BMW 745i Dynamic Drive

David Mechanic United Kingdom Posted   Latest   Edited  
Resolved
Chassis
2003 BMW 745i 4.4L (N62) 6-spd

Hi , hoping for some help please. 2003 BMW 745i with Dynamic Drive Vin : WBAGL62090DJ93938, 78106 miles.

Fault code : 5D5C: ARS: Pressure Build-up, Rear Axle, Faulty.

Vehicle came to me with a power steering leak the CHF oil was spurting out under high pressure from the hose Banjo where it connects to pressure accumulator on the tandem pump.

The banjo bolt was tight, so i removed and inspected the banjo union and sealing washers. All looked ok so i replaced the 2 aluminium sealing washers with Dowty seals and torqued up the Banjo bolt, toped up the fluid and bled the system ( turning lock to lock ) and cleared the fault codes, Zeroed the sensors ( using Launch X413 pro )carried out a ARS Startup. Road tested the vehicle and the Dynamic Drive warning light illuminated. The vehicle was driving well so i let the vehicle go intending to reschedule a time for further diagnosis. At the back of my mind i thought that the system could have over pressurised.

Four days Later i get a call to tell me that the fluid had leaked again. Upon inspection it was leaking from the same place but this time the Banjo bolt was loose. I have replaced the Dowty seals again just so i can move the vehicle, i have ordered some new sealing washers from the agents just in case the Dowty seals don't mix with the CHF oil.

I have been told that if the filter in the CHF reservoir is blocked it can causes the system to over pressurise and that one of the 3 hoses listed as expansion hoses has a built in filter but don't know which one , the main dealers don't know either. 

I intend to do a visual inspection of the valve block and control module wiring hoping to find some corrosion or damage.

Any help or direction would be much appreciated, thanks in advance. Dave T….

PS i almost forgot to add that a module scan said that the vehicle is not equipped with ABS which it clearly is and i can not communicate with the ABS. I will try another scanner. any ideas on this one please…

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Reginald Owner/Technician
Georgia
Reginald
   

were you able to 0 the pressures on the axles? Make sure the axle pressures and reset and zero before bringing ARS back online​.​The reservoir isnt blocked if it was it would have never allowed you to get into the ARS system,. Also please tell send me all the codes in the DSC…You must have DSC communication in order for the system to work. check the harness pins for corrosion at dsc module, If…

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David Mechanic
United Kingdom
David
 

Reginald thank you ! Hopefully i will be able to get the vehicle back to the workshop over the weekend and do the tests as advised. Looking back over the saved diagnostic reports i find that on some the ABS ( Anti-lock braking system ) is listed and reported normal where as on others its not even listed. Also when i choose to enter the ABS Module the scan tool reports it as not equipped ! I will…

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David Mechanic
United Kingdom
David
 

Reginald, a update on the dynamic drive issue . I don’t want to confirm a fix as yet as time will tell if it’s truly fixed . I managed to get the pipe sealed at the banjo bolt connection at the tandem pump. I had to resurface the pipe banjo mating surfaces and use the bmw sealing washers and a coating of Wellseal . I learned some thing about Dowty seals the standard seal ( nitrile )are good…

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David Mechanic
United Kingdom
David
 

Spoke to the owner today and so far so good. So I am tentatively classing this as resolved . I would like to thank Reginald for his help. Regards Dave T…

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David Mechanic
United Kingdom
David Resolution
 

Hi , see my reply to Reginald explaining the fix . Thanks for your help Reginald ! Regards Dave T.

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Resolution Ð Awarded