Digital speed display

[vprelovac]

Has anyone tinkered with idea of displaying the speed information that is coming from the ECU in some sort of digital display? Since this information is rougly 10% off the analog speedo instrument I guess it could be valuable to know. Any thoughts on this?

[Markarina]

I think most UK drivers use a Road angel, digital speed display and speed camera warning in one.

The alternative is to plug into the OBD port and monitor the data that way (mode 1 or mode 22)

[vprelovac]

OBD idea is nice one, but I think it could work only on ABY models?

Is there some schematics for getting digital speed output of the ECU?

[Billman]

On the S2 and RS2 with Autoclimate you can display the ECU speed in the Climate Display. It is channel number 17.

[vprelovac]

Billman, that sounds interesting. Can you elaborate your idea a littlebit? What one has to do?

[Billman]

It is integrated from the Factory.

You must press the Air recirculate button and the Arrow UP at the same time and then the Climate Display shows you something. Then with the + and - you can change the channels. Channel 17 is speed. when you go to 17 then press the Air recirculation button again.

[Keeper of The Kitten]

Hang on a minute - are we saying that the ECU displays real speed and the speedo has been set to display an over reading? I understood that this happened on most production cars anyway, but this is most intriguing! I don't have the facility myself but I am interested to know what goes on here...

__MDC__

[Billman]

I mean that without any modification you can display on the Autoclimate control display the ECU reading for speed.

[Keeper of The Kitten]

But does that reading differ from the speedometer reading, i.e. is it more accurate?

__MDC__

[Markarina]

Yes - basically any cluster that receives an electronic speed signal has a calibratable offset so that the indicated speed always reads higher than actual speed. We were specifically instructed that this parameter had to be in place by the OEM concerned, and it was a very prestigious OEM

[HPmuirt]

Another way to test it is drive at dead on 60 on your speedo and then reset your average speed on the computer. It will start calculating the new average and if you hold 60, you will find your average is around 57 or even less.

Cheers n

Si

[~Delta]

Works on A4 / A6 / A8 etc. But how do you get the screen to display miles? It obviously reads in km/h, is there a seperate channel?

[vprelovac]

Woo hoo climate control rules! This is most intriguing info, I am going to try it tomorrow.

Anyone has a list of displayable channels?

I was using average speed method today to confim that there is indeed around 9% difference in digital data (from ECU) and analog on speedo. 100 km/h indicated by speedo turned out to be only 91 km/h. 220 km/h was indeed only 200 km/h. That also brings one question if audi quted max speed of 247 km/h is that real or a "fake" one?

Is there some way to tune the analog display to show real data?

[Markarina]

I suspect that the channel displayed on the climate control is a standard OBD channel, and that a list of channels can be found in the OBD spec (look under mode 1), I'll try and dig it out at work tomorrow I suspect that channel 18 may well be speed in MPH

[fivepotnoodle]

Can't for the life of me remember where I picked this up, but remember saving it.

Press and hold the recirculation button. Then press the manual flow control up arrow. You should see a 1c. Press the temperature up ("+") or down ("-") buttons to select a code number. Then press the recirculation button again. The value should display. Press the temperature up or down button again to display another code.

Code Displayed Value
1 System malfunction - displayed as a Diagnostic Trouble Code (DTC), see chart below
2 Digital value of Interior Temperature Sensor, in Headliner (G 86)
3 Digital value of Interior Temperature Sensor, in Instrument Panel (G 56)
4 Digital value of Fresh Air Intake Duct Temperature Sensor (G 89)
5 Digital value of Outside Air (Ambient) Temperature Sensor (G 17), front
6 Digital value of Outside Air (Ambient) Temperature Sensor
7 Digital value of Ambient Temperature Sensor At Fresh Air Blower (G 109)
8 Digital value of Temperature Regulator Flap Motor Potentiometer (G 92)
9 Delta value of Temperature Regulator Flap
10 Non-corrected specified value of Temperature Regulator Flap
11 Digital value of Central Flap Motor Potentiometer (G 112)
12 Specified value of Central Flap
13 Digital value of Footwell/Defroster Flap Motor Potentiometer (G 114)
14 Specified value of Footwell/Defroster Flap
15 Digital value of Air Flow Flap Motor Potentiometer (G 113)
16 Specified value of Air Flow Flap
17 Vehicle Speed (km/h)
18 Actual Air Blower voltage (Volts)
19 Specified Fresh Air Blower voltage (Volts)
20 A/C Compressor (A/C Clutch) voltage (Volts)
21 Number of low voltage occurrences, non-transient
22 Cycle condition of A/C Refrigerant High Pressure Switch (F 118)
23 Cyclings of the A/C Refrigerant High Pressure Switch (F 118)
24 Cyclings of the switches, absolute non-fluctuating
25 Analog/Digital value, Kick-Down Switch
26 Analog/Digital value, Engine Coolant Temperature (ECT) Warning Light
27 Coding value
28 Engine Speed (RPM)
29 A/C Compressor speed in rpm (Equals Engine Speed x 1.2Cool
30 Software version
31 Display check (all segments of A/C Control Head display light up)
32 Potentiometer malfunction counter, Temperature Regulator Flap
33 Potentiometer malfunction counter, Central Flap
34 Potentiometer malfunction counter, Footwell/Defroster Flap
35 Potentiometer malfunction counter, Air Flow Map
36 Feedback value, cold end-stop, Temperature Regulator Flap Motor Potentiometer (G 92)
37 Feedback value, hot end-stop, Temperature Regulator Flap Motor Potentiometer (G 92), max. stop
38 Feedback value, cold end-stop, Central Flap Motor Potentiometer (G 112)
39 Feedback value, hot end-stop, Central Flap Motor Potentiometer (G 112)
40 Feedback value, cold end-stop, Footwell/Defroster Flap Motor Potentiometer (G114)
41 Feedback value, hot end-stop, Footwell/Defroster Flap Motor Potentiometer (G114)
42 Feedback value, cold end-stop, Air Flow Map Motor Potentiometer (G 113)
43 Feedback value, hot end-stop, Air Flow Map Motor Potentiometer (G 113)
44 Vehicle operation cycle counter
45 Calculated interior temperature (internal software, in digits)
46 Outside (ambient) temperature, filtered, for regulation (internal software)
47 Outside (ambient) temperature, unfiltered, (internal software, in deg C)
48 Outside (ambient) temperature, unfiltered, (in digits)
49 Malfunction counter for speedometer (vehicle speed) signal
50 Standing time (in minutes)
51 Engine Coolant Temperature (ECT) in deg C
52 Graphics channel 1 - A/C compressor switch-off conditions are identified by illuminated segments of the "88.8" display. See chart below.
53 Graphics channel 2 - Climate system electrical outputs are identified by illuminated segments of the "88.8" display. See chart below.
54 Control characteristics
55 Outside (ambient) temperature, in deg C or deg F depending on setting on A/C control head
56 Temperature in deg C, from Interior Temperature Sensor, in Headliner (G 86)
57 Temperature in deg C, from Interior Temperature Sensor, in Instrument Panel (G 56)
58 Temperature in deg C, from Fresh Air Intake Duct Temperature Sensor (G 89)
59 Temperature in deg C, from Outside Air (Ambient) Temperature Sensor (G 17), front
60 Temperature in deg C, from Ambient Temperature Sensor At Fresh Air Blower (G 109)
61 Software version (latest)

When you have finished viewing whatever code you need, just press 'Auto'/'economy' to go back to normal climate control mode....