If I wire internal lights to 2nd battery I lose IR locking

[kenbw2]

I've got a leisure battery installed so as not to drain the starting battery when using internal electrics such as lights, stereo and cigarette lighters. I have a voltage switched relay to charge it, and use spade connectors into the outlet on the fuse box to wire up the electrics off the leisure battery. Those are solved problems and I'm not looking for advice on those.

The manual states:

- Fuse F15, 20A, "Central Locking, Timer, Window and opening roof relays
- Fuse F30, 15A, "PLIP, Hazard Warning Switch, Lights on Audible Warning Buzzer, Glove box lighting, Telephone, Spot Lamp"

I have a confusing situation though.

- Fuse F15 is for the centrally switched internal lights, not ignition switched
- Fuse F30 is for the individually switched internal lights, ignition switched
- Fuse F30 is also marked as "PLIP", which I gather is the remote locking

I'd like to power F30 from the leisure battery. If I do though, I seem to lose remote locking. If F30 is disconnected though, I get it back, which makes no sense.

Here's a handy diagram that explains it all:



What's going on?

[Peter.N.]

Very neat circuit diagram! I can only suggest you are putting a permanent supply where there should be a switched one, have you checked to see if there is any power on F30 with the ignition off?

Peter

[kenbw2]

I'd assume though that a circuit that's ignition switched is the same with a permanent feed, except that it's on when it'd normally be off. I don't see how that'd stop it working

[Peter.N.]

I also would have thought so but having been a TV engineer for 50 years I have learn't that logic doesn't always apply. Is there any part of the circuits that is connected to a permanent supply, is there possible a diode in the circuit preventing the flow of current in one direction. You really need a full diagram of the circuits and an understanding of how they work - I don't have either I'm afraid.

Peter

[ekjdm14]

maybe the feed fro F30 is an ignition supply to the alarm/locking to stop the alarm being accidentally armed/set off whilst the vehicle is driving, the IR must have a separate non-switched supply for it's actual functioning, this F30 supply is simply an interlock?

Don't know if I've described what's in my head very well, but sure someone else could word it better if I've lost you lol

[kenbw2]

According to this thread, there's a relay in there for "8) Impact central locking opening relay". At a guess, I'd say F30 is ignition switched, and powering that relay inhibits the circuit.

Could I theoretically bypass the central locking relay by removing it and/or bridging it with a wire?

[dnsey]

No doubt it's the logic that prevents you from locking the doors if one of them is open (and the interior light is therefore on). You're effecively 'backfeeding' the system by connecting your battery to the lights.
I think you'll need to completely isolate the lights from the door switches in order to fit your battery.

[kenbw2]

Ah, that explains why the locking and the lights are linked on the same fuse. To be honest I don't like the don't-lock-if-the-door-is-open feature (my 106 didn't have it) so I'd be happy to see that go.

What do you mean by backfeeding the system?

[dnsey]

Normally, the locking system will sense when the doors are open by detecting the voltage from the door switches (which also operates the interior lights). By connecting your battery, you are introducing an equivalent voltage into the circuit, so the system 'thinks' the doors are open.
When you remove the fuse, of course, the link to the locking system is broken, so it works normally - your experiment shows that there's another feed which actually operates the locks, and F30 is common only to the door-sensing part of the circuit.

[dnsey]

To be clear, the above is just guesswork, but with many years involved in electronics, it's a fairly educated guess
BTW, what's the vehicle? Although the principle holds, if it has a BSI, the reality will probably be more complex.

[kenbw2]

I can see what you're saying, even if it's not the door switches there could be a whole array of things involved. In this case I don't think the door switches are the problem, as when the doors are open the system locks and then unlocks, as opposed to just not working. Grr, why do they not just give me a wire =/ One option available to me is to use the centrally switched ones. They're not preferable as they're for some reason not as bright, but also time out after 10 minutes or so - maybe I could bypass the relay for that?

It's a '96 Synergie btw, the one with the 1.9TD.

[Peter.N.]

Strip out the multiplex and hard wire it.

Peter

[kenbw2]

Sounds good. What does that mean?

[wheeler]

There's no BSI or multiplexing on a Synergie. It may however have a CPH unit that controls the central locking & interior lighting, cant remember the changeover year. I think the change over was when the remote locking moved from IR plip to RF plip.
I think the problem here is that on almost all cars that I can think of with remote central locking the remote doesn't work when the ignition is switched on or the engine is running, I would assume that the circuit that does the ignition operated interior lights also provides the locking system with its ignition feed to stop the plip operating when ignition is on, by giving this circuit a permanent live it thinks you have switched the ignition on therefore disables the plip from operating hence the reason the central locking works but the plip doesent. Sound feasible ? if its not CPH operated you need to locate the central locking control unit & isolate the now permanent live (but previously ignition) feed.

[kenbw2]

Yea that sounds like a workable theory. Could the answer to that though lie in one of those relays in my glove box? Maybe if I bridge, or disconnect one of those it'll remove that voltage detection part