fuel and alarm buttons stopped working

cheechy said:
Sorry just realised the one that detects the door opening (microswitch number 5!) might be the cookie

How do I do a proper non destructive test given I cant see wire or connectors exposed?
Click to expand...
Can you not trace the wire / solder track to the connector and test the switch by using those connections?
Steve B
 
Thanks for patience - watched the you tube video on how to dismantle that microswitch.

having taken it to bits I think the switch or connection to the switch may be a little dodgy. When I try continuity its not reading 0 but 2 or 3? I'm assuming thats indicating an issue?

Indeed microswitch seems to read the same whether its on or off (touching the spring part) so looks like I'll need to find another switch and fit?
 
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In addition to confirming the operation of the switch as suggested by Steve, check the solder joints on the connector very carefully as they tend to fracture around the pin and this causes the intermittent connection that results in the problems you have seen.
Post a close up photo of the area if you want a second opinion.

Steve
 
Catnip64 said:
In addition to confirming the operation of the switch as suggested by Steve, check the solder joints on the connector very carefully as they tend to fracture around the pin and this causes the intermittent connection that results in the problems you have seen.
Post a close up photo of the area if you want a second opinion.

Steve
Click to expand...

See post #12

Long thread easily missed

Steve B
 
ok more pics.

As you are aware not an expert but is that a break on the track on the board or just an anomaly of the resin cover?

IMG_20171115_205722.jpgIMG_20171115_205846.jpg

Pic of switch also - looks fairly clean and clicks / returns ok.
 
So microswitch IS closing the circuit so I'm completely stumped tbh. The only thing I can see is continuity readings from the switch are always above 0 indicating maybe a sub optimal connection maybe?

Tempted to put it back in!

Sorry Catnip its a Nexus 5 so camera not brilliant.
 
ok last post for now!

Tried closer photo of solder joints - lots of camera induced white spots.

IMG_20171115_211609.jpg
 
cheechy said:
So microswitch IS closing the circuit so I'm completely stumped tbh. The only thing I can see is continuity readings from the switch are always above 0 indicating maybe a sub optimal connection maybe?

Tempted to put it back in!

Sorry Catnip its a Nexus 5 so camera not brilliant.
Click to expand...

Put it back in and without reassembling everything just try it and see what happens.

See if you can spot / test that the plunger is being depressed too.

It really might have been a dodgy connection that you have resolved by removing and replacing it.

Steve B
 
lol yup I was thinking the same thing if I'm honest Steve.

Thanks for sticking with me on this... :)
 
cheechy said:
lol yup I was thinking the same thing if I'm honest Steve.

Thanks for sticking with me on this... :)
Click to expand...

I enjoy trying to help.

These are great cars and when someone has an annoying problem it ruins the pleasure for them.

Fixing the issue does two things, the satisfaction of the achievement of fixing it great and then the pleasure when you get in your car and you can see that it is fixed means that you will probably be opening and closing the door extra times just enjoying seeing it working!!!

Fingers crossed that it will work when assembled, but do make sure that the plunger hasn't worn down.

Remember that you don't have to open and close the door to test it, just use a reasonably large screwdriver to act as the door "hook" in the B pillar
That way you MIGHT be able to see the operation better when it is back in situ.

Steve B
 
the red conformal coating means nothing, the joints are most likely cracked under the coating, the crack is actually between the solder blob and the pin which is running through the centre of the solder blob

Scrape off the red coating, and hit the joint with a hot soldering iron, ideally use a solder sucker to remove as much of the old lead free solder as possible, then re flow the joint with new, ideally leaded, solder

Cheers,
Paul
 
depronman said:
the red conformal coating means nothing, the joints are most likely cracked under the coating, the crack is actually between the solder blob and the pin which is running through the centre of the solder blob

Scrape off the red coating, and hit the joint with a hot soldering iron, ideally use a solder sucker to remove as much of the old lead free solder as possible, then re flow the joint with new, ideally leaded, solder

Cheers,
Paul
Click to expand...

Hi PAul,

would he need to do this even though the muti-meter is showing that all of his micro-switches are reading as they should.

But I guess that while it is all out and easy to do, it would be worth making sure? "Belt and braces" and all that?

Steve B
 
the problem with the multi meter check is that there is next to no current flowing, so you may well get the correct reading but then when the lock is working for real and there is a little more current flowing the joint shows it true colours i.e. fails

my own experience of the VAG locks is that the micro switch gets the blame for 99% of the faults, but it is nearly always the solder joints which have failed and seldom the micro switch is at fault, and when the micro switch is the cause a clean normally sorts it out. I bought 4 micro switches some years ago to fix some VAG locks, I have repaired dozens of VAG locks since then and still have the 4 micro switches unused in a bag, all have been failed joints or a clean as sorted out the problem

Cheers,
 
depronman said:
the problem with the multi meter check is that there is next to no current flowing, so you may well get the correct reading but then when the lock is working for real and there is a little more current flowing the joint shows it true colours i.e. fails

my own experience of the VAG locks is that the micro switch gets the blame for 99% of the faults, but it is nearly always the solder joints which have failed and seldom the micro switch is at fault, and when the micro switch is the cause a clean normally sorts it out. I bought 4 micro switches some years ago to fix some VAG locks, I have repaired dozens of VAG locks since then and still have the 4 micro switches unused in a bag, all have been failed joints or a clean as sorted out the problem

Cheers,
Click to expand...

Thanks Paul given I managed to "acquire" a small amount of 0.3mm tin lead solder then I guess I'll pluck up the courage to use.

For sure I think the switch or more likely solder on the board connectors cross well be dodgy here so I take the point on fully that even if it were to work now they child must as easily fail again next week!

Any tips on removing the resin without damaging anything by the way?
 
I'm guessing this is why I dont go anywhere near circuit boards...

No skills and poor tools.

I'm assuming this is scrap now yes? :)

IMG_20171116_214725.jpg
 
err well it does look like you have broken two of the circuit board tracks, if so then yes it is now scrap

I said use a scalpel not an hammer and chisel :)

Cheers,
 
depronman said:
err well it does look like you have broken two of the circuit board tracks, if so then yes it is now scrap

I said use a scalpel not an hammer and chisel :)

Cheers,
Click to expand...

Believe it or not that was the solder sucking thing. Its fairly vicious truth be told and sucked the track right off - mind you i must have been applying heat to the wrong place.

I might have to find a local friend whom isn't so ham fisted :)
 
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