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HAS ANY ONE EXPIRENCED THIS ELECTRICAL PROBLEM !!!

Marksgd

New member
My Macan all of a sudden chimed & a warning came up from the instrument cluster saying ACC/PAS unavailable service required then saying engine control fault consult garage driving permitted???
It happend last sunday morning & was recovered to Porsche Tewkesbury who could not find anything wrong with it they said battery was a little down. so it was charged i picked it up thursday & today it has done exactly the same thing again....can anyone assist??


 
Adaptive Cruise Control is deactivated automatically if the radar sensor is very dirty or is covered in ice or by an obstacle, in unfavourable weather conditions (heavy rain) or when driving through tunnels.

The message "ACC/PAS not available” appears on the multi-function display of the instrument panel. Always keep the radar sensor clean and free of ice and snow to ensure that it is fully functional.
Regards,

Clive
 
Hi ,Yes i relise that but the senser is clean it then says engine fault drive to garage then goes back to acc/pas indicators will not work or full beam The garage say no fault found which is really strange. The car is just 3 years old serviced by Porsche you would not expect this from such a prestige car!!! Would You??
 
Only trying to help. :rolleyes: It's a complicated combo of mechanical and electronic systems that can go wrong no matter which marque it is.

Your best bet is to go back to your OPC, ask for a loan car and leave it with them until they can replicate the fault. Warning lights should produce fault codes that can be traced by their PIWIS.
Regards,

Clive
 
Hopefully there will be a fault code that shows .The Macan is being recovered back to Porsche in morning.
Looking around the WWW there seems to be a lot of people suffering same problem.

 
Marksgd said:
Hopefully there will be a fault code that shows .The Macan is being recovered back to Porsche in morning.
Looking around the WWW there seems to be a lot of people suffering same problem.



Apologies if I am coming into this debate at a late stage but I am relatively new to the Forum and thought I could get some advice from fellow Macan owners. I, too, am suffering the same fault. I have a March 2017 Macan S diesel and this fault PAS/ACC unavailability fault caption originally started very much intermittently and infrequently. It occurred only on start up and seemed to be cleared by switching the engine off, removing the keys and then restarting. Despite having a very pristine and clean radar (ACC) sensor and a similarly clean windscreen, this PAS/ACC unavailabilty fault now occurs on every start. I have reported it to my OPC on 3 occasions and they have not been able to discover any fault code or replicate the fault caption. Grateful for any thoughts
 
This is an interesting one. I had this occure last weekend for the first time on my Macan. The message appeared for about two minutes and then cleared, this happened two days running as I left a National Trust properties gate house. It has not happened again, I am just wondering whether it was RF interference for a security system.
Any thoughts?

Mike
 
mclark said:
This is an interesting one. I had this occure last weekend for the first time on my Macan. The message appeared for about two minutes and then cleared, this happened two days running as I left a National Trust properties gate house. It has not happened again, I am just wondering whether it was RF interference for a security system.
Any thoughts?

Mike
Are you referring to external interference? If so, then I have nothing, other than domestic wiring in or near my garage, and when the fault has displayed elsewhere, I was not aware of anything externally that could affect the car. Moreover, given that the car is a 'Faraday's Cage', I suspect it would take a powerful electrical transmission to affect the car's internal systems. So I would rule out external interference.

My view it is a software issue that needs resolving quickly as it affects some of the car's safety systems. I have referred my question to my local OPC and asked them to take it up with engineers at Porsche GB, Reading as well as fielding it to Germany. I now await a response.
 
[h2] [/h2][h2]yes, I was referring to external interference. I will be really interested in the response from your OPC. [/h2][h2] [/h2][h2]ACC uses the Doppler effect [/h2]
In order to determine the values required for the adaptive cruise control system, the vehicle is equipped with an ACC radar antenna with several radar sensors that are installed in the front of the vehicle. The measurement is physically based on the Doppler effect. The relative speed is determined by measuring the different wavelengths between the transmitted and reflected signal. If an object is moving towards the vehicle, for example, the frequency of the reflected wave increases. If the object moves away from the transmitter, the frequency decreases. A comparison of the two signal curves takes place in the sensor control unit (SCU), which is responsible for controlling the adaptive cruise control system. The SCU also houses the compact radar sensor unit and the electronic control unit (ECU) for the ACC system.

Whereas the first generation of adaptive cruise control monitored the measured area using three radar beams, with the centre radar beam being directed precisely forwards and the two side sensors each directed to the side at an angle of 2.5 angular degrees, second-generation ACC systems use four radar beams. This improves the entire horizontal measurement range of the radar sensor from ± 4 to ± 8 angular degrees. With a transmission frequency of 76 to 77 Gigahertz, the ACC sensor continuously scans an area of between 2 and 120 metres in front of the vehicle with a power of around 10 mW.
 
One other glitch in Porsche ECU fault reporting is when a coil pack starts to fail.
This throws all sorts of odd and seemingly unrelated fault messages to the dash.
When the packs start to fail its either when starting from cold or when the engineerings gets hot.

I might be way off base but I had issues with my Boxster GTS throwing odd fault codes and in the end it was discovered to be the coil pack issue at 3yrs old and 20K
 
Had a reply back from Porsche Garage yesterday still cannot find the problem only thing they did get was a "drain on the battery" but they still cannot find out where, as of yet!!. Will keep you posted but fear its going to be a while before they find the problem
 
mclark said:
Thank you of a very interesting scientific explanation of how ACC works; however, I regret your explanation does not help in determining what is causing these error signals and to what extent the safety systems are affected, namely ACC and PAS
[h2] [/h2][h2]yes, I was referring to external interference. I will be really interested in the response from your OPC. [/h2][h2] [/h2][h2]ACC uses the Doppler effect [/h2]
In order to determine the values required for the adaptive cruise control system, the vehicle is equipped with an ACC radar antenna with several radar sensors that are installed in the front of the vehicle. The measurement is physically based on the Doppler effect. The relative speed is determined by measuring the different wavelengths between the transmitted and reflected signal. If an object is moving towards the vehicle, for example, the frequency of the reflected wave increases. If the object moves away from the transmitter, the frequency decreases. A comparison of the two signal curves takes place in the sensor control unit (SCU), which is responsible for controlling the adaptive cruise control system. The SCU also houses the compact radar sensor unit and the electronic control unit (ECU) for the ACC system.

Whereas the first generation of adaptive cruise control monitored the measured area using three radar beams, with the centre radar beam being directed precisely forwards and the two side sensors each directed to the side at an angle of 2.5 angular degrees, second-generation ACC systems use four radar beams. This improves the entire horizontal measurement range of the radar sensor from ± 4 to ± 8 angular degrees. With a transmission frequency of 76 to 77 Gigahertz, the ACC sensor continuously scans an area of between 2 and 120 metres in front of the vehicle with a power of around 10 mW.


 
whinbush said:
One other glitch in Porsche ECU fault reporting is when a coil pack starts to fail.
This throws all sorts of odd and seemingly unrelated fault messages to the dash.
When the packs start to fail its either when starting from cold or when the engineerings gets hot.

I might be way off base but I had issues with my Boxster GTS throwing odd fault codes and in the end it was discovered to be the coil pack issue at 3yrs old and 20K
Thank you. Again this is a known problem, but the Macans affected by this particular fault code are both diesel and petrol, so I doubt whether a 'collapsing' coil pack would be the cause
 
Marksgd said:
Had a reply back from Porsche Garage yesterday still cannot find the problem only thing they did get was a "drain on the battery" but they still cannot find out where, as of yet!!. Will keep you posted but fear its going to be a while before they find the problem
I, too, use Tewkesbury as my OPC and the answers you are getting are very similar to the one's I previously received; hence I have asked the Service Manager there to raise this issue to a higher level, namely the engineers/trainers at Porsche GB, Reading and also to the factory in Germany. I am aware that some of the technicians at Tewkesbury are not particularly experienced with Porsche marques
 
Thats not filling me with confidence regarding the techs at Tewkesbury. I t would be interesting to see what Porsche GB Reading have to say!car has been there all week with no outcome really as of yet
 
Marksgd said:
Thats not filling me with confidence regarding the techs at Tewkesbury. I t would be interesting to see what Porsche GB Reading have to say!car has been there all week with no outcome really as of yet
No different to many other OPCs. Most of the techs come from other brands such as BMW, VW, Audi etc, so they are generally experienced techies but not with Porsche marques. Moreover, as with all modern cars, the techie's first port of call is via a vaz download and then see what the good book tells them. Not in the book, fault not known. That's where the engineering training dept at Reading comes into its own - they have a couple of chaps there who have been with Porsche for decades and what they don't know is not worth knowing!! Also the design/development engineers at the factory will have probably encountered such faults during testing and have either ironed them out via software changes or will be able to give an answer as to whether system safety is likely to be compromised
 
Woul
wilkey said:
Marksgd said:
Thats not filling me with confidence regarding the techs at Tewkesbury. I t would be interesting to see what Porsche GB Reading have to say!car has been there all week with no outcome really as of yet
No different to many other OPCs. Most of the techs come from other brands such as BMW, VW, Audi etc, so they are generally experienced techies but not with Porsche marques. Moreover, as with all modern cars, the techie's first port of call is via a vaz download and then see what the good book tells them. Not in the book, fault not known. That's where the engineering training dept at Reading comes into its own - they have a couple of chaps there who have been with Porsche for decades and what they don't know is not worth knowing!! Also the design/development engineers at the factory will have probably encountered such faults during testing and have either ironed them out via software changes or will be able to give an answer as to whether system safety is likely to be compromised
I would have thought that OPC would have spoke to Reading after a week of not knowing why this problem is ongoing? perhaps they have. I did mention to OPC Tewkesbury that there was more than a few people reporting the same symptoms, OPC replied "we try not to listen to forum talk"!!
 
Well after 0ver 4 weeks i have got the Macan back from OPC Tewkesbury The fault after 30 hours of diagnostics!!!! has been diagnosed as the "Front end electronic control unit".
I had contacted Porsche customer services regarding the cost of the work carried out, as the Macan was approx 5 weeks out of warranty. After talking to one of the personnel there regarding a "Gesture of Goodwill" Porsche said i will have to contribute £815.00 towards the cost . I said for a prestige Company like Porsche i think they could have done better. They were having none of it.....Why do i have to shore up the time cost it took the OPC to diagnose the fault??? .
A unhappy Porsche owner....Ps i hope this has cured it ....
 
That'll be half the cost of extending the warranty.
Cross fingers that nothing else goes wrong in the next 12 months and you'll be in pocket! [;)]
Regards,

Clive
 
Marksgd said:
Well after 0ver 4 weeks i have got the Macan back from OPC Tewkesbury The fault after 30 hours of diagnostics!!!! has been diagnosed as the "Front end electronic control unit".
I had contacted Porsche customer services regarding the cost of the work carried out, as the Macan was approx 5 weeks out of warranty. After talking to one of the personnel there regarding a "Gesture of Goodwill" Porsche said i will have to contribute £815.00 towards the cost . I said for a prestige Company like Porsche i think they could have done better. They were having none of it.....Why do i have to shore up the time cost it took the OPC to diagnose the fault??? .
A unhappy Porsche owner....Ps i hope this has cured it ....



MarkSGD

Really sorry to hear about your problems. Having owned a previous Porsche, my experience has been that, although on first inspection, an extended warranty appears expensive, when you strip out the European-wide recovery package, the warranty insurance is not that expensive over the two year period. At the time I bought my Cayman, the factory warranty lasted two year. I kept the car for 8 years and renewed the warranty during the entire period of my ownership. Two claims were made during that time which totalled over £2000 worth of work.

My similar problem to yours, namely the ACC/PAS Unavailable message illuminating appears to have been caused by a voltage drop on engine start when it was cranking at about 75rpm. This led to an inspection of the battery which appeared not to be holding charge (a loss of 25% over a 24 hour period). When the battery compartment was opened, it was full of water - 6 ltrs to be precise - which caused the battery terminals to corrode, as well as corrosion to the sub-woofer and several other electrical components. The leak was caused by the right rear sunroof drainage tube not being routed correctly to the external drain hole which caused water to ingress into the battery compartment. No-one can be sure but, given that nothing would have caused the pipe to be dislodged, it must have been like that since the day it was manufactured. I am very grateful to the senior technician at my OPC for his diligence - a couple of bottles of decent wine will be winging their way to him by way of thanks - he has prevented what appeared to be an innocuous problem from developing into something more serious.

I collected the car last Friday and, so far, the ACC/PAS Unavailable message has not re-appeared.
 

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