Speedometer Calibration

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rotorhead23

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I have a 2010 Jetta TDI Highline and the speedo is 8% fast. I tried changing the multiplier number. Tried every one except 0. All the others seem to be for specific vehicles, some European. What does the 0 do? Is there something I am not doing?
 
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rotorhead23

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Code:
Thursday,13,March,2014,15:57:10:54235
VCDS -- Windows Based VAG/VAS Emulator
VCDS Version: 12.12.2.0
Data version: 20140212


VIN: 3VWRL8AJXAM138645   License Plate: PSX005



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: AJ (1K0)
Scan: 01 03 08 09 15 16 17 19 1C 25 2E 42 44 46 52 56 62 72 77

VIN: 3VWRL8AJXAM138645   

01-Engine -- Status: Malfunction 0010
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: Sporadic communication error 1000
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: Malfunction 0010
19-CAN Gateway -- Status: Malfunction 0010
1C-Position Sensing -- Status: Malfunction 0010
25-Immobilizer -- Status: OK 0000
2E-Media Player 3 -- Status: OK 0000
42-Door Elect, Driver -- Status: Sporadic communication error 1000
44-Steering Assist -- Status: Malfunction 0010
46-Central Conv. -- Status: OK 0000
52-Door Elect, Pass. -- Status: Sporadic communication error 1000
56-Radio -- Status: OK 0000
62-Door, Rear Left -- Status: Sporadic communication error 1000
72-Door, Rear Right -- Status: Sporadic communication error 1000
77-Telephone -- Status: OK 0000
 
-------------------------------------------------------------------------------
Address 01: Engine (CJA)       Labels: 03L-906-022-CBE.clb
   Part No SW: 03L 906 019 CL    HW: 03L 906 022 TS
   Component: R4 2,0L EDC 0000SG  7966  
   Revision: 12H03---    Serial number:               
   Coding: 0350072
   Shop #: WSC 91579 999 100107
   VCID: 77D3003F061E9FA6AAD-8022

1 Fault Found:
005784 - Please Check DTC Memory of Steering Wheel Electronics 
               P1698 - 000 -  - Intermittent
             Freeze Frame:
                    Fault Status: 00100000
                    Fault Priority: 6
                    Fault Frequency: 5
                    Reset counter: 255
                    Mileage: 134237 km
                    Time Indication: 0
                    Date: 2042.14.15
                    Time: 12:48:59

             Freeze Frame:
                    RPM: 0 /min
                    Speed: 0.0 km/h
                    Load: 0.0 %
                    Speed: 0.0 km/h
                    (no units): 255.0
                    (no units): 255.0
                    Bin. Bits: 01000000

Readiness: 0 0 0 0 1 

-------------------------------------------------------------------------------
Address 03: ABS Brakes (J104)       Labels: 1K0-907-379-60EC1F.clb
   Part No SW: 1K0 907 379 AH    HW: 1K0 907 379 AH
   Component: ESP MK60EC1   H30 0107  
   Revision: 00H30001    
   Coding: 114B400C49250002881102E8921E0042300000
   Shop #: WSC 00066 000 00000
   VCID: 78D10303CB0090DEA37-802D

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC (J301)       Labels: 3C8-907-336.clb
   Part No SW: 3C8 907 336 AC    HW: 3C8 907 336 AC
   Component: Climatic      H14 0305  
   Revision: 00009001    
   Coding: 0000000002
   Shop #: WSC 00066 000 00147
   ASAM Dataset: EV_Climatic A01005
   ROD: EV_ClimaBasis_SE36.rod
   VCID: 6EFD255BB144DE6E79B-803B

No fault code found.

-------------------------------------------------------------------------------
Address 09: Cent. Elect. (J519)       Labels: 1K0-937-08x-09.clb
   Part No SW: 5K0 937 084 C    HW: 5K0 937 084 C
   Component: BCM PQ35 B    011 0029  
   Revision: BG011001    
   Coding: 2D200B1E902F3EE4000800854000000401000086500085605C8020000000
   Shop #: WSC 00066 000 00000
   VCID: 3245F12B6DFCBA8E5D3-8067

   Subsystem 1 - Part No: 1K1 955 119 F  Labels: 1KX-955-119.CLB
   Component: Wischer 20051  23  0512 
   Coding: 009795

2 Faults Found:
02394 - Parking Light Left Front (M1) 
            010 - Open or Short to Plus - Intermittent
             Freeze Frame:
                    Fault Status: 00101010
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 249
                    Mileage: 134242 km
                    Time Indication: 0
                    Date: 2042.14.15
                    Time: 17:31:11

             Freeze Frame:
                        Term 15 On
                    Voltage: 14.15 V
                        ON
                        ON
                        OFF
                        OFF
                        OFF

03384 - Windshield Washer Jet Heating 
            010 - Open or Short to Plus - Intermittent
             Freeze Frame:
                    Fault Status: 00101010
                    Fault Priority: 4
                    Fault Frequency: 7
                    Reset counter: 254
                    Mileage: 134237 km
                    Time Indication: 0
                    Date: 2042.14.15
                    Time: 00:06:08

             Freeze Frame:
                        Term 15 On
                    Voltage: 11.60 V
                        ON
                        ON
                        OFF
                        OFF
                        OFF


-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 1K0-909-605.lbl
   Part No SW: 1K0 909 605 AD    HW: 1K0 909 605 AD
   Component: 08 AIRBAG VW8R  036 8900  
   Revision: 06036000    Serial number: 003EVM02VZX%  
   Coding: 0012344
   Shop #: WSC 00066 000 00000
   VCID: 6EFD255B7944DE6E79B-803B

   Subsystem 1 - Serial number: 6332MSME52710A578

   Subsystem 2 - Serial number: 6342MSME52707809A

   Subsystem 3 - Serial number: 6351HSME206E685FN

   Subsystem 4 - Serial number: 6361HSME206E6E7AR

   Subsystem 5 - Serial number: 63727SME21320841O

   Subsystem 6 - Serial number: 63827SME21333347U

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel        Labels: 1K0-953-549-MY9.lbl
   Part No SW: 1K0 953 549 CD    HW: 1K0 953 549 CD
   Component: J0527           056 0111  
   Coding: 0000731
   Shop #: WSC 00066 000 00000
   VCID: 76CD0D3B0114E6AEB1B-8023

   Subsystem 1 - Part No: 5K0 959 542   Labels: 3C8-959-537.CLB
   Component: E221__MFL-TAS   H05 0010  
   Coding: 00000130
   Shop #: WSC 00000  

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments (J285)       Labels: 5K0-920-xxx-17.clb
   Part No SW: 5M0 920 870 E    HW: 5M0 920 870 E
   Component: KOMBI         H05 0305  
   Serial number: 00000000000000
   Coding: 371F00
   Shop #: WSC 00066 000 00147
   ASAM Dataset: EV_Kombi_UDS_VDD_RM09 A04052
   ROD: EV_Kombi_UDS_VDD_RM09_VW21.rod
   VCID: 3147FE2760FA8196249-8064

1 Fault Found:
12604928 - Combination / Chassis CAN Bus (SAE Bus D) 
          U0056 00 [008] - Performance
          Intermittent - Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 6
                    Fault Frequency: 1
                    Reset counter: 236
                    Mileage: 133887 km
                    Date: 2042.14.03
                    Time: 12:55:57


-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 1K0-907-530-V4.clb
   Part No SW: 1K0 907 530 AD    HW: 1K0 907 951 
   Component: J533  Gateway   H07 0112  
   Revision:   H07 01    Serial number: 300410F1000426
   Coding: E9807F06001612001002
   Shop #: WSC 00066 000 00000
   VCID: 69F7564740AA39562C9-803C

5 Faults Found:
01331 - Door Control Module; Driver Side (J386) 
            004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00110100
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 238
                    Mileage: 134015 km
                    Time Indication: 0
                    Date: 2042.14.10
                    Time: 00:00:06

01332 - Door Control Module; Passenger Side (J387) 
            004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00110100
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 238
                    Mileage: 134015 km
                    Time Indication: 0
                    Date: 2042.14.10
                    Time: 00:00:06

01333 - Door Control Module; Rear Left (J388) 
            004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00110100
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 238
                    Mileage: 134015 km
                    Time Indication: 0
                    Date: 2042.14.10
                    Time: 00:00:06

01334 - Door Control Module; Rear Right (J389) 
            004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00110100
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 238
                    Mileage: 134015 km
                    Time Indication: 0
                    Date: 2042.14.10
                    Time: 00:00:06

01320 - Control Module for Climatronic (J255) 
            004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00110100
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 238
                    Mileage: 134015 km
                    Time Indication: 0
                    Date: 2042.14.10
                    Time: 00:00:06


-------------------------------------------------------------------------------
Address 1C: Position Sensing        Labels: 1Kx-919-xxx-1C.lbl
   Part No SW: 1K5 919 965 D    HW: 1K5 919 965 D
   Component: Kompass         001 0001  
   Revision: 00001000    Serial number: 1293324R4X2706
   Coding: 0000004
   Shop #: WSC 00066 000 00000
   VCID: 3C59DF137FB87CFE87F-8069

1 Fault Found:
01299 - Diagnostic Interface for Data Bus (J533) 
            004 - No Signal/Communication - Intermittent
             Freeze Frame:
                    Fault Status: 00100100
                    Fault Priority: 3
                    Fault Frequency: 1
                    Reset counter: 236
                    Time Indication: 0


-------------------------------------------------------------------------------
Address 25: Immobilizer (J334)       Labels: 5K0-920-xxx-25.clb
   Part No SW: 5K0 953 234     HW: 5K0 953 234 
   Component: IMMO          H05 0305  
   Serial number:               
   Coding: 000000
   Shop #: WSC 00000 000 00000
   ASAM Dataset: EV_Immo_UDS_VDD_RM09 A03005
   ROD: EV_Immo_UDS_VDD_RM09_SE36.rod
   VCID: EAF5A94B0DACB24EA53-80BF

No fault code found.

-------------------------------------------------------------------------------
Address 2E: Media Player 3 (J650)       Labels: 5N0-035-342.lbl
   Part No SW: 5N0 035 342 B    HW: 5N0 035 342 B
   Component: SG EXT.PLAYER H13 0090  
   Revision: A1001003    Serial number: 7667908992    
   Coding: 010000
   Shop #: WSC 00066 000 00000
   VCID: 266D1D7B5134D62EC1B-8073

No fault code found.

-------------------------------------------------------------------------------
Address 42: Door Elect, Driver (J386)       Labels: 3C0-959-70X-GEN4.clb
   Part No SW: 3C0 959 701 B    HW: 3C0 959 793 
   Component: TUER-SG FT    002 0307  
   Revision: 13101005    Serial number: 0000849589
   Coding: 0004B5
   Shop #: WSC 01383 790 50316
   ASAM Dataset: EV_DCU42BroseDriveSide A03004
   ROD: EV_DCU42BroseDriveSide.rod
   VCID: 2773107F5E3ECF26FAD-8072

   Slave Driver: 
   Subsystem 1 - Part No SW: 1K0 959 703 AH    HW: 1K0 959 795 T  Labels: 1K0-959-70X-GEN4.CLB
   Component: J388__TSG-HL  006 1401 
   Serial number: 00000004824191      
   Coding: 000490

No fault code found.

-------------------------------------------------------------------------------
Address 44: Steering Assist        Labels: 1Kx-909-14x-44.clb
   Part No: 1K0 909 144 J
   Component: EPS_ZFLS Kl. 70     3001  
   Revision: 00H17000    
   Shop #: WSC 02069 000 90108
   VCID: 3147FE27A8FA8196249-8064

1 Fault Found:
03803 - Steering Angle Sensor for Steering Aid 
            000 - - - MIL ON
             Freeze Frame:
                    Fault Status: 11100000
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 255
                    Time Indication: 0

             Freeze Frame:
                    Battery Volts: 12.4 V
                        PD
                    Temperature: 8.0°C
                    Count: 2
                    Steering Angle: 0.00°
                    Count: 0
                        SteerAng n.Init


-------------------------------------------------------------------------------
Address 52: Door Elect, Pass. (J387)       Labels: 3C0-959-70X-GEN4.clb
   Part No SW: 3C0 959 702 B    HW: 3C0 959 792 
   Component: TUER-SG BT    002 0307  
   Revision: 15101005    Serial number: 0000730005
   Coding: 0004B4
   Shop #: WSC 01383 790 50316
   ASAM Dataset: EV_DCU52BrosePasseSide A03004
   ROD: EV_DCU52BrosePasseSide.rod
   VCID: 287113435320C05EF37-807D

   Slave Passenger: 
   Subsystem 1 - Part No SW: 1K0 959 704 AH    HW: 1K0 959 794 T  Labels: 1K0-959-70X-GEN4.CLB
   Component: J389__TSG-HR  006 1401 
   Serial number: 00000004809336      
   Coding: 000490

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio (J503)       Labels: 5M0-035-1xx-56.clb
   Part No SW: 1K0 035 180 AC    HW: 1K0 035 180 AC
   Component: Radio Prem-8  H10 0035  
   Revision: -----20S    Serial number: VWZ4Z7K3077759
   Coding: 2100040004
   Shop #: WSC 00066 000 00000
   VCID: 61E74E67789A7116F49-8034

No fault code found.

-------------------------------------------------------------------------------
Address 77: Telephone        Labels: 5P0-862-335.lbl
   Part No SW: 1Z0 035 729 E    HW: 1Z0 035 729 E
   Component: FSE_2P8x        H40 0190  
   Revision: 00000000    Serial number: 00000005248271
   Coding: 0013088
   Shop #: WSC 00066 000 00000
   VCID: 3A55D90B758C42CE953-806F

No fault code found.

End   ---------------------------------------------------------------------
 
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   #4  

rotorhead23

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All faults in above scan are fixed except windshield washer nozzle heaters.
 
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DrPeter

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Hi, thanks for posting the Auto-Scan...

It looks like the Distance Impulse Number number '0,3 and 8' are just not documented for any particular vehicle, where as the numbers '1, 2,4,5,6 and 7' are.

So if your cluster accepts the coding change you will not hurt anything by trying.

If your cluster does not accept any particular value, VCDS nor the factory scan tool can force it to do so.

The label file we use for that cluster also works for other clusters that maybe installed on different vehicle types, so coding changes will need to apply to those vehicles and these changes may not work on yours.

Hope this helps.. .

drpeter
 
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   #6  

Sebastian

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To understand how to do the calibration you have to understand how the values are being used/calculated. First off, a wheel/tire does a certain number of turns per kilometer. Depending on the wheel circumference (and therefor tire size/dimension) that number obviously differs. Check this thread in another forum... :)

http://forums.tdiclub.com/showthread.php?t=316833

In your case, you should be able to determine which coding values corresponds with which distance impulse number by reading the "Velocity Detection - Distance Impulses" adaptation channel in the instrument cluster.
 
   #7  

rotorhead23

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Thank you. I know how the impulse number works and understand how different wheel diameters affect the speedometer. I was surprised to see that most of the settings were for specific models. None of the settings did anything except make the speedometer read even faster. I will try the 0 setting to see if it will do anything. Looks like VW doesn't want us to have an accurate spedo. Being an ex helicopter pilot who has always needed accurate speed info kind of infuriates me. Let you know what the 0 does.
 
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Sebastian

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IMO the best way to approach this is by starting a list of coding values vs. actual distance impulse numbers (see the mentioned adaptation channel), this should give you a quicker overview about what is and isn't available resulting in an informed decision instead of blind trial and error. The fact that we currently have associated specific models with each of the coding values is merely a suggestion to our customers because different models simply come with different wheel sizes. :)
 
   #9  

In My Garage

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I have a 2010 Jetta TDI Highline and the speedo is 8% fast.
That is exactly how far mine is off on my 2013 Jetta Comfortline. 100 kph on the GPS is 108 kph on my analog speedometer and 106 kph on my digital display.

I tried changing the multiplier number. Tried every one except 0. All the others seem to be for specific vehicles, some European. What does the 0 do? Is there something I am not doing?
I just came back from trying all of them from 0 to 8. The 0 came back with a "Coding Rejected".

Some screen shots I took. By the way, Distance Impulse Number 7 is how my car came.





GPS readings were done with the cruise control set and on a level and straight section of highway.

Nr. - Analog - Digital
1 - 116 - 113
2 - 113 - 112
3 - 111 - 110
4 - 110 - 109
5 - 109 - 107
6 - 108 - 106
7 - 108 - 106
8 - 106 - 104
 
   #10  

jyoung8607

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That is exactly how far mine is off on my 2013 Jetta Comfortline. 100 kph on the GPS is 108 kph on my analog speedometer and 106 kph on my digital display.
There's two separate things to keep track of: how fast does the car think it's going, and what shows up on the analog speedometer needle. There's definitely a small, positive error designed into the analog needle display. This is present on all VWs. Any given measurement instrument will have an error band of non-zero width, and it's important this particular one never reads low for obvious legal reasons, so they deliberately design for it to err just a touch on the high side.

Underlying that, the car still should have a pretty good idea of how fast it's going. It's been a very long time since I tried this, but I seem to recall both of my cars being pretty close to dead-on as compared to GPS. I tested in a way very similar to yours. I set the cruise at a nice round speed, and then noted the position of the analog needle as compared to my trip-meter average speed display, which I reset after setting the cruise. The average speed display should show exactly how fast the car thinks it's going without the analog needle error. Alternatively, you could log speed from the instrument cluster with VCDS.

You seem to have a decent amount of error in the vehicle measured speed, and of course the analog needle error is cumulative with that. Given that your car seems to be coded properly, that doesn't seem like a problem. If you had electrical sensor trouble, the car would have noticed problems reconciling the transmission output speed with the four wheels' measured speeds from ABS and flagged it. You should probably be focusing on your wheels and tires.

The speedo will have been correctly calibrated as it left the factory: with the OEM wheels, with the OEM tires, and with OEM spec inflation. Any change here can affect accuracy. Not all tires and wheels of the same theoretical spec are exactly alike. Worn out tires will roll faster than new tires. Poorly inflated tires (temperatures are dropping!) will roll faster than properly inflated tires. Etc etc, and all sources of error are cumulative. It's not difficult to make a substantial difference. Spotting such differences is actually how indirect TPMS systems work. Some cars (I've personally witnessed this on a couple of Korean cars) are so picky they start having a bunch of false traction control and ABS engagements if you have a new tire and a worn tire on the same axle.

Jason
 
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   #11  

mtl

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Underlying that, the car still should have a pretty good idea of how fast it's going. It's been a very long time since I tried this, but I seem to recall both of my cars being pretty close to dead-on as compared to GPS.
Correct.
On My Octavia 2 I checked the actual speed of the car through hidden menu of Climatronic (https://www.youtube.com/watch?v=gIEEUNmR7J8&list=PLfbZtq6EMuERkgT6wnVEiyH_QYp8bLAGQ&index=17 , channel 19, subchannel 0 (for km/h) or subchannel 1 (for Mph)) and the difference to GPS was only 1 km/h at 100 km/h, while the speedo was showing 106 km/h. So the car actually knows the actual speed, but it shows higher speed as Jason already described.
Also this is very correct:
The speedo will have been correctly calibrated as it left the factory: with the OEM wheels, with the OEM tires, and with OEM spec inflation. Any change here can affect accuracy. Not all tires and wheels of the same theoretical spec are exactly alike. Worn out tires will roll faster than new tires. Poorly inflated tires (temperatures are dropping!) will roll faster than properly inflated tires. Etc etc, and all sources of error are cumulative. It's not difficult to make a substantial difference. Spotting such differences is actually how indirect TPMS systems work. Some cars (I've personally witnessed this on a couple of Korean cars) are so picky they start having a bunch of false traction control and ABS engagements if you have a new tire and a worn tire on the same axle.
Anyway, I don't have any experience with Jetta, but you should be able to get into hidden menu and then check for the actual speed. Maybe this will work (I suppose that your Jetta is based on Golf MK6, if it is still MK5, first video should work for you): https://www.youtube.com/watch?v=0JrYIvIljwo
 
   #12  

Spacewalker

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Take a VCDS, go to EGINE Measue Block ,and find a field with a Vechicle speed and compare this with your speedo.
Did DIGITAl speed and "needle speed" is this same ?
Also you can look in Cluster - Advanced Meas Block to check real wheel diameter.

WHo said that GPS speed is right ?

if you really want check car speed you should use tacho directly connect to the drive shaft
 
   #13  

In My Garage

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There's definitely a small, positive error designed into the analog needle display.

The speedo will have been correctly calibrated as it left the factory.

Jason
Jason, I come from a calibration world having run a standards lab and 8% is huge!!!

Plus that 8% was the same when the car was a month old.

Plus that same number is reported by other owners with the same model and series of car.
 
   #14  

In My Garage

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Who said that GPS speed is right?
Trust me, far more accurate than a speedo.

if you really want check car speed you should use tacho directly connect to the drive shaft
And then that system would need to be calibrated. People, reading a display, even a digital display, means nothing unless the system is calibrated.
 
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   #15  

mtl

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Take a VCDS, go to EGINE Measue Block ,and find a field with a Vechicle speed and compare this with your speedo.
Did DIGITAl speed and "needle speed" is this same ?
Also you can look in Cluster - Advanced Meas Block to check real wheel diameter.
Of course, you can check actual speed also through VCDS, I forgot to mention this, because I always check it through Climatronic, since it is much safer than driving with laptop on your knees. If you have another person than it is a different story.

WHo said that GPS speed is right ?
If you are driving on a a road without any descent/ascent and in straight line than I would say this is as correct as you can have it without any expensive measurement equipment.
Just for example: we have traffic signs that measure and show your speed and in 90% there is no difference to GPS speed and the rest the difference is 1km/h.
 
   #16  

In My Garage

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Of course, you can check actual speed also through VCDS.
There are only two speeds; "indicated" and "true" which we would hope are the same. But in many cases they are not. That is where calibration comes in, either in an adjustment or a calibration table.

The VCDS can only report a speed based on the math within the module that handles the speed display. This will be determined by the tire rotation versus distance, the number of pulses (ABS wheel sensor or drive shaft sensor) and the math (including time) that then converts to a digital display of MPH or KPH.
 
   #17  

In My Garage

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Ideally, I wish VW AG would just give me a window in the program where I enter a number so as to get the correct speed displayed.

Let us assume the ABS sensor ring has 72 teeth and that at 100 KPH, the wheel rotates 500 times per kilometer. That would be 36,000 pulses in 1 kilometer or in 36 seconds. Or 1000 pulses per second if the circuit is designed to update at that rate.

All I would need to do is divide by 10 to get 100 KPH.
 
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mtl

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That would be perfect, but I guess there would be some legal consequences to that.
This is also why speedos of all cars usually show cca. 5% more than the actual speed.
 
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Sebastian

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This should help you... :)

http://forums.tdiclub.com/showthread.php?p=3047646#post3047646

BTW: Don't calculate based on the analog gauges, if in doubt use the digital display as reference. The analog gauges are often enough not ideally calibrated (the motors that run them actually), so there may be some added inaccuracy. Also note that there are models which use secondary distance impulse number to calculate the distance travelled, so that may be off as well (meaning there may not be just 2 speeds you're looking at but 3)! In other words, double check not just the analog gauges but also the digital ones (and/or if not available the measuring values) as well as the displayed distance travelled. Test institutions use an external wheel with a defined circumference and calibrated speed sensors. They don't use any of the vehicle's own system, nor do they use GPS - yet for our use the GPS should be good enough. ;)
 
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