Solenoids, how do they work?

[b2tf]

Hi all

after a bit of info on how solenoids work, specifically one that opens the fuel filler door on sedans. I have one here and Ive just about got it figured out to work on the ute, I just need a bit of info on how they are powered etc. It has 2 connectors (just prongs) so I am assuming its just a matter of getting power to it, then connecting it up to the loom in the dash so the button works? Is this correct? I have the button on the dash in there now and it does have a loom to plug into, but I havent traced it yet to see how far it goes.

[tufLTD]

Solenoids are the electro-magnetic device usually used to push or pull a plunger. Power is applied to create a magnetic field that moves a metal plunger in or out. All they need to operate is a positive & negative wire. Positive current is supplied through a simple on-off switch and the circuit is completed with an earth wire.

[b2tf]

Sounds easy enough. I think the hardest part will be wiring the switch in the dash so it works correctly.

[tufLTD]

Originally Posted by b2tf

Sounds easy enough. I think the hardest part will be wiring the switch in the dash so it works correctly.

It would be best to use a positive power supply that is always on (direct battery current), regardless of igniton on or off. That way you can open your filler cap without having to use your key or turn ignition on. You should be able to locate an "always on" power supply from the fusebox with a simple circuit tester.

[zetec]

I wouldn't advise that... battery wouldn't last too long. I think the car turns them on when the doors are unlocked.

[tufLTD]

Originally Posted by zetec

I wouldn't advise that... battery wouldn't last too long. I think the car turns them on when the doors are unlocked.

Why wouldn't the battery last long???
There is no current draw until you operate the switch.

[zetec]

Yeah good point. It's late on a Friday. Brain's off!

[Tech Trainer]

However I would advise a fuse in the circuit, just in case the power wire rubs through and develops a short circuit.

[teabags2]

Solenoids are built to provide high levels of mechanical force for a short time. That is they will oveheat and burn out if you keep them powered up for more than a quick click to release the latch. The switch needs to be monentary so you don't accidentaly leave it turned on and burn the solenoid out.

Bob

[chief]

Originally Posted by teabags2

Solenoids are built to provide high levels of mechanical force for a short time. That is they will oveheat and burn out if you keep them powered up for more than a quick click to release the latch. The switch needs to be monentary so you don't accidentaly leave it turned on and burn the solenoid out.

Bob

A relay will solve this problem.

[b2tf]

Ok next question, on a ute, whereabouts does the main loom run to its furthest point on the back of the car? I.e, where does it stop?

[bodes-sh]

i would probably say fuel pump, that is behind the cab anyway and almost to where you will want the wiring for a fuel door release...that and the tail lights

[tufLTD]

I would guess that the rear-most point which provides constant battery supply would be to door courtesy light switches. It would be easy to branch into this wire & run it to the fuel cap solenoid.

[b2tf]

Originally Posted by tufLTD

I would guess that the rear-most point which provides constant battery supply would be to door courtesy light switches. It would be easy to branch into this wire & run it to the fuel cap solenoid.

The main loom from what I can see already has wires to power the solenoid. It has a plug thats in the dash where the buttons attach, I just need to follow the loom to find these wires.