Speedometer Over Reading.

[PAJ32]

Hey guys, I have an absolutely stock 2010 NT Platinum diesel auto 5 door,

From the first time I drove it I thought that the speedo was reading fast so I have checked it against 2 different GPS units & it is reading a constant 10% over......

IE: When it is reading 110kmh the car is doing 100kmh. & when reading 66kmh it is actually doing 60kmh. etc.....

(Has stock, factory alloy wheels with 265/65/17 Bridgestone A/T Duelers.)


Any ideas / reasons why it should be reading incorrectly & any easy way of fixing? Thanks.

[Dicko1]

By law all speedos must read over. My NW (2014) shows 100kph on speedo but in actual fact it is doing 95kph based on the 2 GPS units I have in the car. Some people have put larger diameter tyres on and this has corrected the speedo but really not needed. This is why sometimes when travelling on a highway you will follow a car sitting on 95kph gps speed but his speedo is showing 100kph and he thinks they are sitting on the speed limit...can be frustrating..especially for truck drivers whose job revolves around deadlines.

[PAJ32]

Yeah Dicko I know they are supposed to read a little over but this is a full pita. (up to 5% would be okay in my opinion but 10% is crazy!)

It will also have trip computer, fuel economy readings out & it is clocking up 10% extra milage on the odometer as well.



Yeah, on highway the speedo was showing 110 & I was holding up traffic.

I have been around the trade since 1974 & have a good gut feel for what speed I am doing but nevertheless I want to try & sort it.

[Kingmarz]

33’s make the speedo perfect

[Toshmegosh]

Yeah Dicko I know they are supposed to read a little over but this is a full pita. (up to 5% would be okay in my opinion but 10% is crazy!)

It will also have trip computer, fuel economy readings out & it is clocking up 10% extra milage on the odometer as well.



Yeah, on highway the speedo was showing 110 & I was holding up traffic.

I have been around the trade since 1974 & have a good gut feel for what speed I am doing but nevertheless I want to try & sort it.

Interesting, I had never thought about the odometer impact, mine is 5% over. In "the good old days" it would have been justification (moral, not legal) for a rewind, I guess we are stuck with it these days.

[PAJ32]

33’s make the speedo perfect

lol.... Thanks, just bought brand new stockies,



besides, mine is just a tarmac princess.

[rgrubby]

Yeah Dicko I know they are supposed to read a little over but this is a full pita. (up to 5% would be okay in my opinion but 10% is crazy!)

It will also have trip computer, fuel economy readings out & it is clocking up 10% extra milage on the odometer as well.



Yeah, on highway the speedo was showing 110 & I was holding up traffic.

I have been around the trade since 1974 & have a good gut feel for what speed I am doing but nevertheless I want to try & sort it.

My NS was close to that far out with standard tyres.
I believe the speedo display is incorrect independently of the rest of the system. I have a vague memory of seeing two speeds in my iCarsoft OBDII reader, plus the ABS wheel speeds.

[spot01]

I've had 6 Gen 4 Pajeros and they have all read fast by at least 5%, with some perhaps 8%, so this is normal.

I don't even look at the speedo. I run a Garmin GPS in the right hand lower corner of the windscreen, as it is much easier to see & is accurate. It also beeps if I exceed the speed limit.

You could try an Auto Instrument specialist to see if they can recalibrate it, but a GPS is probably cheaper & better.

[Dicko1]

I've had 6 Gen 4 Pajeros and they have all read fast by at least 5%, with some perhaps 8%, so this is normal.

I don't even look at the speedo. I run a Garmin GPS in the right hand lower corner of the windscreen, as it is much easier to see & is accurate. It also beeps if I exceed the speed limit.

You could try an Auto Instrument specialist to see if they can recalibrate it, but a GPS is probably cheaper & better.

Likewise...I drive to the speed reading from the Ultragauge.

[PAJ32]

I've had 6 Gen 4 Pajeros and they have all read fast by at least 5%, with some perhaps 8%, so this is normal.

I don't even look at the speedo. I run a Garmin GPS in the right hand lower corner of the windscreen, as it is much easier to see & is accurate. It also beeps if I exceed the speed limit.

You could try an Auto Instrument specialist to see if they can recalibrate it, but a GPS is probably cheaper & better.

I have 2 portable GPS units, one is now permanently in the car, just looking for a fix for the speedo if possible.

I would also like to be able to rely on the trip computer for things like accurately monitoring fuel consumption etc.

[redbruce]

I have an MY15 NX and run an Ultraguage for my digital speedo.

1. Digital speed and analogue speed readouts are not the same. Analogue reads higher.

2. With 265/65r18 Falken AT3W (31.7" ie 4% larger than stock) my digital speedo reads 0.5% high, my analogue (OEM) speedo reads 3% high and my odo reads spot on. Factory fuel consumption (auto mode) on trip meter reads 0.5% low. All based on 3 x GPS units and actual measurement against kilometer posts (over 600km) and fill/km travelled.

So OEM speedo on factory tyres read 7% high, odo read 4% high, fuel consumption was 3.5% low on stock tyres.

ADR's require factory speedo to always read higher than actual.
Relevant ADR is ADR 18/03 (https://www.legislation.gov.au/Series/F2006L01392)

I have an ARB Frontier long range tank and have calibrated my Ultraguage to give me accurate consumption, distance to empty, etc. I also use it to monitor powertrain, engine, intake, and auto trans temps, boost and rpm as I find the OEM dask binacle hard to see in sunglasses..

[Gravel Seeker]

Yeah Dicko I know they are supposed to read a little over but this is a full pita. (up to 5% would be okay in my opinion but 10% is crazy!)
It will also have trip computer, fuel economy readings out & it is clocking up 10% extra milage on the odometer as well.
Yeah, on highway the speedo was showing 110 & I was holding up traffic.
I have been around the trade since 1974 & have a good gut feel for what speed I am doing but nevertheless I want to try & sort it.

The speedo is over to prevent people from speeding. I would assume they just take the odo signal and add a percentage for the speedo.
The odo should be accurate though. For a number of reasons;

1. Service and warranty
2. Insurance. Don't know about Oz, but here we have a certain distance we can use the vehicle every year depending on what you pay for.
3. Safety - if the odometer is not accurate we run the risk of people dying between fuel stops, because the gauge show different actual range than the road sign show distance to fuel.
4. Consumption figures
5. Re-sale value

My NW came with 265/60-18, but I am now running 265/70-17 (Nokian Rotiiva AT plus) and the speedo is bang on with the GPS. Exact same number. Used to be ca 5% out.

[redbruce]

The speedo is over to prevent people from speeding. I would assume they just take the odo signal and add a percentage for the speedo.
The odo should be accurate though. For a number of reasons;

1. Service and warranty
2. Insurance. Don't know about Oz, but here we have a certain distance we can use the vehicle every year depending on what you pay for.
3. Safety - if the odometer is not accurate we run the risk of people dying between fuel stops, because the gauge show different actual range than the road sign show distance to fuel.
4. Consumption figures
5. Re-sale value

My NW came with 265/60-18, but I am now running 265/70-17 (Nokian Rotiiva AT plus) and the speedo is bang on with the GPS. Exact same number. Used to be ca 5% out.

Have you checked odo accuracy yet?

[PAJ32]

Have you checked odo accuracy yet?

Not at this stage but when I get the chance to go for a few hundred km drive I will take a look.

[grumpmeister]

My speeds are based on the Ultraguage that way I know without doubt that I am not speeding

At 50 on the dash I am doing roughly 49 on the Ultraguage
At 100 on the dash I am doing 103 on the Ultraguage
At 110 on the dash I am doing closer to 120 on the ultraguage

These speeds didn't vary more then a fraction with the new tyres 265/65/18's

As for the law I've never heard of the law stating speedo must read over, but then again like most things it's open to interpretation. ADR's make no mention of it either aside from providing a range the speedo must fall within.

https://www.parliament.vic.gov.au/im...5_McDonald.pdf
http://trafficlaw.com.au/speedos.html
https://www.news.com.au/technology/m...b281d65ecd37f0