Technical Open door warning light

[Snails]

Hello everyone,
Recently I've come across a new quirky problem with my GP.
On the very frosty evening of Dec 30th I was picking someone at the airport. After putting the luggage in the boot I've noticed that the "Open Door" warning light would not go off.
My first thought was the boot sensor, found out (thank you FiatForum) that it's integrated in the latch. Ordered one, installed it (thank you again FiatForum tutorials) aaaand the light was still on.
The dome light comes on and goes off when the doors are opened/closed.
The boot light comes on/goes off when the boot is opened/closed.
This is the point where I asked for help from a friend who is an auto electrician, he checked the connections and my original latch with a multimeter, everything is fine. He requested the diagram for the entire central locking system and for the instrument panel tonight from a technical center that operates for car shops, apparently he doesn't trust the schematics in AutoData.
Hopefully we'll find what's wrong and fix it, I'll update this thread as soon as we get somewhere.

 

[DGPunto]

Have you checked the wiring between the hatch and the car body in the rubber concertina hose at the top of the hatch? That can get bad - thinking you might just have a short

 

[Cat2]

I hope you find a solution as I'm having the same problem, amongst others [emoji24]. Do your lights flash like xmas lights when locking the car? Mine locks but flashes like that cos there's a door open but must be the boot as I can hear the central locking and the doors are locked [emoji53]

 

[Snails]

Have you checked the wiring between the hatch and the car body in the rubber concertina hose at the top of the hatch? That can get bad - thinking you might just have a short

Yes, I have, the boot light would have stayed on permanently if the problem was located there. The wires are pristine, I usually open the boot twice a week, once to put the shopping in and once to take it out and bring it into the house.

I hope you find a solution as I'm having the same problem, amongst others [emoji24]. Do your lights flash like xmas lights when locking the car? Mine locks but flashes like that cos there's a door open but must be the boot as I can hear the central locking and the doors are locked [emoji53]

I hope so too, my OCD's tingling because of that open door light in the dash. Yes, the signals flash like strobes in the club, my friend who is helping me with this thinks the problem might be related to the central locking module on the comfort ECU. I'll swing by the shop Monday afternoon after work so we can check the wires. Hopefully he received the diagram yesterday.
I'm 99% sure it's not the boot latch or wiring, we both checked that possibility.

 

[Snails]

Paid a visit to my friend at the shop this afternoon, we looked over the central locking diagram.
It seems door the sensors (S23L and S33) send their signal directly into the comfort ECU (CHASSIS ECU A20 on the diagram) which opens the circuit with the instrument cluster P21i.
The comfort ECU is also the comm gateway between the door sensors and the interior lights (Int) which work. By analogy we can safely say the connection between the door sensors and the comfort ECU works fine. What is left is the connection between the comfort ECU and the P21i which is most likely the culprit. These 2 connections have a 20A and 5A fuses on them, I saw that in AutoData when I tried changing the latches. Not knowing which ones they are I checked all 20A and 5A fuses in the cabin at the time, they were fine... unfortunately not such an easy fix.

I'm scheduled to bring my car in next Monday, I'll let you guys know how it went.

Also I've attached the diagram for the 3 door GP central locking if anyone should need it.

 

[Andy Monty]

check door loom cable plugs for corrosion

 

[Andy Monty]

OH and from Memory the boot switch has 2 switches in one... One is N/C one is N/O one does the boot light and the other the open door warning...

 

[Snails]

OH and from Memory the boot switch has 2 switches in one...

Where are these located please?

 

[Snails]

Found the culprit, it's the instrument panel itself. No way to fix it, must be replaced.
Apparently that's the reason why the seatbelt light came on 5 years ago and never went off... I thought it's a dodgy connection in the seatbelt socket itself but I deactivated the buzzer then and it didn't bother me much.