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Speedo Calibration

chook

By chook,
in Four Door Family & Wagoneers

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Sydneykid Grand Master

Sydneykid

Posted
Posted
Has anyone attempted to adjust their Series 2 electronic speedo ? mines about 10% out.

Is it adjusted through a trimpot in the instrument cluster or by changing the pinion gear in the sender ?

Why is it 10% out? Have you changed the tyre diameter?

D Cheers :P

  • 1 year later...
DaveB Mentor

DaveB

Posted
Posted

Just for prosperity's sake... my S2 is exactly 10% out too; reads 10km/h above what I'm doing (verified by GPS etc) at 60 and above. I have the standard tyre profile of 205/55/16 and brand new tyres. I'm going to fit the Jaycar speedo corrector kit - thanks for the verification that it works on S2 Chook! Which wire is it??? I would like to trace it without removing dash if at all possible...

chook Mentor

chook

Posted
  • Author
Posted
Just for prosperity's sake... my S2 is exactly 10% out too; reads 10km/h above what I'm doing (verified by GPS etc) at 60 and above. I have the standard tyre profile of 205/55/16 and brand new tyres. I'm going to fit the Jaycar speedo corrector kit - thanks for the verification that it works on S2 Chook! Which wire is it??? I would like to trace it without removing dash if at all possible...

i didnt have any trouble finding it, perhaps it is written on the back of the instrument cluster i think, and you can trace it to the plug and harness from there. If you still cant find it, send me a PM and ill pull cluster out and let you know.

Jaycar was bit confusing to set up, but havnt had to worry about it since, works great.

DaveB Mentor

DaveB

Posted
Posted (edited)
i think it is variable in 1% increments

Correct! Got mine today; two adjustments which can be used simultaneously, one varies by 1% per step, the other by 10% per step. I say 'varies' because it can be set to alter the speed UP or DOWN (ie. faster or slower). I agree with you Chook there are heaps of options...

I'll try to take some pics as I proceed. What I would like to do though, is install this in the passenger side kick panel, where I can splice it right into the correct wire near the ECU, rather than pull my dash apart and try to fit it in there. Can anybody think of any problems with this approach?

I have been looking at the pinouts of the R34 ECU (found here: R34 ECU pinouts) though and I can't seem to find a speedo output? Only "Vehicle speed sensor signal (Vehicle speed sensor 2) - pin 29" plus there is a "Output shaft rotation sensor signal (Vehicle speed sensor 1) - pin 58" however that is just for automatics (which mine is) and both those pins appear to be inputs, not the ECU output to the speedo?

Chook can you remember the colour code of the wire you had to interrupt to install your kit? I might be able to trace it at the back of the ECU and save some other people some dash-removing hassles...

Edited by DaveB
chook Mentor

chook

Posted
  • Author
Posted

1 Problem: I think the speed sensor goes to dash first, then from dash to ecu, (or perhaps 2 independant wires) so either way, you would have to intercept before dash to change your speedo, at ECU will not change speedo.

Ill check dash wire soon

danwatt Collaborator

danwatt

Posted
Posted
OK, 30min later, SPEED SIGNAL is BLACK with WHITE stripe, goes into the single row plug above the temp gauge on back of cluster. Just intercept it about 15cm back from cluster.

I checked some information about the V35/M35 speed signal and the signal is transmitted form the VDC/TCS/ABS control unit and received by the Combination meters and then re-transmitted by the Combination Meters (Dash Cluster) to the ECM (Engine Control) and the TCM (Transmission control) as well as the BCM (Body control). IF you were to correct the signal for the speedo you would have to do it before the speedo but who know how this will affect the operation of the ECM & TCM with a modified signal.

I dont know why the speed signal is out it doesnt make sense. Probably the easiest way to correct the signal is with larger diameter wheels (~3% greater diameter)

I can confirm the the M35 has the same problem.

DaveB Mentor

DaveB

Posted
Posted
OK, 30min later, SPEED SIGNAL is BLACK with WHITE stripe, goes into the single row plug above the temp gauge on back of cluster. Just intercept it about 15cm back from cluster.

Thanks Chook that's quick work! :laugh:

I checked some information about the V35/M35 speed signal and the signal is transmitted form the VDC/TCS/ABS control unit and received by the Combination meters and then re-transmitted by the Combination Meters (Dash Cluster) to the ECM (Engine Control) and the TCM (Transmission control) as well as the BCM (Body control). IF you were to correct the signal for the speedo you would have to do it before the speedo but who know how this will affect the operation of the ECM & TCM with a modified signal.

I dont know why the speed signal is out it doesnt make sense. Probably the easiest way to correct the signal is with larger diameter wheels (~3% greater diameter)

I can confirm the the M35 has the same problem.

interesting... your m35 is a generation later (V35/M35) than S2 Stagea (R34), but I wonder how much they changed it for consult II etc? I notice on autos the transmission speed sensor appears to be on a different pin ("Output shaft rotation sensor signal (Vehicle speed sensor 1) - pin 58"); but your info does explain why I can't find a speedo output on the ECU; there apparently isn't one! damn. If only it were that easy...

Correcting with oversized tyres isn't always easy, and is expensive; could the rule of thumb that "if the speedo guage can understand the speedo signal and display correctly, the gearbox, ECM, BCM etc. must be able to" apply? I hope so... i don't like the idea of playing around with all those systems. I wonder what difference it might have if they were calibrated at the factory on the original spec' (10% high) speed sensor output? Although I'm hoping it's just a pretty basic signal that the kit will reproduce accurately. I mean I guess most cars that this kit is designed to be used with (ie. those with digital speedos) would have these other modern systems as well? There is a warning in the instructions about airbag precautions, so they must surely know *something* about it... I hope... ;)

DaveB Mentor

DaveB

Posted
Posted

OK guys done some further investigation of the wiring diagrams Mike posted up for the R34, and it appears as though the only time the signal is passed on (well, I have to treat the combination meter as a 'black box' and assume the signal is actually modified in some way by it) by the combination meter is to the TCM (Traction Control Module), however this is apparrently only present on rear-wheel-drive models.

I would hazard a guess that this signal could be modified with some degree of safety, since if you modify it for one circuit (the combination meters) you modify it for all circuits thereafter (assuming that it is a simple signal which the speedo correction unit is able to reproduce accurately, and that you have it setup properly, however the way to guage this should be to simply adjust things until the speedo is working as before).

This speedo correction kit specifically says 'handles AC output for Nissan cars', or something similar, which I thought was interesting.

So thanks Chook, I might have a hunt for that wire (black with white stripe) at the ECU...

DaveB

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