Wiring dual electric fans with relay and toggle switchElectric fan relay
Posted 12 June 2016 - 07:20 PM
Posted 12 June 2016 - 10:56 PM
How do you have the connections setup on the relay? It sounds like you have an unswitched positive wire hooked up to the trigger terminal. They should be wired as follows:
30: Positive wire from battery. Fuse should be in this wire between the relay and power source.
86: Trigger. This will be the wire coming from your switch. This should only get voltage when your switch is on
87: Output. Positive lead that runs to what you're powering. In this case, it's the fans. Both of them should be hooked to this wire if you want to power them with only one relay.
87A: Unused in this case
The fans being grounded like you have them should be fine.
Edited by calZ, 14 June 2016 - 10:10 AM.
Posted 13 June 2016 - 05:36 PM
Posted 13 June 2016 - 05:52 PM
Posted 13 June 2016 - 07:23 PM
Posted 14 June 2016 - 10:14 AM
You could test if your switch is bad by just using a wire from the battery to 86 if you have it wired like I posted above. Below is a diagram that's probably easier to understand.
Posted 14 June 2016 - 02:43 PM
Posted 14 June 2016 - 03:09 PM
Is the switch wire just connected back to itself inside that shrink wrap? You have to have the other end connected to the battery.
Posted 14 June 2016 - 04:28 PM
Posted 14 June 2016 - 04:37 PM
Posted 14 June 2016 - 04:55 PM
If it's connected to itself it isn't switching anything. It should go battery -> switch -> relay.
Posted 14 June 2016 - 05:25 PM
Posted 14 June 2016 - 05:55 PM
There is a direct connection from the battery to terminal 30. There is a switched connection from the battery to terminal 86. You can get battery power from the same wire and then split it before it gets to the relay and switch. Let me try to explain it again.
30: Positive wire to the battery.
86: Wire from 86 to one side of the switch. The other side of the switch should go to a power source. Some people use the ignition so the fans can only be turned on while the key is on. The simplest way is probably straight to the battery.
87: Wire to positive side of fan
Edited by calZ, 14 June 2016 - 05:56 PM.
Posted 14 June 2016 - 06:19 PM
Posted 14 June 2016 - 06:20 PM
Posted 23 June 2016 - 10:27 AM
Good job guys,
Just as a refresher as this does give some people trouble.
Generic automotive relays usually have 4 pins.
30: Usually 12 volt power. Straight from the battery. This is going to power your accessories down the line, put a fuse that is slightly above the max operating amperage to protect the circuit from drawing too much power.
85: Ground. This is for the relay. This gives the differential for the relay so the relay can work. Sometimes it can be used as a switched setup by putting a switch inline if you have a constant 12 volt signal source. Usually I route this one straight to the mounting screw used to hold the relay.
86: Signal. This is to signal the relay to turn on. Usually a 12 volt source. You can use a toggle switch between this terminal and the battery, but be careful that means that one side is going to be hot all the time. Ideally taken from ignition, fuse box any other triggered 12 volt source. Ideally you DO NOT want this to be constant as that means you can leave it on accidentally.
87: Output. This will be 12 volt power to the accessory. This will take power from terminal 30 when the switch signal is tripped. This will go to the +12v side of the accessory and the accessory.
Sometimes you will run into an 87A: this is usually on 5 pin or 4 pin relays that are AO, always open. That means that the power from 30 will always be going to 87A, until the relay is switched via 85/86 at which point the relay will stop providing power.
Also there are a couple ways to run this setup. You can put an inline switch from the 12 volt source. You can put an inline switch to the ground. You can put a switch on the ground side of the accessory.
Most diagrams I have seen are wired with the 12 volt signal wire being switched. The only time I have had to wire a relay with a switched ground was the fuel pump from megasquirt, which the signal wire controls the ground circuit instead of the signal circuit. I'll leave it to someone smarter then me to explain the difference.
You can use redundancy for the trigger signal which is usually a good idea. Using an ignition source on top of a trigger is a good idea. My friend's nitrous setup was wired to have a master toggle, a WOT switch and tied to the high beams. You had to have all three conditions met to run nitrous, that meant no one would kick it on accidentally.
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