"Foreign" Car Question

This actually concerns a friends VW Passat but I have asked the question on
a VW group for him and got no response. It seems to me that we have some
knowledgeable people on here and the problem (I think) could equally apply
to any make of car.

His Passat is only a few years old and has develpoed an electrical current
drain. It has been into the VW agents a couple of times and all they can
tell him is that his battery is fine, they can find absolutely nothing
wrong, but his current is draining away (this bit he knew). It is so bad
that on a couple of occasions he has had to call out roadside assistance to
jump start it and now carries one of those emergency power pack thingummys
in the boot.

I am wondering whether anyone on this group has experienced similar problems
and can shed any light on it.

 

Many years ago I had a similar problem with a Sierra. It took a while to
find out that the boot light was staying on when the hatch was closed!

A possible suggestion is disconnecting the positive connector from battery
terminal and then connecting an ammeter between the terminal and +ve
connector. There will be a current if the battery is draining.
Now remove and replace, one by one, all of the fuses to see if the current
suddenly falls. If it does you will have narrowed down the items to look at.

Worth a try?
Lenny

 

Unfortunately it is an estate so that problem would be obvious. However, I
have heard of some cars having a light under the bonnet so I will get him to
check that out. Thanks.

Keith W

 

Keith, You(or your mate) needs to take the other section of Lenny's
reply. Finding electrical problems on a modern car needs logical
elimination combined with understanding what you are doing.
No quick fixits in my experience.

Bob

 

It

Could

Be

Anything.

Best thing he can do is check out how much current is being drained using a
multimeter and try and track it down to individual circuits using a wiring
diagram. It may just be easiest to get an autospark to do it as the wiring
diagrams are often difficult to come by (the haynes ones are incomplete,
even in the good old days of relatively simple cars and relatively
comprehensive haynes manuals).

 

Check All the door switches. also the boot one , these bloody things
can play up and nobody thinks of these little things just sitting there
waiting to take the power out of the batt,(i bet it is one of them
playing up as it drfains the power over night,) good hunting..