996 Turbo ABS 'world of pain'

[GeeBeeMan]

if anyone can point me towards some comprehensive ABS advice......please do!!!!! so far - and trying to keep it brief........

I'm a month into it since I needed rescuing on a flatbed after the brakes locked on. the vehicle's at Noble Motorsport (Chesterfield)

tests point towards a faulty ABS assembly (ie either the electronics or the pump itself)

the assembly had a 1 week 'holiday' at BBA Reman in Kent - but came back untested from what I understand

a new one is £2k from OPC, £1k but 'long wait' / special order from Bosch themselves, or £750 do you feel lucky punk? second-hand

Bosch offer an electronics test facility in Germany - but it's hard to comprehend the protocol of how you get it back to them.....and then they appeared to insist on error codes, which at that point I didn't have

I now have the error codes and we'll soon know whether Bosch will accept it back to have a look. the codes are:-

4460 pressure sensor / 5504 emergency brake / 4206 speed sensor front left. think the last one is a red-herring to do with the car being on a lift

so far I have Googled for England, taken advice from TIPEC's technical officer and anyone else who might be prepared to listen, scratched my head, and got very frustrated with it all

thanks



GeeBeeMan

[Rockster]

Outright ABS failure, be it the hardware or the controller is rare.

I do not quite understand your desire to send ABS unit to Bosch. I would have thought the factory manual would be clear on this and the test/diagnostics procedures called for the error codes would have had the tech id the offending part or the major component and this would be replaced.

The question then becomes from where to source the hardware that needs to be replaced. With something like an ABS pump or controller given its safety critical function I would not skimp. The unit is not easy to replace and to guard against getting a faulty replacement I would go with a new one and one that came with a warranty against defective parts or workmanship.

[GeeBeeMan]

T H A N K Y O U

The desire to send the unit to Bosch is based on not having a better idea to be honest. If you Googled 'Bosch Electronic Repair Service' - you'd find a fairly slick-looking website, and if it can be repaired it has to be better than £2k (but off the shelf) or even £1k and 14 week wait

[Rockster]

GeeBeeMan said:

T H A N K Y O U

The desire to send the unit to Bosch is based on not having a better idea to be honest. If you Googled 'Bosch Electronic Repair Service' - you'd find a fairly slick-looking website, and if it can be repaired it has to be better than £2k (but off the shelf) or even £1k and 14 week wait

Oh, I was not aware there was a repair service. If reputable this could be a serious money saver compared to having the unit replaced with a new one.

Oh, I did google the search term and you are right. The web site:

https://www.bosch-repair-service.com/DE_en/Welcome...

looks very slick and more important the repair service looks to be something associated closely with Bosch. I like. Bookmarked it.

Good luck.

[smj996c]

another possible cause is a failed reluctor ring or speed sensor. the reluctor rings corrode and break, obviously if one fails then it will affect your ABS system.

[Rockster]

smj996c said:

another possible cause is a failed reluctor ring or speed sensor. the reluctor rings corrode and break, obviously if one fails then it will affect your ABS system.

This is a good point.

While I tend to in this case discount the sensor error with the reasoning (err fancy name for WAG'ing) that a faulty sensor would not cause the brakes to lock up and the other error codes pointing to something deeper than a wheel speed sensor, really the OP should avail himself of a professional tech and one quite capable of diagnosing at least the extent of the problem. I would hate it, were I in the OP's position, to go to the trouble of removing the ABS system, sending it to Bosch to be repaired, then upon its return installing the unit, bleeding the system, doing whatever else it takes to get the system back into the car and the car once again operational only to find the same behavior is still present and then learn it was a wheel speed sensor all along.

[GeeBeeMan]

we're beyond my technical understanding now but...........the car has been road-tested more than once apparently with the ABS unit disconnected/by-passed call it what you will......and runs fine without it. Wouldn't this rule out 'reluctors' / sensors' etc etc?

[mr pg]

I share your pain, having had the same happen on my 996T a year or so ago. New unit fitted by OPC at I think from memory £2.4k (that included a sizeable discount!). Thankfully mine went just going to local supermarket, rather than on the motorway, or similar. I still have the old pump, which I mean to find out if I can get something for with companies who refurb them.

[cd1957]

Hi fault code info below:
4460=short to ground/positive,open circuit on pins 25/26 or 42
plug on brake light switch
stoplight switch fault
wiring/connection to internal pressure sensor (replace abs unit)

5504=erase and test drive

Chris in Cardiff

[pete.g]

There are units on ebay for a lot less than £750. Why not fit one of these and send your own back to Bosch?

Then when yours is refurbed refit it and resell the ebay unit - at least this way you get to drive the car and you'll have a unit that's been checked out by the manufacturer.

Genuine speed sensors aren't expensive either if your does need replaced.

[GeeBeeMan]

The inexpensive pumps on FleaBay aren't for a Turbo (sadly!!!) Pump seems to be exclusive to that model

[smj996c]

GeeBeeMan said:

we're beyond my technical understanding now but...........the car has been road-tested more than once apparently with the ABS unit disconnected/by-passed call it what you will......and runs fine without it. Wouldn't this rule out 'reluctors' / sensors' etc etc?

Not necessarily, I'm simply suggesting you check all items that provide input (reluctors, Speed sensors, Brake pedal switches) to your ABS system before swapping the ABS system itself.