PSE blowing fuse

[DominoKing]

Just got a S Class, W220 5.0, 2002.
Hi there, a newbie, The central locking didn't work, what I did not realised that the car has been standing for some time and have had several issues with it. The airline to the boot lock had been damaged at the boot hinge and the previous owner had 'temporary repaired' it.
This is where I am. I have read several posts.
I have mended the airline with a tube repair kit. The central locking now works fine on all doors but the fuse blows when you try it on the boot. In any case, the boot has never been able to open electronically and only the mechanical key would work. I have checked the air going to the boot mech and there are no leaks. The PSE is working fine and makes all the right noises. The fuse also blows once I drive off.
I am getting frustrated now with the 'fuse blowing dead-end' and opening and closing doors etc with mechanical key.
Help please!!!
Is there something that I can checked with the boot lock mech etc before I go changing parts blindly.
Thanks in advance.

 

[mersum1es]

I had same issue, and 2nd hand PSE pump solved it. But like you have read if there is leak, it might blow fuse if even overrun time is not triggered. I could be useful to see if some actuator is asking vacuum (boot handle stuck or something). You will need coding anyway if you buy used part, unless donor car has same options than yours.

BTW same symptoms happened before when there was water in vacuum lines and it was frozen - once temp gone over 0C it worked again.

 

[DominoKing]

Thanks for that. I guess it might be the boot lock mechanisms but I don't have either part to swap and try out. I will try and do a 'work around' to identify exactly what it is trying to do when the fuse blows. I have stocked up on 20amp fuses as I reckon that it will take time. I will report my findings.