BCU - how to determine locked/unlocked state?

[goltho]

I need to be able to distinguish electronically between locked and unlocked states. More precisely, if the car is locked, I need to be able to ignore subsequent lock requests. Similarly, if the car is unlocked, I need to be able to ignore subsequent unlock requests.

I understand how the BCU receives its inputs in order to activate the various components included in locking and alarming (mainly via C0660). As far as I can see, the inputs are generally momentary earths.

Context
I've fitted a manual boot switch to the underside of the plinth and it works fine. When pressed, the switch closes and earths the GR wire between the interior boot switch C0221-2 and the BSU C0660-48. This then causes the BCU to send a timed 12V signal from C0660-2 to the boot actuator, opening the boot. In other words, it does exactly the same as the interior boot switch. Simples.

However, I now have to interrupt/keep the earth circuit open from the new switch to C0660-48 when the car is locked, to avoid the boot being opened/the alarm being activated/my stuff being nicked.

A mechanical latching relay would be fine if there was a guarantee that when the car's locked, no other signal could be sent to the BCU except an unlock one. (I could for example, trigger the relay from a door actuator if it was only sent power on the first Lock signal or the first Unlock signal.) This however is impossible (to guarantee) as I can press the lock button as many times as I want whilst the car is locked. So the relay would open/close/open/close to its heart's content regardless of which button was pressed.

So are there - BCU or anywhere - two outputs (going anywhere) dealing separately with lock and unlock? That would solve it easily. If not, what other methods are there to detect locked or unlocked state?

Sorry it's a long one.

Dougie.

[marinabrian]

Why not use pin 44 CO660 instead

Brian

[goltho]

Originally Posted by marinabrian

Why not use pin 44 CO660 instead

The fuel flap switch!! Why didn't you say so earlier??

So the motor appears to be wired in parallel with the superlock motors and activates on superlock/unsuperlock only (i.e. not CDL) ? That'll do for me.

Dougie.

[HarryM1BYT]

I'm not clear on what you are trying to actually do, but there is the red LED on the dash, which flashes every few seconds when the car is locked. Might that signal be of some use to you?

[goltho]

So there are two wires running to the fuel flap motor (red/white and green/black). On unlock, one squirts a 12v pulse and the other becomes the earth. On lock, the polarity is reversed to pull the actuator in the opposite direction.

This would be perfect except for the fact that re-unlocking whilst unlocked, squirts another 12v pulse (re-locking whist locked does nothing). This means a latch relay will still open/close/open/close if the unlock button is repeatedly pressed and will not be able to sync with the locked/unlocked status.

I'll look at using multiple relays as I'm sure there's a solution. Or maybe a microswitch on the fuel flap actuator arm. Just can't grasp it atm.

Dougie.

[sewerman]

This may be a stupid question but does the internal button work when the cars locked ? If it doesent you could extend the wires to it , if it does igorne this post

Scott

Sent from my SM-G950F using Tapatalk

[goltho]

Originally Posted by sewerman

This may be a stupid question but does the internal button work when the cars locked ? If it doesent you could extend the wires to it , if it does igorne this post

It's not stupid if you don't know! It does work, and triggers the alarm if pressed when the car is locked.

Dougie.

[Avulon]

Originally Posted by sewerman

This may be a stupid question but does the internal button work when the cars locked ? If it doesent you could extend the wires to it , if it does igorne this post

Scott

Sent from my SM-G950F using Tapatalk

But what do I know....

[goltho]

This should work. Small magnet on the end of the fuel flap actuator arm closing a magnetic proximity switch mounted no more than 8mm away when the fuel flap (and therefore the car) is unlocked. This charges a normally-open relay which closes the circuit between the boot switch and the BCU (C0660-48). When the new boot switch is pressed, it earths the BCU connection in exactly the same way as the interior switch does, but will only work when the car is unlocked.

.