decided to be fancy and plot a little path of wire for a relay and buzzer to buzz when the lights were on and the door open, a reminder buzzer.
so a wire off the main lights and an earth shared off the door trigger for an earth, seemed to work all fine until I realised that now the internal lights don't turn off at all. period.
seems once the door closes an the buzzer is off it permits an earth back to the lights. and when the door is closed and the head lights go on the interior lights go off.
so where is my floating earth or my phantom power coming from.?
if I remove the earth trigger at the door then the interiors work normally again.
do I need to diode the (+) power from the lights or add a separate earth trigger?

 

Disclosure:

I'm only two sips into my first cup of coffee, have only a Series III wiring diagram, I've had a rough week, and the sun is in my eyes.....

-Where, physically, did you tap into the 'door trigger' wiring? The Series IIIs have one or two diodes hidden in the circuit. If you get on the wrong side of a diode all manner of anomaly could occur. I've done the same buzzer mod and tapped into the circuit as close as possible to the door switch.

-The circuit has purple and purple/white wires (again, from Series III diagrams). You want purple/white

-The buzzer itself might present a problem depending on its internal circuit? I dunno.

-Any other wiring mods or problems? On a Series III, for example, if the power antenna fuse blows, the interior lights stay on due to some strange back-feed that I never understood.


Hopefully others ....more alert at the moment...will come along with other ideas

Cheers
DD

 

drivers 'door trigger' plugged the bullet from the trigger into a bullet splitter sheath and popped an additional bullet connector in there which made its way to the light alarm. when i removed this additional connector the interior lights resume normal function, so the issue is coming from the alarm sharing the common earth with the trigger.
as the problem stops when the lights come on (i.e when power is being feed from lights to relay for buzzer) I assume the inactive relay/buzzer is forming some type of floating earth.

 

Hello Aden . . . greetings from across the ditch and I believe I can assist while assuming you understand "ground switching" rather than the older "power switching" used before the emergence of digital electronics. However, for all its benefits, it comes with a caveat . . . your opening confirms that you've found it and later, you nearly propose a solution.

You can combine multiple parallel grounding switches for a common controlled device - eg your Jag's multiple door switches. Also, you can combine parallel controlled devices, eg multiple lights, which are all controlled by the door switch(es). Likewise, for your main lights, you could add other ground seeking control switches, or add a parallel controlled device, eg buzzer, but this would sound while ever main lights were on, irrespective of whether door is open or shut.

Your problem arose as soon as you breached the caveat - combining two or more conditions through now cross connected main light and interior light ground seeking circuits is verbotten without suitable circuit isolation. Diodes may do the trick, but without your wiring diagram in front of me I'm hesitant to suggest that approach. A far simpler solution presents . . . although the telling makes it sound far more complicated than it is.

Firstly, remove wiring mod to your main lights. Ignore door switch tap but disconnect buzzer. Secondly, please confirm that your park light circuit must be on for your main or dip beams to be on . . . and thirdly, it is CRITICAL to check that all your park light switching is on the "ground seeking" side. Simple multimeter check, with all lights off, is that you should see B+ (nom 12V) on BOTH sides of parking light when measured to body earth. If not, stop and come back.

Again, next is CRITICAL. Purchase a 12V SPST relay rated for buzzer current, but it must NOT share any of its terminals between the 2 switch contacts and 2 coil contacts and NEITHER COIL CONTACT CAN BE CASE GROUNDED. They do exist (try Jaycar and forget auto horn relay). I cannot over-emphasize this, because we now strap each side of relay coil across your chosen park light - perhaps under dash if using console wiring. Complete this phase by confirming relay clicks from off to on in accordance with main light switch moving from OFF to any other position. Re-check that there is no connection to either power or ground, in either state, from either switched contact.

OK . . . now we supply fused B+ power to one of our relay contacts, thence from opposite relay contact to buzzer; finally from buzzer to ground seeking bullet connection at door switch. Only thing to emphasize here is to tap into a suitable fuse - 5A should be ample - and ensure that it is permanently B+ fed ie not via IGN or some other switched wiring that will lead you straight back into problems.

Finally Aden, and I know you will, keep us posted on progress and outcome.
Cheers and best wishes,

Ken

 

Re-reading my previous post begs one final explanation which I am sure someone will ask for . . .

• if condition 1 (main light switch has moved from OFF), then the relay is energized, contacts make, and the buzzer will sound if and only if, and even then, only for as long as our condition 2 is met;
• if condition 2 is met (any door, not just that connected to, is opened), then provided condition 1 is NOT met (main lights are OFF), the buzzer will NOT sound;
• if condition 2 is met (any door, not just that connected to, is opened), then provided condition 1 is also met (main lights still ON), the buzzer will sound . . . but only until we either turn main light switch to OFF . . . or, we shut the door. In either case, buzzer will stop.

I believe the latter important to ensure you can still leave car with park lights ON, lock car, dash into pub to fill up on supplies, without having a buzzer upset the natives. Of course, when you stagger back with your supplies, the moment you open any door, the buzzer will recommence sounding . . . then to stop again when you shut door.

To preempt homework for tonight (LOL), I believe this is an example of wiring a Boolean Logic AND circuit whereby only if BOTH conditions are met do we get a change of state (1), and whenever EITHER or BOTH conditions are NOT met we get no change of state (0) . . . not quite the same thing.

Cheers,

Ken

 

FWIW.....

On Series IIIs I've done the headlight buzzer thing using a buzzer like this:

https://www.radioshack.com/products/...FYmRfgod498PwA


Red wire from buzzer goes to the red/slate wire (parking lamp) at the headlight switch

Black wire from buzzer goes to purple/white wire at the driver's door switch

That's it. Worked fine.

Next time, though, I change things 'round so that the buzzer will not activate if the key is 'on'.

Cheers
DD

 

It dawns on me that, on the Series III, the driver's door switch is isolated from the others via a blocking diode. Not sure about Series II cars

Cheers
DD

 

A diode on the line from the light's power did the trick. Appeared to be creating a floating earth when it was turned off, but now all seems good. Thanks for all of the information above, I might well look at refining the switch shortly too.