For now, I want them both on the same manual switch. Eventually I will get fancy and use one on a temp switch.
CK5
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'86 Jimmy 4in Lift, 40’s, tons, 8.1 Swap- 700r4 said PNNNNN
- Thread starter GWeakland620
- Start date
This is not a dedicated trail rig, but does trailer to the destination usually. I am currently in the planning phase of doing a 52/56" spring swap, and getting back to being more road worthy.
Use a relay or you risk melting your switch if it can't handle the amperage.
Jeeeeeeezzzzz... how'd I miss a conversation about me?!?!?
I'll get you a schematic. You'll need a couple 30amp fuses, couple 30amp relays and a switch.
Ok. Wires do work when they're connected to energy. It's like when you are pushing on something, but the electricity is doing the pushing. Wires connect the pushing thing to the thing that we want to push. In this case, it's a fan. You could turn the fan with a crank, but instead we're going to have the electricity turn the fan for us, so we can just drive without having to stop and turn the fan every few seconds. Would you like to have that? Or should we have you sit under the hood and turn the fan for us?
<wait for 3yr old answer, which invariably involves not sitting in the engine compartment>
Ok, let's have the electricity do the work for us. I can use this wire to connect the fan to the energy, and then the fan will turn itself. But electricity can only push in a circle, so I need to connect 2 wires. One wire for the electricity to push on the fan, and the other wire for the fan to push back. Because electricity needs a way back home at the end of the day when it's all done working. Otherwise it can't come home and have dinner and go to bed. Or wrestle with its kids. And that would not be fun. So electricity is like a big parade of working ants, all marching over to the fan. Each one gives the fan a crank and then goes back home because it is tired. So we have a bunch of electricities marching down one wire, turning the fan, and then marching back home through the other wire. We also need a stop light to tell them when to march and when to stop, because we don't want the fan always going. The fan only needs to turn when the truck gets hot, so we need a way to tell the electricities when to start turning the fan. We'll put a stop light in the wire to tell them. We call this traffic light a relay, because it relays the message to the electricities. So we will use one wire to connect the energy to the relay (the little stop light). Then we will use a second wire to connect the relay to the fan. And then we will use a third wire so the electricities can go back home. Then, when the stop light is green, the electricities will march around in their circle and turn the fan for us. So we can ride in the truck instead of sitting on the engine and turning the fan by hand. Now we need just one more thing. We need a way to turn the stop light on and off. So we will create a second circle for a second set of electricities, and these ones will turn the stop light on and off. It is just like the first circle, we will have a wire bringing the energy to a switch that will sit inside the truck, so we can turn it on and off. Then a second wire will bring the electricities to the stop light, which will turn on the much larger parade of electricities going to the fan. It's just like the light in your bedroom. You turn on the switch and the electricities start marching up to your light bulb and they make it bright so you can see what you're doing when you play with your Legos. Then when you turn the switch off they stop marching. We're going to do the same thing with the fan in the truck. When we turn the switch, the stop light will turn green, and the fan will start turning. All because an army of electricities started pushing on the fan. Does that make sense?
We might also have a second switch turning on the stop light. We could have a temperature switch that turns the fan on every time the engine gets hot. This would be just like the switch that we put inside the truck, we would make another army of electricities marching to the stop light. But this switch would be on the engine, and it would turn on whenever the engine got hot. Like the thermostat in the house, that keeps the house warm, but not too warm, all through the long winter. This one would keep the engine cool, but not too cool, whenever it got hot. We would set up the same 3 wires in a circle, just like we did with the other switch. And this one would also be connected to the stop light. So either the switch in the truck or the engine getting hot would make the stoplight turn green. And when the stoplight turns green, the electricities start marching to the fan. So either one would make the fan turn. And I think that's the end of this project. The fan now turns on when it needs to and turns off when it is not needed. Everybody is happy, and you don't hafta sit on top of the engine and turn the fan with a little crank.
That's my best attempt at explaining basic DC circuitry to a 3-year-old. Yes, the metaphors aren't perfect, and they don't begin to cover things like AC or RF or even more complicated DC circuits. But they are close enough to get the job done, with the simple low-voltage DC circuitry we're discussing. A good schematic is worth more than a word picture, and I only typed up what it looks like to have one fan and one speed. But the concept is the same even if you scale up the complexity.
I learned this stuff as a kid from a series of picture books like this one:
Ignore the big, scary words on the cover and the now-defunct branding. And the lack of an ISBN.
Books like this do a really neat job of explaining big concepts with little words.
I learned this stuff as a kid from a series of picture books like this one:
Ignore the big, scary words on the cover and the now-defunct branding. And the lack of an ISBN.
Books like this do a really neat job of explaining big concepts with little words.
I've already melted one lol.
I have a 90 amp relay, can I use that?
I'm pretty sure you can
A 90 amp relay will be fine for a 30 amp (max) load. It's overkill, kinda like using a Freightliner to haul your slide-in camper (coughWADEcough), but there are no downsides in this case.
Is it rated for continuous duty? You don't want a relay that will overheat during a 12-hour drive at 3.2MPH.
I like to wire switches and relays on the ground side. Positive directly to the load, that way the energy is spent before it reaches the switching device. Kind of like how an ecu doesn't typically control power, it controls the ground.
That's how my fans are wired, mostly because the temp switch grounds out at a certain temp.
Glad this came up because I didn't put much thought into it.
I think FiTech sends 12v so you might want to double check that. I had a BMW fan switch previously, new setup will be FiTech controlled with overrides.
Hurry up so I can copy it.
Unless its a Scout, then your hosedred is the positive, black is the negative
Or a triumph spitfire
Thanks for the help tonight. I have all but the ground at the switch and the fuse to wire in. I'll take some daylight pictures tomorrow. I went off the diagram that Mnstrburb posted, so I do believe it is switched power and not ground. I will be reworking these at a later date, to add a thermostatic switch, so I will correct it at that time. But for now it gets me going for the 19th.
There's nothing wrong with doing switched power. I've done a bunch that way.
