Hi all, has anyone added an additional lock button to the rear compartment of their Caddy? Would rather not have to climb into the drivers seat to lock the van from inside when I'm sleeping in the back.
From the wiring diagram it looks fairly simple - the drivers door switch is one wire, switched directly to ground for either lock or unlock, and via a resistor for the other.
Wondering if I've missed something as I don't seem to have seen this done before! Don't want to go tearing into the door looms if there's a better location to tap in.
You can use your key, just press it twice so the deadlocks don't engage (one press puts the deadlocks on and this means the van doors cannot be opened from inside no matter what you do, not good if the van battery dies while you are asleep)
But your idea seems sound enough, just worth noting this function is disabled when the van is locked with the key, the internal lock buttons no longer work when locked from the fob. Otherwise the deadlocks could be defeated by breaking a quarter light window and reaching in to press the button and hey presto, your local burglar is granted entry. However VW thought about this and the system deactivates those buttons once locked by key fob.
I suspect also that the alarm is not armed when simply locking the doors from inside using only that button.
2015 SWB Van, 1.6 CR TDI with Cruise Control, Heated Mirrors, Highline Clocks & MFD, VW Hands Free Bluetooth, Electric Windows, Reversing Cameras, DPF Monitor, Thatcham Cat 2.
STP wrote: ↑Wed Feb 18, 2026 6:46 am
You can use your key, just press it twice so the deadlocks don't engage (one press puts the deadlocks on and this means the van doors cannot be opened from inside no matter what you do, not good if the van battery dies while you are asleep)
Yeah fair enough on using the key! Just means you then have to disable the interior monitoring or trigger the alarm when you move about. Don't need the alarm armed as it would only be for when I'm sleeping inside.
Maybe I'll give it a crack and see. Had a look on the Transporter forums and they seem to have the same system and people reported success in grounding that wire via a resistor to lock, will just need to measure my door switch to find the correct resistor value.
jakemcc97 wrote: ↑Wed Feb 18, 2026 10:37 am
Yeah fair enough on using the key! Just means you then have to disable the interior monitoring or trigger the alarm when you move about. Don't need the alarm armed as it would only be for when I'm sleeping inside.
Maybe I'll give it a crack and see. Had a look on the Transporter forums and they seem to have the same system and people reported success in grounding that wire via a resistor to lock, will just need to measure my door switch to find the correct resistor value.
I have an alarm on mine but no interior sensors, do you have ultrasonics? If not, the alarm won't detect you moving about.
I've not seen interior monitoring on these vans but then I've never had a MK4, what is yours. Btw why not just lean over the seat and press the button then? Using the resistor on a switch will lock the door but not unlock it, the same wire grounded with no resistor is unlock, same wire for both functions. It's a 0.35mm wire so very low current.
2015 SWB Van, 1.6 CR TDI with Cruise Control, Heated Mirrors, Highline Clocks & MFD, VW Hands Free Bluetooth, Electric Windows, Reversing Cameras, DPF Monitor, Thatcham Cat 2.
STP wrote: ↑Wed Feb 18, 2026 9:41 pm
I have an alarm on mine but no interior sensors, do you have ultrasonics? If not, the alarm won't detect you moving about.
I've not seen interior monitoring on these vans but then I've never had a MK4, what is yours. Btw why not just lean over the seat and press the button then? Using the resistor on a switch will lock the door but not unlock it, the same wire grounded with no resistor is unlock, same wire for both functions. It's a 0.35mm wire so very low current.
Yeah got an ultrasonic sensor on the headliner facing back into the cargo area and an interior monitoring switch on the B pillar. It's a MK4, 2017 Highline.
Haha yeah I can just use the drivers door switch, will just be a pain once I put a curtain in (well, going for a zip down bulkhead), will be nice to have something I can tap by reaching out of bed!
