VWs bad design...
tegwin - 26/8/09 at 11:16 AM
Ok, so the ABS is a critical safety system on a modern car (or atleast the MOT man says so)...
For months my ABS light has been comming on occasionally when I use the brakes heavily.
Last week it came on perminantly.....NOT GOOD!
Plugged it ino VAG-COM and the module is ok, but claims it cant conect to the pump...
So I figured the module might be faulty... went to VW... and they want £640+vat for a new unit 
In despare I did the locost thing and took the ABS control unit to bits... they are deffinately not designed to come appart!
It looks like this:
On closer inspection, the solder on the pump motor connector pin has totally melted and been sprayed all over the place! No continuity atall between
the pin and the driving transistors.
Apparently this is a common fault!!!
What sort of electical engineer does not take this into consideration!!
I have seen quite a few PCBs fail like this... but this is a £600 safety device....
Silly VW!
I resoldered the pins and hey-presto the fault seems to have been cured for now... fingers crossed it stays that way 
[Edited on 26/8/09 by tegwin]
Guinness - 26/8/09 at 11:19 AM
Nasty!
Will soldering it back up work? Or has the splatter knackered up other components / tracks?
Mike
omega0684 - 26/8/09 at 11:19 AM
take it into vw and show them
balidey - 26/8/09 at 11:21 AM
quote:
Originally posted by tegwin
this... but this is a £600 safety device....
[Edited on 26/8/09 by tegwin]
Nope, this is NOT a £600 item, its a £20 item that VW charge £600 for (as they can). There is a difference 
mikeb - 26/8/09 at 11:24 AM
has it defo melted or cracked? When I worked for TRW they were spending a lot of time and money FEA modelling circuit boards to try an reduce the
occurance of fatigue cracking on solder joints.
If it has melted that is rubbish design from the electronics engineer!
Mr Whippy - 26/8/09 at 11:25 AM
looks very easy to fix. Well done sorting it yourself
You could buy faulty ones off e-bay, fix them and sell them on at a massive profit to desperate VW owners 
I noticed VW’s part prices are appalling, they wanted £1000+vat for a classic Beetle carburettor cheeky buggers 
[Edited on 26/8/09 by Mr Whippy]
mikeb - 26/8/09 at 11:26 AM
Agree with the pricing, its a scandal the amount they charge for spares, no competition unlike mechanical components. So I guess they charge what they
want!
Richard Quinn - 26/8/09 at 11:28 AM
Has the solder melted through the current draw through that pin? Is that pin only live when the ABS is controlling the pump?
If the answer to both of the above is yes, drive slower or leave a bigger gap and give your ABS a rest!!
tegwin - 26/8/09 at 11:32 AM
I assume that the vibration+heat from the engine + heat from electrical surge has caused the solder to break down and then arc causing the spread of
solder.
I very rarely get the ABS to kick in, but on an 80,000 mile car, I guess the pump has been used a fair bit.
The clever(ish) thing is the little circuit between the pins that feeds back to the CPU to tell it if there is no pump connected... hence the error
code I was getting!
Do we really think VW would give a flying gnats arse about this? I could write them a letter and send them the photos... but is it going to get me
anything? (preferably a new controler)?
I know they did recall some ABS units for similar faults... but not on my car!
On a side note, the local scrapper had douzens of complete ABS units (£1200 from VW!) and wanted £80 each for them..
Sadly, they are all for the 1.4 The GTI I have is so rare I couldnt find one on the "heap"
[Edited on 26/8/09 by tegwin]
MikeRJ - 26/8/09 at 12:31 PM
Just looks like a badly made (dry) joint to me?
EDIT: if those pins are fairly long then the problem is likely due to thermal cycling that stressed and cracked the joints. You can see the PCB
designer has tried to mitigate this by milling cut-outs around the connections to make the PCB more flexible...obviously it's not really
sufficient.
It's hardly a massive safety concern since the brakes still operate correctly, it's jut that the ABS doesn't operate. Hopefully you
aren't the kind of driver that relies on ABS during day to day driving!
[Edited on 26/8/09 by MikeRJ]
tegwin - 26/8/09 at 12:37 PM
Haha.. I would rather have no ABS... the car brakes better without it!
It just needs the ABS for its MOT today!
And I couldnt remove the bulb... I did try :p
MikeRJ - 26/8/09 at 12:40 PM
quote:
Originally posted by tegwin
And I couldnt remove the bulb... I did try :p
hehe, a bit of insulation tape in front of the lamp would have been easier
The inspectors are supposed to test for correct bulb operation, though they don't always do this IME.
02GF74 - 26/8/09 at 12:57 PM
well done indeed for finding and fixing the fault.
what is on the other side of that pin?
I am not convinced that is due to over heating as there is no sign that I cna see of the pcb scorching - where is these melted solder bits?
It probably was badly assembled and came part after years of use is my guess but I don't deal with pcb board post-mortems.
If you told VW, they'll probabluy invalidate any guarante and inform you insurcane compay that you ahve been tampering.
keep stumm.
speedyxjs - 26/8/09 at 01:39 PM
If you want to make a bit of pocket money, advertise your VW ABS repair service on ebay.
The jag clocks fade and rather than pay £300+ for a new one, a guy on ebay repaired mine for £25 so it does happen
MikeRJ - 26/8/09 at 02:00 PM
quote:
Originally posted by speedyxjs
If you want to make a bit of pocket money, advertise your VW ABS repair service on ebay.
It would probably open you up to all sorts of liability issues in this nanny state 
tegwin - 26/8/09 at 02:00 PM
The melted solder was just in small balls loose inside the case... only a few tiny dust sized bits came out...
The other side of the pins is a socket that is part of the moulding.... two pole connector that goes to the ABS pump motor...
I wouldnt have thought there was much movement between the fixed pins and the board, but there is obviously enough.
Yes, I did consider that VW might not be happy...
How long do we think it will be before insurance companies start banning people from working on their own cars incase they damage something???!??
I dont trust a single mechanic.. having tried several garages I just cant get over how shite they are... no pride in their work!
r1_pete - 26/8/09 at 02:35 PM
Terrible design, any transistor which controls higher currents should be remote mounted on a heat sink, for this precise reason.
Its why you see them stuck out the back of trancievers and power amps on finned sinks!
David Jenkins - 26/8/09 at 03:05 PM
quote:
Originally posted by tegwin
On a side note, the local scrapper had douzens of complete ABS units (£1200 from VW!) and wanted £80 each for them..
Sadly, they are all for the 1.4 The GTI I have is so rare I couldnt find one on the "heap"
It's not a Mk 4 GTi is it?
My daughter had one - made me decide that I'd never buy a VW, ever. It was an absolute top-of-the-range Golf, which had the following faults:
1. A driver's door glass that fell into the door - plastic supports had broken. This fault still happens on cars based on that chassis, e.g.
Seats.
2. Glove compartment door that wouldn't open - due to a very cheap and nasty plastic pivot wearing out. A very common fault with these cars.
3. Water appearing in the rear passenger footwell - entirely due to poor design of drains and screenwasher pipes. Also a common problem.
4. Not on my daughter's car - but apparently the flywheel is riveted to the crank, and they've been known to come off...
I've now had 4 Toyotas in a row - not exciting admittedly, but I have NEVER, EVER had a significant fault with any of them. The biggest design
flaw I've found so far is the use of mild steel for the spindle of my rear wiper - eventually it corroded and started to squeak and slow down.
Took 30 minutes to fix.
l0rd - 26/8/09 at 03:40 PM
Should i be happy that i spotted the fault by looking for 15 seconds the first picture without even looking at the second one?
tegwin - 26/8/09 at 04:46 PM
quote:
Originally posted by l0rd
Should i be happy that i spotted the fault by looking for 15 seconds the first picture without even looking at the second one?
Its because you "know"! ... and yes... good skills!
Its the Mk5 Polo GTI...
I replace the rear brake switch and engine temp sender atleast every year...
The gearbox had to be rebuilt at 50,000 miles because it fell appart inside
The pedal box cracked where the clutch pedal is welded inplace (locost solution is obvious!)
But I cant sell it... its a fantastic car!