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5-Pin Changeover Relay 40A 12V


This is 1x relay.


This is a brand new 5 pin 12V 40 Amp solenoid/relay.

It is a high quality unit specifically made for JTX. What sets this apart from our old relays is this has a green LED light which comes on when it is activated. This makes it so much easier to see that it’s received the signal to be on. That makes life a lot easier when fault finding like why are lights not working – well the green light is off so that means the relay is not being turned on. Or it can be very handy in your custom projects to display the relays so that you can readily see what’s on and what’s not on. Also the clear cover lets you see the workings inside and you can work out how it works and actually watch it switch on and off. Pretty cool little unit if you ask me.

The purpose of a solenoid is to provide heavy wire high amp power direct to an application such as high wattage lights without having to carry such high power through switches or original wiring that can not take such loads.

Here are some common uses ..

  • You want to replace standard 65W light globes with much brighter light globes (say 100W or 130W). You can use the original light wiring to trigger the solenoid to power up the new heavy wire that runs from battery to lights.
  • You just want your lights to be brighter. Light duty wires experience a voltage drop and the power at the light is not as good as it could be. Gains of up to 20% extra light can be achieved by powering heavier wires from battery to light, triggered by the solenoid.
  • You want to run driving / spot lights on the roof or bull bar. The lights can have maximum power yet triggered by hi beam on the indicator stalk to come on with high beam and turn off automatically when you dip your lights. This is actually a legal requirement for setting up spotties. That trigger wire can also have an inline switch on the dash board so as to have hi beam with or without the spotties coming on.
  • You want to run anything else that requires heavy duty power but triggered on and off by light duty wires and switches at the dash board
    • Air Compressor
    • Camp lights
    • Horns
    • Pump / camp shower
    • Thermo Fans
    • Fuel Pumps

You need to keep this law of physics in mind: Watts = Volts x Amps or you can change the look of this same formula to … Watts / Volts = Amps. In your case 65W globes divided by 12 Volts = just 5.4 Amps. Or more importantly, 2 x 130W globes (260W) divided by 12 Volts = 21.7 Amps.  The vehicle manufacturers simply dont allow for 20+ Amp loads in your factory wiring. The great news is this solenoid is 40 Amps so it’s only at half it’s rated ability when running 2 x 130W globes. In fact this solenoid can manage anything up to 480W.

The one solenoid can run 2 x spotties or 2 x Hi Beam wires.

If you want to run 100W low and 130W hi (both are much higher than factory) then buying a second solenoid is recommended – 1 for low beam and 1 for high beam.

Make sure the wires you use from Battery to Application (Lights) via the solenoid are rated to well above 25 Amps. The heavier the wire the better the power.

For the majority of mechanics out there who dont know how to wire up spotties (dam there’s a lot) it’s a magic black box that just works. But, how do they really work? When current passes through wire it emits a radiation/magnetic field that circles the wire in a particular direction. Get a lot of wires together and that field gets stronger. Then run those wires into a circle so that field is made heaps stronger by being added to from all sides and now focussed up the centre of the circle. Inside the solenoid is a coil of light duty triggering wire. That coil is the circle and when you turn it on it creates a magnetic field up the middle that controls a switch that switches the heavy wire on. It’s that easy.

I have attached some wiring diagrams so you can see different ways this can be wired up.

  • 86 Trigger wire – light duty is OK.
  • 85 Earth for relay – light duty is OK.
  • 30 Power from Battery – Normally heavy Duty and fused.
  • 87 Target Application – Only powered when triggered (common).
  • 87A Alternate Application – Only powered when not Triggered (not common).

There are 2 x output pins – 87 (outer) and 87A (inner)

  • When not triggered power passes through to 87A – often referred to as “Normally Closed”. When triggered 87A is disconnected (switched off). It’s a “turn off” relay to 87A.
  • When Triggered power then goes through to 87 – often referred to as “Normally Open”. When not triggered 87A is off. It’s a “turn on” relay to 87.

Some vehicles such as 80 series landcruiser have negative switching. That is, the power is always on at the high beam and by earthing the light turns it on. In such cases you would wire up the solenoid so that both headlight wires are the triggers for the relay and don’t earth the relay to the car. If those 2 wires make the headlight come on then just wire it so those 2 wires just make the relay turn on.