clean way for keyed power

85_Ranger4x4

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RonD

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