Do these tiny rust can trigger rear window alarm?

Sylvester

Member
Hi all, my alarm has been going of from time to time, the scan shows these:
20230319_154738.jpg


The 3/3 fault code is the "drivers door doesn't disengage", I know it's due the microswitch is acting up, not sure that's related to the alarm isssue, as the fob opens/locks all doors, the drivers door only doesn't open 1st time when locked from inside, it does second time though.

I've read up about it and took the tailgate trim off to check the sensors. It took a lot of effort to take it off, that things was fitted very well.
20230319_154252.jpg

Underneath the trim looks like brand new, apart from those screws turned literally rust.
Can those tiny amount of rust on connections, see pictures, cause the alarm to go off? There's no open-circuit fault code, so I don't think the wires are damaged behind the pillars fortunately. Cheers
 
Those 2 you are mentioning are not alarm but for the radio aerial or perhaps the heated rear window ( can not remember exactly which. The glass break sensor connector is visible in your upper picture in the top left corner. It is the press stud that ironically looks like and aerial connector...

Alarm triggered by luggage compartment switch is the tail gate not fully closed or the light coming on in the boot. Check all connections and clean the corrosion off think I can see marks around the wiring plig on the lock. Check the boot light switches off or even remove the bulb to see if the alarm is still triggered.
 
The glass breakage sensor uses part of the rear screen element to act as a continuos loop. When the loop is broken by the glass breaking or being disconnected the continuity is gone and the alarm is triggered.
 
The glass break sensor connector is visible in your upper picture in the top left corner. It is the press stud that ironically looks like and aerial connector...
I was wondering what that was. All 3 connections look a tiny bit rusty, how can I clean them up without damaging them? Does that sensor can clip of the glass or should be a permanent fix? Perhaps if I disconnect the battery I'd clean up around it
I think the back up system I read about, doesn't last anymore, I used disconnected the battery when battery had to changed and alarm turned off right away. Thanks
 
You need to be careful when cleaning not to cause other damage. The 2 square connectors are I believe soldered onto the glass and never meant to be removed. The glass break sensor is a stud fastener that can be gently and carefully edged away from the glass. In all cases use electrical contact cleaner, but IPA or meths can be used. Take great care not to spill any on paintwork or plastics.

If the screen side of the glass break sensor is badly corroded or even falls apart then there is not much you can do. Small damaged areas can be reclaimed using the special paint they sell to repair rear screen elements.

Not sure if the glass break sensor expects to find a certain resistance from the screen elements or it passes a small current through them so it may not be as simple as just joining the connects terminals together. Think of the glass break sensor operating in a similar manner to the brake wear sensor.
 
You need to be careful when cleaning not to cause other damage. The 2 square connectors are I believe soldered onto the glass and never meant to be removed. The glass break sensor is a stud fastener that can be gently and carefully edged away from the glass. In all cases use electrical contact cleaner, but IPA or meths can be used. Take great care not to spill any on paintwork or plastics.

If the screen side of the glass break sensor is badly corroded or even falls apart then there is not much you can do. Small damaged areas can be reclaimed using the special paint they sell to repair rear screen elements.

Not sure if the glass break sensor expects to find a certain resistance from the screen elements or it passes a small current through them so it may not be as simple as just joining the connects terminals together. Think of the glass break sensor operating in a similar manner to the brake wear sensor.
I'll try to clean it up and see if that work. Just out of curiosity, if that sensor falls of, would it trigger the alarm?
 
Sensor falling off would be seen the same way as the glass breaking. The circuit would be incomplete.
Finally it's stopped raining for now, so I'm gonna spray the rusty connectors with contact cleaner spary.
I'm just not sure, if I'd remove the battery lead first, or it can be done while electricity is flowing in them? Thanks
 
Use a cotton bud to get into the connectors just make sure no fibres left behind.

Always good idea to edge on side of caution so no harm at all disconnecting the battery. Just make sure all doors are unlocked and at least one front window down should you run into other issues.
 
Use a cotton bud to get into the connectors just make sure no fibres left behind.

Always good idea to edge on side of caution so no harm at all disconnecting the battery. Just make sure all doors are unlocked and at least one front window down should you run into other issues.
Yes I'll do that to be safe, I don't want to lock myself out. Thanks!
 
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