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Hi!

Iv got problem with my 2003 Celsior. At 60 mph on speedometer I get 40 mph on GPS. Car is on 20 inch wheels but the difference between readings is too big in my opinion to be caused only by the wheel diameter. Where to look for the problem? Speed sensor, speedometer it self? Car is Japanese import. Readings of speed are very smooth without any pikes or something, just the value is way off the real one.

Thanks, Jan. 

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Because it's a Jap import the speedo will be calibrated in kilometres per hour rather than MPH.

60kph = 37.282mph

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12 hours ago, aLLypl said:

Hi!

Iv got problem with my 2003 Celsior. At 60 mph on speedometer I get 40 mph on GPS. Car is on 20 inch wheels but the difference between readings is too big in my opinion to be caused only by the wheel diameter. Where to look for the problem? Speed sensor, speedometer it self? Car is Japanese import. Readings of speed are very smooth without any pikes or something, just the value is way off the real one.

Thanks, Jan. 

How long have you had the car and has it always been that way in your ownership?

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2 hours ago, The-Acre said:

How long have you had the car and has it always been that way in your ownership?

Im owner since one month, its been like this when i bought it

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5 hours ago, Herbie said:

Because it's a Jap import the speedo will be calibrated in kilometres per hour rather than MPH.

60kph = 37.282mph

Your right but my speedo is in km h and mph and both readings are wrong

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My LS400 Mk4 shows the speedo doing 70mph but the Satnav which is digital and far more accurate

shows we are only doing 65mph.

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All speedometers over-read by anything up to 10%

Regulations demand they never under-read, so manufacturers set them 'high'

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32 minutes ago, aLLypl said:

Your right but my speedo is in km h and mph and both readings are wrong

The satnav will always be more accurate and should read lower than the speedo. Have a read of this article to understand why:

https://www.thecarexpert.co.uk/how-accurate-is-a-car-speedometer/

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But my differnece is up to 20 mph!! Whats interesting if i set gps to kmh, readins in mph on speedometer are quite accurate so wtf is it all about ? 😮

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Whats more interesting, distance meter works fine, so ivgot right readings for kmh on mph display... Thats weird.. Any ideas ? 

6 hours ago, Herbie said:

Because it's a Jap import the speedo will be calibrated in kilometres per hour rather than MPH.

60kph = 37.282mph

Your right but my speedo is in km h and mph and both readings are wrong

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2 hours ago, NemesisUK said:

All speedometers over-read by anything up to 10%

Regulations demand they never under-read, so manufacturers set them 'high'

Quite right.

My Merc has overead by 8% for the last 17 years!

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Sounds to me like someone fitted a Speedo converter when it wasn't necessary. If your speedo reads both Mph and Kph then a converter is not needed for the UK. If it reads only Kph then you can either fit a speedo converter which means 70Kph shown on the speedo is now 70Mph or else fit a sticker to the dial that converts it for you. Either way, whoever imported it did a very poor job. If you bought it from the importer, give them a call and tell them what you've seen. It sounds to me like they fitted an Mph to Kph converter rather than a Kph to Mph.

The speedo receives an input from the sensor (some use gearbox, some use ABS wheel sensors) and converts it to the speed display. The converter changes the frequency of the input so that the speedo displays the correct value.

However, if the difference in the rolling radius of your 20" wheels and tyres is substantially different from the standard wheels then that could be enough to throw out an already inaccurate speedo. My LS430 shows 78Mph on the Speedo at a GPS speed of 70Mph.

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7 hours ago, BigBoomer said:

Sounds to me like someone fitted a Speedo converter when it wasn't necessary. If your speedo reads both Mph and Kph then a converter is not needed for the UK. If it reads only Kph then you can either fit a speedo converter which means 70Kph shown on the speedo is now 70Mph or else fit a sticker to the dial that converts it for you. Either way, whoever imported it did a very poor job. If you bought it from the importer, give them a call and tell them what you've seen. It sounds to me like they fitted an Mph to Kph converter rather than a Kph to Mph.

The speedo receives an input from the sensor (some use gearbox, some use ABS wheel sensors) and converts it to the speed display. The converter changes the frequency of the input so that the speedo displays the correct value.

However, if the difference in the rolling radius of your 20" wheels and tyres is substantially different from the standard wheels then that could be enough to throw out an already inaccurate speedo. My LS430 shows 78Mph on the Speedo at a GPS speed of 70Mph.

My speedo is mph and kph, mpg reading shows kph speed. Where can i look if the converter was fitted and how it looks?

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My Celsior had the instrument cluster replaced for a UK one, maybe you could consider doing the same?  Get hold of Paul Frost at Lexussparesdirect (via eBay) and ask him for a price. He may even tell you how to change the mileage on it.

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Ov got original from jap spec and would like to keep it... As it shows both mph and kph. No others ideas what can be wrong ?

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On 6/4/2019 at 2:04 PM, aLLypl said:

Your right but my speedo is in km h and mph and both readings are wrong

Any chance of a picture?

Do you mean that the dial has two circles of numbers - one for kph and the other for mph? 

If that's the case, does this mean that when the pointer is indicating 60 mph, it's also indicating 97 kph?

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26 minutes ago, Thackeray said:

Any chance of a picture?

Do you mean that the dial has two circles of numbers - one for kph and the other for mph? 

If that's the case, does this mean that when the pointer is indicating 60 mph, it's also indicating 97 kph?

Excally !  And 60 mph on speedo is around 60 kmh on gps .

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haven't we all got that same speedo style ?

I think I've had it on all my 3 Ls400s from my first 1992 car

Malc

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2 hours ago, aLLypl said:

IMAG1554.jpg

The odometer in the picture is showing kilometres. Is it possible to change this to miles in the settings?

 

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Not sure if it can be changed electronically in the settings options but even if the speedometer scale displays both MPH and KPH if the speed matches your sat nav when in KPH mode the speedometer is still reading KPH and has not been converted to MPH. Mine was already converted when I bought it and was simply done by a retrofit module wired in behind the dash.

The larger 20” wheels are also going to add to the error.

I would also imagine the only FM radio station you receive is Radio 2 as the Japanese radio band is also different to the UK one.

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1 hour ago, steve2006 said:

Not sure if it can be changed electronically in the settings options but even if the speedometer scale displays both MPH and KPH if the speed matches your sat nav when in KPH mode the speedometer is still reading KPH and has not been converted to MPH. Mine was already converted when I bought it and was simply done by a retrofit module wired in behind the dash.

The larger 20” wheels are also going to add to the error.

I would also imagine the only FM radio station you receive is Radio 2 as the Japanese radio band is also different to the UK one.

I only get radio 2 and one other rubbish one, but interestingly driving through Germany I got loads in German and French.

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15 hours ago, steve2006 said:

Not sure if it can be changed electronically in the settings options but even if the speedometer scale displays both MPH and KPH if the speed matches your sat nav when in KPH mode the speedometer is still reading KPH and has not been converted to MPH. Mine was already converted when I bought it and was simply done by a retrofit module wired in behind the dash.

The larger 20” wheels are also going to add to the error.

I would also imagine the only FM radio station you receive is Radio 2 as the Japanese radio band is also different to the UK one.

Your 100% right. Can you recommend me someone who can help mi with both things ? Im in Bedford.

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