2008 Skyline 370GT - Speedo Re calibration?

[Vee37]

Has anyone re-calibrated their speedo?

I changed my tires (width & profile) and went down a bit in OD,which has really screwed the accuracy of my speedo.

I found the following product, which looks really interesting. https://yellr.com/ and here is a vid explaining how it works and is configured. 

I will send them an email asking its availability in AUS and if they have a dealer and if its compatible with a 2008 370GT; or at least a 2009 G37.

But if someone already has experience with it, that would be brilliant.

PS: I think my speedo is about 20% out!

[sonicii]

I thought any car built in the last 20 years or so would use wheel speed sensors (also used for ABS/TC) for the speedo, not a pick-up in the transmission.

[Vee37]

On 3/3/2022 at 7:41 PM, sonicii said:

I thought any car built in the last 20 years or so would use wheel speed sensors (also used for ABS/TC) for the speedo, not a pick-up in the transmission.

Its irrelevant where the rotation / angular velocity is measure from. It still uses the calculation of angular speed multiplied by diameter (ie 2 * ¶ *R) over time = speed. I am changing the diameter/radius without telling it, so it will assume the wrong diameter, and thus calculate the wrong speed. You have to have both angular rotation speed and diameter accuracy, to then calculate the correct speed.

On my previous 350GT, I started with 18" and went to very wide 19" (profile kicked up the OD, even though they were low)  and the speed actually became more accurate due to the lower angular velocity; still a little out, but better. Manufacturers have always underestimated the calculated speed, probably so no-one sues them because they unwittingly get speeding fines; they would of course claim safety.

[Ben C34]

Of course it matters where the calculation takes place.

 

What if it uses wheel speed sensors to calculate speed and then sends the speed signal to the dash via CAN communication? 

 

The speedo healers work  well when there is a suitable signal to intercept and adjust. Don't go blindly assuming you can always do that.

[Ben C34]

Anyway, go to jaycar and buy that. https://www.jaycar.com.au/speedo-corrector-module/p/AA0376

Less than the cost to ship something from america.

 

[Vee37]

On 3/3/2022 at 8:26 PM, Ben C34 said:

Anyway, go to jaycar and buy that. https://www.jaycar.com.au/speedo-corrector-module/p/AA0376

Less than the cost to ship something from america.

 

Thats perfect. Its basically like the other one, but cheaper to start with, and its in AUS!

I like the other ones under card / out of sight / water resistance abilities and possibly plug and play. This ones install sounds a little more complex. (from manual) But with JayCars return policy (7 days), its looking good. Thanks.

 

EDIT: Now that I added a search for "Speedo Correction Module" I actually found info on people who may install it, and forum posts of people who have installed it. But not on a V36.

Edited March 3, 2022 by Vee37

[sonicii]

Well, there are 4 wheel speed sensors, are you going to use 4 kits?  I can just imagine the chaos created with ABS/TC/VCD if you only modify the output of one or 2.

Also keep in mind the speed sensors give the ECU quite an accurate indication of speed, it is just the speedo needle the reads high, by offsetting any speed sensors to correct the speedo needle, your ECU will incorrectly read your speed which may have other consequences.

Edited March 4, 2022 by sonicii

[Vee37]

On 3/4/2022 at 6:29 PM, sonicii said:

Well, there are 4 wheel speed sensors, are you going to use 4 kits?  I can just imagine the chaos created with ABS/TC/VCD if you only modify the output of one or 2.

Also keep in mind the speed sensors give the ECU quite an accurate indication of speed, it is just the speedo needle the reads high, by offsetting any speed sensors to correct the speedo needle, your ECU will incorrectly read your speed which may have other consequences.

I am willing to bet that the individual speed sensors on each wheel are for the specific use by the traction control and not used for the speedometer. The car in the above linked video would also have traction control, and they only install a single unit. If it was otherwise, the manufacturer would also have the same issue, as well as mixing functional units, and mixing safety items with non-safety needs.

My understanding of what I have seen, is that the speedometer is simply a single rate counter of an electronic pulse. In the above example it runs off the final drive out the gearbox (like it always has before ECU's using a spinning cable). The number of pulses that occur over a given time period, gives angular /  rotation speed, and the speedo is simply scaling that number up/down by multiplying it by the wheels outside diameter, to give meters per second. The above module and the one I originally linked, simply send a slower / faster pulse by a multiplier (%), thus tricking the speedo into thinking its rotating at a different rate, and hence the car is travelling at a different speed. This would be similar as If i put 13" wheels with 30 series tires, or then changed them to 22" rims with 45 series tires. The actual physical speed is irrelevant, its simply a numerical calculation for visual representation ie the dash instrument facing the driver.

My plan is to go through the parts catalog to find where the sender unit is placed.

 

Checked the parts....

OK. Interesting, there is a sensor at the back of the gear box (similar to the example vid above) that is labeled "SENSOR ASSY-REVOLUTION". That sounds pretty much like what I was expecting, even before I checked for it.

https://partsouq.com/en/catalog/genuine/parts?c=Nissan&ssd=%24*KwE2AhN_bl93d0YzQHofHm56Wl1DMj0wMSMwJmBFeSFwJzgiHnFjJmhlYCY_WSIFYm0oJ1oxJikgWG5xEnl7d2pgRXkiMDorJj86NjEpIG06MG0-J1oxJikgdT5xdSYxMTBFJTIwb3EyenNrZ0R-IGkpcXUmQ1BCSUAgLH86PCY_IEBPUzE2aWN8NTA3ISgnZ2F_aRRZeAAAAAClhw-n%24&vid=0&gid=438&q=CKV36-403155

Edited March 4, 2022 by Vee37

[sonicii]

On 3/4/2022 at 7:19 PM, Vee37 said:

I am willing to bet that the individual speed sensors on each wheel are for the specific use by the traction control and not used for the speedometer.

Good luck then.. I installed one of these on my old 1993 J30 maxima which actually used the speedo cluster to process the speed sensor input before sending it to the ECU, that was the last car I owned that used a transmission output speed sensor for measuring vehicle speed.

I can tell you 100% my 6MT V35 has no speed sensor in the transmission, only a reverse switch and neutral switch.  So I am fairly certain the output speed sensor on the auto is for the TCU.

But let us know how you get on.

I have attached an image from the V35/G35 service manual which might be helpful..

[sonicii]

Also found this, which is from the factory service manual for your 2008 V36.

 

[Vee37]

On 3/4/2022 at 9:19 PM, sonicii said:

Good luck then.. I installed one of these on my old 1993 J30 maxima which actually used the speedo cluster to process the speed sensor input before sending it to the ECU, that was the last car I owned that used a transmission output speed sensor for measuring vehicle speed.

I can tell you 100% my 6MT V35 has no speed sensor in the transmission, only a reverse switch and neutral switch.  So I am fairly certain the output speed sensor on the auto is for the TCU.

But let us know how you get on.

I have attached an image from the V35/G35 service manual which might be helpful..

Yep, YOUR RIGHT, I was WRONG! I would loose that bet! luckily I'm not a betting man. I found the exact same diagram as below (ie similar to your V35) in the G37 manual I use.

On 3/5/2022 at 10:46 AM, sonicii said:

Also found this, which is from the factory service manual for your 2008 V36.

 

I use the 2009 G37 manual, and I also found a page or two later the following.

Which simply confirms that the communication to the speedo is using the CAM protocol, and not simply a pulse-frequency to transmit the speed, as I originally thought/hoped.

I am speaking with a guy here in Sydney that thinks he may be able to modify the computer to adjust the speed. But he sounded like he thought there would be a limited range of adjustment available. The other obstacle is that my current tyres are a temp situation. So I would need to adjust again when I change my wheels. I went low profile (30s) as I got cheap ones (just temporary until I upgraded wheels) I expected the cheap tyres to be of questionable grip/handling, but they got really good reviews on-line, and now that i have them, they are really hard to fault and are matching my previous (350GT with continentals being 3 times moire expensive) . I would buy again.

<start rant>Not to get all conspiracy theory on this, but the 10% under from factory on basically all cars, when multiplied out for the billions of cars doing hundreds of thousands of K's, the auto industry (inc oil change, services etc etc) are taking the cream. This would be costing the consumers billions of dollars. It also bothers me a little that until I change my wheels, my Odometer is going to be showing more K's<end rant>

Edited March 5, 2022 by Vee37

[sonicii]

On 3/5/2022 at 10:30 AM, Vee37 said:

Not to get all conspiracy theory on this, but the 10% under from factory on basically all cars, when multiplied out for the billions of cars doing hundreds of thousands of K's, the auto industry (inc oil change, services etc etc) are taking the cream. This would be costing the consumers billions of dollars. It also bothers me a little that until I change my wheels,

As I mentioned earlier, in most cases the car is measuring your speed quite accurately, if you can use consult or some other OBD2 tool to display speed, you will see it shows a figure lower than your speedo is showing, meaning your odo and trip meters are usually correct (assuming you use factory size tyres, or at least the same diameter as factory tyres), so no global conspiracy to make you spend more on servicing.  It is just the speedo needle that reads high as ADRs require the speedo to read you actual speed or up to 10% above, but never below, to prevent the chance of the speedo ever reading below actual speed and therefore being in breach of ADRs, most manufacturers set the speedo needle to read 5-7% high

[Duncan]

When I first need to buy tyres for a new car, I just put the correct size on to get an accurate speedo. It generally is a fair bit taller than factory which also helps with ride quality and ground clearance.

I used one of those jaycar adjusters on the stagea for a while, but ultimately getting correcting it with tyre size is simple and reliable

[The Bogan]

Have you checked your dash vs GPS

The up to -10% thing is a factor for error that the manufacturer factors in

They are not allowed to have a speedo reading of 100 kph, but actual speed of 101 kph

So the error is -0% + 10% I believe

I believe this takes into consideration variations of tyre sizes with different models, and tyre wear

[Vee37]

On 3/5/2022 at 12:36 PM, sonicii said:

As I mentioned earlier, in most cases the car is measuring your speed quite accurately, if you can use consult or some other OBD2 tool to display speed, you will see it shows a figure lower than your speedo is showing, meaning your odo and trip meters are usually correct (assuming you use factory size tyres, or at least the same diameter as factory tyres), so no global conspiracy to make you spend more on servicing.  It is just the speedo needle that reads high as ADRs require the speedo to read you actual speed or up to 10% above, but never below, to prevent the chance of the speedo ever reading below actual speed and therefore being in breach of ADRs, most manufacturers set the speedo needle to read 5-7% high

Thats another issue I am having. I cant seem to connect ,my Bluetooth ODBII scanned to my phone.I have a cheap ebay one I have been using previously on my 350GT for years without any issue, but now, it doesnt connect to my 370GT, having an "init failure". I have also purchased the one from JayCar, and that has the  same issue.

I used to use Nissan DataScan as at the time I started, tourque couldnt connect to the Japanese protocol.

Is there a trick to it? It just worked on the 350GT.

As for accuracy internally, it will still be out if you change the rolling diameter (ie wheel diameter, profile / width) as the ECU does not know of the change to the wheels.

On 3/5/2022 at 1:29 PM, mlr said:

Have you checked your dash vs GPS

The up to -10% thing is a factor for error that the manufacturer factors in

They are not allowed to have a speedo reading of 100 kph, but actual speed of 101 kph

So the error is -0% + 10% I believe

I believe this takes into consideration variations of tyre sizes with different models, and tyre wear

Checking my GPS to my speedo is EXACTLY how I know my speedo is out. Normally its around 10% out, but I have got lower profile tires (vs width) that has lowered my rolling circumference, so now my speed is even more out of step with the GPS speed. 

On my previous 350GT I went from 18's to 19's, and the speed displayed closer to real speeds.

Edited March 5, 2022 by Vee37

[sonicii]

On 3/5/2022 at 4:37 PM, Vee37 said:

I used to use Nissan DataScan as at the time I started, tourque couldnt connect to the Japanese protocol.

Is there a trick to it? It just worked on the 350GT.

If you are familiar with the NDS software, you can use the NDSIII version for the V36 -

https://www.nisscan.com/NDSIII/index.php

They also list suitable adaptors, which are different to those used on the V35.  I have one that seems to work ok on my Q50, even though it isn't listed as a compatible vehicle.

[Vee37]

On 3/5/2022 at 10:17 PM, sonicii said:

If you are familiar with the NDS software, you can use the NDSIII version for the V36 -

https://www.nisscan.com/NDSIII/index.php

They also list suitable adaptors, which are different to those used on the V35.  I have one that seems to work ok on my Q50, even though it isn't listed as a compatible vehicle.

THANK-YOU! i would of never of thought to have looked for the next version of NDS! Eventually I probably would of emailed them directly, but who knows when I would come around to that obvious step.

I wont get a chance to test till later today, but I can hardly wait. My only "problem" is that I now have 2 ODBII - Bluetooth adapters now(cheap eBay one and a JayCar one). It will be a little interesting to see which version they each report for ELM and if one is more responsive than the other. My original cheap eBay one was a litty laggy; I assumed it was using a very old Bluetooth standard.

EDIT: Least of which will be to check my ECM against the speedo 

Edited March 5, 2022 by Vee37

[Vee37]

Yep. Nissan Datascan III works.

I tried both my Bluetooth Do0ngl;es, and  was a little suprised they reported the exact same version number. My old cheapie dongle is about 7 years old now, and the JayCar one is brand new.