Central lock causes battery drain ???

[Marco77]

Hi guys, I have a problem with a "parasitic battery drain" in my 1999 V70.
I am just a self taught "Youtube mechanic" and this problem bugs me

So I did the obvious checks (battery is fine, alternator is fine) .. Next I used my multimeter to measure for Amp draw from the fuses - and located the Amp draw as comming from Fuse number 6 (Central Lock). I pulled the fuse to the central locks and the Amp draw instantly dropped...

So I have located the problem - but I need any advice on how to try to solve it...

I dont understand it, because the central locks are all working (All the doors lock and unlock from the driver side door). But the Ampere draw is happening no matter if the doors are locked or unlocked

Also I should mention that I dont have any alarm system or any remote control connected to the central lock. (the central locks are activated and deactivated only by manually inserting the key in the driver side door).

ANY suggestions are mostly appreciated. Thank you so much guys in advance for your help

Marco

[abscate]

Hei and Welcome to MVS!!

I am going to send a link, but promise me you won't hurt yourself after you read it.

(I have this same problem on my S70 and can probably publish a large book on this - not solved yet)

The problem is probably a board level component in the 2/76 lock controller - the other symptom that might occur is your interior lights won't turn off.on correctly

The first page of the thread below has a diagram of the system which is incredibly complicated.

viewtopic.php?f=1&t=88623&hilit=1999+S70NA

[Marco77]

Thanks abscate ... I will check it , but allready from your description it sounds like that might be IT ...(because I am having problems with the interior light not turning off as well ...

But please let me know if you ever find a solution, and I will do the same as well ofcourse

[Marco77]

Okay so obviously I am not even gonna go into trying to "fix" this lock controller module 2/76 , but my next question then is if it would be possible to simply replace this module (just find these controller modules from a scrap Volvo ?)

[abscate]

I tried replacing mine with a junkyard one from a V70 via eBay and had some compatibility issues, despite it being exactly the same part number.

Definitely try this.

[Marco77]

Okay .. Thanks again . I think I will give it a try . If it doesnt work I will just have to switch it back and somehow learn to live with it ... (Allthough its a real pain) - especially when I dont drive the car every day and the battery doesnt get charged so often.. I will have to just pull the fuse in between driving then

[abscate]

Short version of that long thread.

If the car sits overnight, everything works fine. The interior lights all work per the manual

The instant the ignition is energized , the lights come on and stay in, and only turn off with the overhead switch turned to the OFF position.

Mine occasionally reverts to normal operation for a few days but then the problem comes back.

Fun fun fun

[Marco77]

Oh Yeah.... That sure sounds familar
Mine also functions normally from time to time during a few days , and then gets messed up.

I cant believe just how complicated this system is.. even though I try to wrap my mind around it , its just way beyond my brain capacity lol

[abscate]

I’ve got about three more weeks of shutdown, so I would love to “slay this dragon”

It has been left to live too long



I will start a new thread on this

“

[Marco77]

Absolutely . Thank you abscate for helping as much as you are able . It is much appreciated .
I will keep an eye out for new posts on this and anything we can do to get closer to fixing this problem ...