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Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15555
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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I've got a problem with DSC on my Jaguar S-type 2.5 V6,

Customer Question

Hi Richard,I've got a problem with DSC on my Jaguar S-type 2.5 V6, automatic, RHD, MY2005
I'm hoping that you might have across similar fault.On turning the ignition ON, there is no fault.
Car starts and drives as normal but upon taking off, over 50 km/h the "DSC not available" message appears. Every time the same way in the last few months.Brakes work as normal
ABS kicks in even with the DSC message on displayI checked for the clues via SDD and it comes with C1777 vacuum pressure circuit failure. According to the workshop, it's either brake booster or ABS/DSC moduleI checked the booster so:
With engine OFF pedal is hard
With engine on pedal is soft
Upon switching engine off and with foot firm on pedal, it goes up within about 10 seconds.The Brake Master cylinder operates normally, with pedal depressed it stops half way (engine running) and doesn't sink to the floor.Brake switch on pedal working ok and calibrated with SDD to make sure all ok. Rear lights working as normal when pedal depressed.Car already had this problem when I bought it.
Submitted: 2 months ago.
Category: Jaguar
Expert:  Richard replied 2 months ago.
HelloCan I have the last six digits if your VIN?
Customer: replied 2 months ago.
Hi Richard,The last digits are N21070.
Full VIN is SAJAC02N65JN21070
Customer: replied 2 months ago.
Hi Richard,Did you have a chance to look into this?
Expert:  Richard replied 2 months ago.

Ok looks like the most likely cause is the brake booster. It has the internal solenoid as well as the force and travel sensors. If a new or used one is installed it will need to be calibrated ith the SDD. To recalibrate you will need to program the ABS/Trac system. It will also calibrate the steering angle sensor. I also recommend monitoring the wheel wpeed sensors on datalogger on the SDD just in case.

Let me know.

Customer: replied 2 months ago.
Hi Richard,I checked the ABS sensors readings on the datallogger and they all come ok.Would you know the procedure to check sensors and actuators etc on the brake booster? It's functioning correctly as is the rest of the system up to about 50km/h (ABS works fine even if DSC light is lit). I thought that if there was a problem with brake booster, it would manifest itself at power up self test and intialization of sensors on it including communication with the DSC module?
Expert:  Richard replied 2 months ago.

With SDD we can perform a configuration to recalibrate the booster. If it is not under your service function/setup and configuration then you may need to reprogram the ABS module.

Customer: replied 2 months ago.
I've already tried it but unfortunately it didn't work.
I re-calibrated the brake sensor using SDD and re-programmed the ABS module (DSC) successfully, no change, the "DSC not available" still appears on the speedo if driving over 50 km/h