MegaSack DRAW - This year's winner is user - rgwb
We will be in touch
Basic question,
Say the ignition is on, are the wires 'live' ie have current all the time, or only when an 'on' switch is activated. Trying to determine faulty wires on a car's central locking. Have access to the wires and a voltmeter.
think i'll just run second temporary wires across it to see if this resolves the problem.
Use your voltmeter and find out
Obviously the wire will be live to the switch and then when switched on it will be live to the appliance. your central locking will always be live irrspective of ignition or else you would not be able to get in it. Check manual some are vacum operated and dont actually require power iirc.
would gues at a common live to a power unit and another signal to move it open and another for close.
When you switch the key from OFF to ACC to IGN, you are applying Voltage (not current) to various circuits. Some circuits are always live (voltage applied) - like the hazard lights, interior lights, sidelights, headlights etc. Some are made live when the key is in ACC - sometimes radio, blower, horn, indicators, etc. Others are only mad live when the key is at IGN - starter circuit, fuel injection/engine management, ignition, sometimes radio, etc.
The voltage which has been applied to a given circuit will be present on the input side of whatever switch controls it. Once the switch is closed (switched on), then current will flow in the circuit (assuming no faults etc).
BTW, central locking is live all the time, regardless of the key in the ignition.
that's great thanks all. 😀
They'll only have current when something connected to them is working. Otherwise, there'll be a VOLTAGE before the switch and not after it...
cheers. Out of 4 wires and an earth I have found that only two oin each side have voltage through them.
What car is it?
If you can get a haynes manual then this may well help you out a lot as they have circuit diagrams for a lot of the systems. Good places to try are your local library and even charity bookshops!
Depending on the age/type of car, vehicle electrics can be very complicated. Some wires will be for the CAN bus (although not likely for central locking), and if you disturb these wires it has the potential to cause more widespread electrical faults.
The main thing is to be as sure as possible what the wires you are playing with do before you start hacking in/cutting away/whatever
Hope this helps 🙂