VCDS Interior Alarm Sensor Error Code, went to swap and theres no cable !?!

[john_o]

Interior sensor error after a VCDS scan

03156 - Sensor for Anti-Theft System (G578)
            004 - No Signal/Communication

I bought a 2nd hand replacement interior sensor from ebay (on the assumption it was broken), but I went to replace it today and theres no cable attached to the existing sensor (!) WTF

Is it bluetooth or some form of wireless or has the cable just gone awol?

I did look around the roof area but nothing to see.
Which side does it route from

Edition  35 2012 with sunroof

thanks
John

[john_o]

Ok, so found this diagram on the net (https://workshop-manuals.com/volkswagen/golf-mk6/vehicle_electrics/electrical_system/lights_lamps_switches_inside_anti-theft_system/lights_and_switches_in_roof_trim/front_interior_lightw1_(vehicles_with_anti-theft_alarm)/removing_and_installing_front_interior_lightw1_(vehicles_with_anti-theft_alarm)/) and it looks like its a cable (as expected), which means its AWOL, damn

[Shoduchi]

Maybe someone removed the cable or started the retrofit of the interior alarm and never got that completely done...

[john_o]

thanks for the reply, isnt the ultrasonic alarm standard fit on a Ed35?

Tonight Im going to go digging for the cable

[Shoduchi]

I have no idea about the standard equipment. Mine has it, but it’s an Ed. 30. 

[john_o]

Im prettty sure the alarm with ultrasonic sensors is standard fit. 

Had it back apart tonight and finally found the cable tucked up round body brackets (!)
texted Previous owner and he was not aware of any issues..

Not sure whats gone on but maybe the first owner had it removed to avoid alarm draining the battery ? (car is low miles for age, so was stored for extended periods)

replaced sensor (heck why not, Ive bought the ebay part now)
no coding required
Used VCDS and cleared codes
Alarm led now flashes properly (not 10 seconds solid to indicate fault)

car been locked for 2 hrs now and still appears ok.

lets see what happens over the coming days, looks encouraging so far.

Next time you lock your car , check out the led flashing pattern, if it stays solid for 10-30secs you have some kind of alarm fault..

[Shoduchi]

Nice! Yeap, these cars spend a fair bit of power even when locked and the battery might suffer if left for too long stopped.