ABS pumps Solution with pics!

[tegwin]

This is not good!

My ABS has been playing up for ages, the light has been comming on more and more often...

I have unplugged the ABS control unit and pump and then reconnected them and this was the last straw, the ABS light now stays on perminantly...

The MOT is due tomorow... doesnt look like its going to pass that!!!!

I suspect that the control module has failed, VAG-COM tells me that the pump has gone, but I suspect its more likley to be the control module...

VW wand £600+vat for the control unit and £600+vat for the pump unit..... I told them to go bugger themselves!


So I am a bit screwed..

The local scrappy has a couple from a 1.4 polo... Are they the same? I guess I could get a secondhand £80 complete unit and try it out....


I am not 100% sure if its the control unit, or it could be the wiring loom or something else....



But having read threads on here about it, I do suspect the control unit...

So, can I use a 1.4 unit?

[watkins.alex]

hi mate, try the fellowing out and see if this does anything,
the four fuse's on the top of the battery take them out and clean them off with sand paper and but them back in, and also there is a plug under the rear seats disconect it and the re connect it and see what happens it got rid of my abs light on my dash

alex

[alexperkins]

the abs pump on the GTI is slightly different from what I remember due to the EDL system

Also check the connections on the front sensors and the cables for any signs of damage as this can also have an effect.

Itll need vagcom to clear the abs fault, but as alex said, try cleaning those fuses, as I have seen it work in the past!

[tegwin]

Nope... Your all wrong!

The fact that I could not manually fire the pump, but that everything else on the control module was working gage me a thought....

I was about to go hang myslelf in despair..... but instead, I took out the ABS control unit... and after fighting with it for an hour I managed to get the lid off...

I kinda figured, its buggered so might as well tear it appart and smash it up... its only £600 for a new module..


And this is what it looks like:


In the top left corner is the connector for the ABS pump motor. It is driven by two transistors on two seperate circuits.

Between the two connectors for the pump motor is a simple sensor circuit, if there is no motor plugged in (IE open circuit) this circuit feeds back into the EEPROM IC in the centre of the board and presumably tells the system to shut down and give a fault code...


Amazingly, on closer inspection this is what I find!


The pulse loading on the soldered joint for the motor connector was not up to the job, it has melted and failed!!! There is NO connection to the pin!

10 mins with a soldering iron and the fault code has GONE!!!



If anyone else tries this, MAKE SURE you dont insert anything into the case when you are trying to lever the lid off, you WILL destroy the circuit board! And make sure you seal it back up properly afterwards with silicone so it doesnt get wet!

[tsaks]

Dear tegwin,
I had the same issue. Went to the garage(in Greece where I reside) and they hooked the car to the diagnostic machine. The response of the mechanic was that I needed to change the abs system(what he said) which would set me back approx. €700 +labour. I decided that it was not worth it.
After having issues with the abs light being on for the past 4 years, especially during the summer months(in my head it was heat=no abs) I stumbled upon your post.
I have tried what you said and now am a very happy person! I have to admit that after saving me so much money, or rather enabling the ABS on my car, I owe you a beer.
Mind you, in my case, due to the LHD car, it was much trickier than the RHD cars as the main brake system is approximately 1 cm away from a couple of bolts to the abs controller cover.
I opted to do it on the spot by the way, rather than removing the whole thing and having to bleed the brakes. I will bleed the brakes at some point, but not yet.
Anyway, HUGE thanks to you.
Best regards.

[tegwin]

No worries. Im glad it helped

Its worth noting that you dont have to remove the entire ABS unit, you can undo the four small headed bolts on the top of the unit and lift off the controler, leaving the actual pump block inplace.

[neilGTI]

I am on my third one of these now (modules) due to failure.

Thanks for the pics, i think i will be fixing the 2 broken ones i have myself now, rather than replacing them with ebay finds.

Just how hard was it to get the lid off, are there any clips, etc or just prize it off ?

[tegwin]

Getting the lid of is a PITA! if you get it wrong, you could end up totalling the circuit board inside...There are no clips, the case is moulded in one piece.

If your not comfortable doing them yourself, I dont mind doing it for a few beer notes

[neilGTI]

well i have 3 of them now, so i dont mind having a bash at one of them, but if i cant do it, i will certainly bear you in mind for fixing one of them.

Did you cut, chisel, prize apart ???

[neilGTI]

I have sorted mine out now, thanks for the pictures.

I used a dremel with a circular cutter on it to get it open and it missed the board by about 2mm, just gotta work out the best way to re-seal it now

[tegwin]

Good call with the dremel...

I glued the lid on with a couple of small blobs of araldite rapid, once it set I then used quite a lot of clear silicone wiped into the crack with an extra external layer to be doubly sure it was sealed!


Dont, whatever you do, get glue or sealant on the circuit board!

[neilGTI]

The dremel idea just popped into my head, apart from snapping one of the cutting blades, it was an easy way to get it open and only took about 5-10 minutes (and that was going slow because i didnt know where the board was).

Its amazing how just one bit of solder stops the thing working, definately a design fault in my eyes.

I am glad i never sent it off to a company on ebay for a refurb, they wanted £100+ for a job anyone could do with a bit of patience.

Gonna probably try and get it siliconed on the weekend if i can. Thinking of getting some carbon fibre sheeting around it too to try and dispel some of the heat and prevent it happening in future.

[tegwin]

I dont think the CF will help...

The issue is heat caused by the electonics inside the box, that coupled with vibration... not good... I used to service a mates guitar amp... every 6 months or so I had to resolder almost all of the joints for the transistors where the vibration and heat had cracked them open.... Was a known design floor with that amp, the tracks were slightly too small!

[sorted]

Same thing happened to mine - also done the same as you with the run of solder - i took pics as well, ill see if I can find them!!

PS... GTI doesnt have the same ABS Pump as the 1.4, as I bought one for a £10 - it fits but is missing 2 parts inside it!

[Tim_GTi]

Bumping an old thread, but I need to get this sorted on mine within the next week or so.

What did you guys use to reseal the unit?

EDIT: furthermore is there anything I need to consider when removing the unit? Do I need to disconnect the battery etc?

I don't know which part of the unit I'm removing yet, but I'm sure it'll become clear when I have a look. My understanding is that it's the blackbox which can be removed by unscrewing 4 bolts?