jkirkebo
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Leaf Number: 007344
Location: Fredrikstad, Norway

Speedometer calibration ?

Sun Feb 26, 2012 3:58 am

My speedo reads 8% high. Avg.speed is correct as is driven distance. Does anybody know if it is possible to calibrate the speedometer by using the Consult-thing at the dealer ? I would really like a 100% correct speedometer...

Smidge204
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Re: Speedometer calibration ?

Sun Feb 26, 2012 7:08 am

8% is within the federally mandated error range of +/-10% - probably won't be a warranty item if they bother to fix it at all. I'd learn to live with it since it's basically erroring in your favor anyway. I'm also curious as to how you verified the error margin...

You will usually find that speedometers read high since nobody wants a lawsuit over a speeding ticket. "But officer, my speedometer said I was going 55, not 60!"
=Smidge=

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garygid
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Re: Speedometer calibration ?

Sun Feb 26, 2012 7:44 am

I think +/- 10% is incorrect.
Where did you get that, or is it a guess?

I think the law requires the speedometer to NOT read low (in OEM configuration, tire pressure, etc.), so the DISPLAYED speed is usually about 2% over the internally "calculated" speed.

If you are 8% high, that wiuld seem unusual, and your tire pressure and temperature might be low?

Using the hidden "Calibration" screens (with Audio power off, quickly press: Map, Map, Map, Audio (on), Audio (off), Map).

One of the screens shows the "wheel" and GPS derived speeds (100.0 kph (shown as 1000) = 62.5 mph) and the LEAF will "usually" DISPLAY about 65 mph in the dash "eyebrow".

It might also indicate if the wheel (or motor RPM) derived speed differs from the GPS derived speed.

I am not aware of any way to change the Speedometer "offset", or recalibrate the internal speed. Since the LEAF has the GPS-derived speed available, it COULD be self-calibrating, and carefully reporting 2% high. But, if your car is actually showing 8% high, then it would appear that your car is NOT self-calibrating.

Of course, running larger diameter rims or higher-profile tires would make your car go faster than indicated by the RPM-derived speed.
Last edited by garygid on Sun Feb 26, 2012 7:53 am, edited 1 time in total.
See SOC/GID-Meter and CAN-Do Info
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turbo2ltr
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Re: Speedometer calibration ?

Sun Feb 26, 2012 7:46 am

It would seem very unusual for the speed to be high and the distance to be correct. They are usually derived from the same signal.
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garygid
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Re: Speedometer calibration ?

Sun Feb 26, 2012 7:55 am

The DISPLAYED speed is deliberately shown higher than the internally-used speed.
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
To Sell: X-treme 5000Li EV motorcycle

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turbo2ltr
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Re: Speedometer calibration ?

Sun Feb 26, 2012 7:59 am

garygid wrote:The DISPLAYED speed is deliberately shown higher than the internally-used speed.


I assume you are speculating and haven't reverse engineered the firmware in the dash display?

I've never worked with an ECU that has held two different speeds. That's not to say it's not possible, but I haven't seen it. The Speed in the ECU is always the speed that is displayed.
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jkirkebo
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Location: Fredrikstad, Norway

Re: Speedometer calibration ?

Sun Feb 26, 2012 8:31 am

turbo2ltr wrote:
garygid wrote:The DISPLAYED speed is deliberately shown higher than the internally-used speed.


I assume you are speculating and haven't reverse engineered the firmware in the dash display?

I've never worked with an ECU that has held two different speeds. That's not to say it's not possible, but I haven't seen it. The Speed in the ECU is always the speed that is displayed.


My average speed and distance reads correct. If I accelerate to 80kph, set the cruise control and reset the avg. speed, it will show ~75kph after a while. I have to set the cruise control to 86kph for the average speed to read 80kph.

I have verified that the average speed is the correct one, by external GPS and radar speed displays along the road.

My tire size is the original one. The car seems to know the correct speed but still displays 8% high.

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garygid
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Re: Speedometer calibration ?

Sun Feb 26, 2012 8:40 am

In the LEAF, I have checked the display against the "calibration" screen.

The odometer is required to be "correct", so a "correct" internal speed can usually be derived. However, if a car is not making any "efficiency" calculations, a "real" speed might not be required internally.

I do not know if the "speed" is required for smog checking. Perhaps just the RPM is required?

However, since the speedometer is required to be "not low", it is standard practice (required in many countries) for the speedometer to display a higher value.

For example: The ScanGaugeII for the 2010 Prius shows the "real" (internal) speed, but the car's speedo displays a higher value.

In the LEAF's OBD data, I see what appears to be RPM, but I have not yet found distance or an explicit "speed" (that I could recognize).

Have you found tire pressure or battery pack temperature in the OBD data?
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
To Sell: X-treme 5000Li EV motorcycle


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garygid
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Joined: Wed Apr 21, 2010 8:10 am
Delivery Date: 29 Mar 2011
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Re: Speedometer calibration ?

Sun Feb 26, 2012 9:03 am

The rules for cars are different, I believe.
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
To Sell: X-treme 5000Li EV motorcycle

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