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mat59

996 Turbo ABS PSM warning - Pump Diagnosed faulty?

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Hi All,

 

My 2002 ROW 996 Turbo has the ABS and PSM warning. My specialist has advised I have fault codes 4266 and 0266. He has recommended I replace both the precharge pump and ABS pump at huge expense. He couldn't diagnose which of the two pumps, so I'm not very confident in him!

 

Any ideas what's causing the fault? I have no leaks and other than the warning, the car drives fine but I've driven it gently to avoid using ABS or PSM.

 

this is the message he gets from his diagnostic software:

 

Return pump fault

 

Diagnostic Conditions

 

- Return pump voltage and motor relay voltage actual values are evaluated and display implausible values.
- Open circuit in circuit to control module terminal 1.

 

Possible causes of fault

 

- return pump motor locked up/runs too easily
- Wire/plug connection faulty
- PSM hydraulic unit faulty

 

Thanks

 

Matt

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Before doing that, I would load test the battery and alternator on the car, and check the voltage drop across the primary battery cables.  These cars are prone to throw ABS and PSM faults when the battery and/or alternator act up, or when the resistance in the cables gets too high, and testing is much cheaper than jumping for some very expensive and possibly unneeded parts.

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I agree with JFP.

Check the age of your battery - if over 4 years then replace it.

Check the alternator output at the battery with the engine running - should be 13 volts or above.

 

Also, your tech's diagnostic software results do not agree with Porsche's.

 

4266.jpg

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Thanks guys. I replaced the battery a few months back and alternator last year. The batt was at least the spec of the original one and possibly higher.

 

I will get the wiring tested but it does point towards the pump. 

 

Do do you know if they can be refurbished?

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Right, assuming it is the pump I have found a used replacement which is also from a 2001 built 996 Turbo. Problem is the part number of the replacement is 99635595558 and my garage is using saying I need to replace with  99635595563. I asswould me these are the same part with a slightly updated part number. Do you know if it can be coded to my car?

 

Thanks,

 

Matt

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Sorry for the confusing message. My part number is 99635595563 and the used replacement item is 99635595558 so I'd be replacing with a part with a lower number

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2 hours ago, Loren said:

Generally that is not a good idea.

The -63 is the latest part.

Thanks. Have a feeling they have told me the newer number as this is what shows up as a replacement rather than what is actually stamped on the part.

 

It's now at a specialist's with better diagnostic equipment

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So, I've found that my ABS pump on my car is porsche part number 99635575559. Not many used units for sale but I have found one used unit with nearly the same number, although this one ends in 8 so one number off. The two other numbers on both of the pumps match - 0265225101 (engraved next to the porsche no.) and 0265950043 (on the sticker). They look identical.

 

A few posts back Loren, who's given me great advice before, has advised that changing out a part for one with a lower number may not work. Do you still advise this given the new info I've given above.

 

Not wishing to second guess an expert here but as the Bosch numbers are the same and they look identical I'm optimistic.

 

Failing this, I will look at sending it off for a rebuild. Anyone know if this can be done?

 

I've contacted a few firms that rebuild ABS pumps but they haven't done a 996 turbo pump before but we're confident they'd be able to.

 

Many thanks!

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I would stick with Loren's advice.   When a manufacturer replaces a part with a superseded number (read higher), it is typically because they have found a defect or problem with the earlier unit.  Quite often, these updated units carry multiple upgrades that have accumulated since the original release (updated pressure settings, orifice sizes, etc.) to correct faults or failures.  It is also not unusual for electronic systems in the car to need to be recoded to optimize the updated mechanical system's performance.  Going backwards can create difficult problems, some of which are insurmountable.  As for the Bosch numbers, they can easily represent the housing, and not the contents, as updated components are often visually exactly the same, but work differently.

 

If you cannot source the newer updated unit, get yours rebuilt.

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I do not really know, but I assume so as there are core charges when replacing existing units with replacements.  That said, there are many OEM systems that carry core charges where only the factory can rebuild the component.  The PDK transmission is a good example.

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It turns out my ABS pump is leaking hydraulic fluid so on speaking to the various places that rebuild these pumps, they have said it cannot be rebuilt. I have sourced both a used unit, with part number ending 63 instead of mine ending 59 (superseded part) and a brand new Bosch (porsche supplier) unit. The suppliers of the brand new unit say that it will need to be coded to the car. Does anyone know the level of coding required or is it straightforward? Now just trying to find someone that will fit it.

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Had the refurbished pump fitted by a mechanic with autologic diagnostic equipment, which has coding functionality for porsche. Seems to have worked as I haven't seen the ABS warning since. The refurbished pump was sourced through BBA reman in UK. They sourced it from Bosch I believe, who did the refurb. It has a lifetime warranty. The replacement pump had porsche part number that ended in 58 but my pump ended 59. Still seemed to work but don't know if anything was done to it by Bosch to make it work on my car.

 

just thought I'd follow up as a reference for anyone that has this prob in the future.

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2001  996 TT ABS PSM warning light came on. Long story short, every shop(non Porsche) said the pump/computer was bad and needed replacement 4,000.00>. I don’t have a Porsche dealer anywhere around so I just listened and watched. Come to find out the tire pressure was low, adjusted pressure and lights went out. 

Question, how did it know the tire pressure was low, there is no TPMS system that Iam aware of???  Curious and new to Porsche.

 

1st Porsche I have owned and concerned about the car diagnostic,   Best to invest in  Durametric Diagnostic Tool.  

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19 minutes ago, Allan.adams said:

2001  996 TT ABS PSM warning light came on. Long story short, every shop(non Porsche) said the pump/computer was bad and needed replacement 4,000.00>. I don’t have a Porsche dealer anywhere around so I just listened and watched. Come to find out the tire pressure was low, adjusted pressure and lights went out. 

Question, how did it know the tire pressure was low, there is no TPMS system that Iam aware of???  Curious and new to Porsche.

 

1st Porsche I have owned and concerned about the car diagnostic,   Best to invest in Durametric Diagnostic Tool.  

 

Your ABS/ PSM system monitors relative wheel rotational speeds; if one tire is low on air, its diameter is different enough for the system to see rotational speed difference and trigger the system.  Same thing would happen with mismatched tire sizes.

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Very lucky, my 2000 996C4 got the code 4266 recently, battery is good condition which had been tested. Car runs good every morning, but after drive 30mins~1 hour the ABS + PSM light on.   

When back home, let the car sit over night, it come back normal. I really hope this problem is not come from  ABS control unit, but seems it does.

I read the part number printed on my ABS control unit is 996 355 755 47, but the parts catalog shows 996 355 955 47?

Any alternate part number for my MY2000 996C4 or newer one I could use?

Thanks

 

Edited by George996C4
typo

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HI!

 

Car is 2002 996 turbo.

 

I've got code 4266 also. They come and go. From the above:

 

Possible causes of fault

 

- return pump motor locked up/runs too easily
- Wire/plug connection faulty
- PSM hydraulic unit faulty

 

What does "return pump motor locked up/runs too easily" mean? Is the motor a separate unit, inside the pump, or...? Is this item a repairable thing?

 

Thanks!

 

CW

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1 hour ago, porsche996tt_tpe said:

HI!

 

Car is 2002 996 turbo.

 

I've got code 4266 also. They come and go. From the above:

 

Possible causes of fault

 

- return pump motor locked up/runs too easily
- Wire/plug connection faulty
- PSM hydraulic unit faulty

 

What does "return pump motor locked up/runs too easily" mean? Is the motor a separate unit, inside the pump, or...? Is this item a repairable thing?

 

Thanks!

 

CW

 

The electric motor is internal to the pump, and is not available as an individual part, the entire unit would need to be replaced.

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ok. from an elec engineering point of view, from what I can see, the pump can not be repaired or at least repaired easily. so why not use another cheap Borsch-made pump and graft the electronic board over? I just don't think Bosch would make an entirely unique part for 996 turbo, the best is having a unique board that defies compatibility. 

 

any thoughts or am I just day-dreaming... 

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1 hour ago, porsche996tt_tpe said:

ok. from an elec engineering point of view, from what I can see, the pump can not be repaired or at least repaired easily. so why not use another cheap Borsch-made pump and graft the electronic board over? I just don't think Bosch would make an entirely unique part for 996 turbo, the best is having a unique board that defies compatibility. 

 

any thoughts or am I just day-dreaming... 

 

Usually because it would be a waste of time and money, and you would end up with a "Frankenstein" system that would ultimately lower the car's value.

 

Most people would also want the very best for any system that their life could hinge upon;  "If you have a ten dollar head, buy a ten dollar helmet; but if your head is more valuable to you, act accordingly...………………….…….."  :rolleyes:

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