Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPHThis is the html version of the file http://www.skyline6969.btinternet.co.uk/r32speedo.pdf. G o o g l e automatically generates html versions of documents as we crawl the web. To link to or bookmark this page, use the following url: http://www.google.com/search?q=cache:FTF20Dzz-LgJ:www.skyline6969.btinternet.co.uk/r32speedo.pdf+r32speedo.pdf&hl=en&gl=uk&ct=clnk&cd=3 Google is neither affiliated with the authors of this page nor responsible for its content. These terms only appear in links pointing to this page: r32speedo pdf Page 1 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH By Skyline69_uk Page 1 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 2 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Introduction.............................................................................................................................................. 3What the different bits do......................................................................................................................... 4Speedometer Cable ......................................................................................................................... 4Vehicle Speed Sensor (VSS) .......................................................................................................... 4Electronic Concentrated Engine Control System (ECCS) ............................................................... 5Super HICAS.................................................................................................................................... 5Advanced Total Traction Engineering System for All-Electronic Torque Split. (ATTESA-ETS) ..... 6Systems on the R32 that use the VSS.................................................................................................... 8How the conversion is done and it’s effect on VSS ......................................................................... 8How the ECCS uses the VSS .......................................................................................................... 8How the Super HICAS uses the VSS............................................................................................. 12How the Super HICAS uses the VSS to control the Power Steering............................................. 15Do the ABS and ATTESA-ETS systems use the VSS?................................................................. 16Summary ............................................................................................................................................... 18Page 2 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 3 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Introduction The aim of this document to help the new and old owners of a Nissan Skyline GT-R R32 to come to a decision as whether to mechanically convert the vehicle’s speedometer from KPH to MPH or leave the speedometer in KPH. I found myself in this same decision making position after I purchased a 1994 GT-R in Japan through an agent (a very good one at that) and had to make the same choice myself (I chose not to convert but it is a matter of opinion). I had noted that a number of owners on various forums were claiming that they believed the conversion was causing problems in the normal operating conditions of the vehicle – this document is the result of the research prompted by those owners (thanks to all of you ☺). To aid in this decision I have highlighted potential problems that this conversion may create. I have researched this project using the R32 Service Manual (highly reliable but scanned in a very fuzzy way!), internet research (not very reliable) and some garages who carry out conversions (fairly reliable but wish to remain anon). Other information has been gained from the sites of manufacturers of vehicle speed sensors, anti-lock brake systems and of course books I currently own (Vehicle and Engine Technology by Heinz Heisler and Internal Combustion Engine Fundamentals by John B. Heywood amongst others).If I get something slightly incorrect or just plain wrong please let me know! Page 3 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 4 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH What the different bits do Speedometer Cable This is a mechanical rotating cable that is attached to the transmission of the vehicle and rotates at a rate that is in a fixed ratio to the speed of the vehicle i.e. road speed of the vehicle if no tyre slip is occurring. Vehicle Speed Sensor (VSS)1This is a device that converts the mechanical rotation of the speedometer cable to an electrical one. In most cases this will either be an optical VSS or magnetic impulse VSS like that used in ABS sensors. The VSS works off the speedometer cable and is located inside the speedometer at the back of the instrument panel in the R32. The wiring diagram does not give an indication of the type of VSS as normally the LED type would have two small arrows emitting from it. The optical types use a photo cell, light-emitting diode (LED), and usually a two blade mirrored reflector to generate an electrical pulsed signal. The LED is powered and emits light whenever the ignition switch is on. When the vehicle is in motion, the speedometer cable spins the two bladed reflector. The reflector rotates through the LED light beam breaking the beam two times for each revolution of the reflector. Each time a mirror passes through the LED beam, the light is reflected to the photo cell. When the mirror isn’t breaking the beam, no light reaches the photo cell. Whenever light hits a photo cell an electric signal is generated. The signal from the VSS is normally used for the following reasons in most modern vehicles… •Cruise Control •Auto Transmission Shifting•Digital Speedometer •Idle and low speed fuelling map •High speed economy mapping modes (highway mode) •Idle air control valve •EGR valve (emissions control) •Canister purge cycle (emissions control)•ABS and Traction Control operation 1http://www.wellsmfgcorp.com/counterpoints/Counterpoint4_2.pdfPage 4 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 5 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Thanks to gtst_lad for the photo Electronic Concentrated Engine Control System (ECCS)This is the main brains of the vehicles control systems regulating all the engines operations e.g. fuel injection system (length of fuel pulse), idle control and engine temperature control etc. Super HICAS2The 4 wheel steering system that Nissan developed to aid emergency lane changes and to make turn in on heavy vehicles feel more nimble. SUPER HICAS works first in assessing the driver's intent. Itdoes this by assessing not only the angle at which the wheels are turned, but also the rate at which they are being turned and the acceleration towards that rate. All this information is used with the vehicle speed to calculate the angle and rate at which the rear wheels should be steered. If you don’t like the way the HICAS system feels then you can get a HICAS locking unit fitted. 2www.northwestnissans.comPage 5 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 6 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Check out http://www.bilski.net/movies/HICAS.avi for a video of it in operation in diagnostic mode on a 300zx TT. Advanced Total Traction Engineering System for All-Electronic Torque Split. (ATTESA-ETS)3This is the 2/4 wheel drive system that the Skyline uses to great effect when traction conditionsdemand it. Nissan's technologically advanced ATTESA-ETS computer-controlled which is an on demand all wheel drive system keeps track of wheel rotation and the car's acceleration. If the 3http://www.everything2.com/index.pl?node=ATTESA-ETSPage 6 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 7 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH computer detects that the rear wheels are losing traction it can supply up to 50% of available torque to the front wheels and restore traction (hopefully!). This should prevent spinning into the hedge and allows for harder and faster cornering than a normal RWD vehicle. Normally the car will be operating just like a rear wheel drive car (0:100 traction) but if for any reason the rear wheels lose traction and begin to spin up the front wheels gain torque by means of a hydraulic centre limited slip differential and a wet multiclutch. As a result the front end pulls the car while the rear end pushes leaving the car in a more or less stable condition. One of the things this system does that is not so well known is its action in corners. When it senses you are in corners it lessens the torque to the front wheels the higher the cornering g-force – the opposite of what you may think would happen. This allows the tail end to be kicked out on request by cornering really hard! Andy’s (R32_Combat) little TCS device controls this and in fact after a bit of research this is the same sort of device that racing Skylines were fitted with to make cornering faster on the race track in differing conditions (wet and dry). ATTESA-ETS is commonly found in the Nissan Skyline GT-R and Nissan Pathfinder. The latest generation Skyline V35's 250GT FOUR model utilizes ATTESA-ETS also. The Nissan Skyline GT-R Vspec and VspecII use a more advanced, racing-tuned system called ATTESA-ETS Pro. Also, a similar, but not as advanced ATTESA (Advanced Total Traction Engineering System for All-terrain) isemployed on many Nissans and Datsuns: the Skyline GTi-R and GTS4; a special model of the Bluebird/Altima called the SSS ATTESA and the Pulsar. ATTESA is mechanical instead of electronic in nature. Page 7 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 8 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Systems on the R32 that use the VSS How the conversion is done and it’s effect on VSS The conversion is done by putting a mechanical gearing device (see pic) on the cable that leads fromthe transmission to the back of the speedometer. This reduces the cable’s rotating rate to 5/8thof the normal rate hence making the speedometer show MPH and the odometer tick over in miles instead of kilometres. The VSS output signal now pulses at a reduced rate 5/8thof the normal frequency and the line voltage will also be reduced due to the lower frequency output. It should be noted that removing and replacing the needle on the speedometer to change the dial face can result in the needle breaking in a very large percentage of cases! How the ECCS uses the VSS Some of the following information is general stuff that all modern vehicle ECUs do with the VSS signal in any vehicle produced from the 1980’s on. I will state and show where possible references to tests in the service manual that indicate the Skyline is doing the same (if it isn’t then it would be more like 1950’s car). Below is the wiring diagram for the ECCS from the R32 service manual. Page 8 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 9 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH It can be seen that the VSS is coming in on pin 53 (bottom left of ECCS). It also has a connector (No.16) showing that the VSS is branching off to other devices (more on that later). The normal use of the VSS in all modern ECU’s would be •Cruise Control •Auto Transmission Shifting•Idle and low speed fuelling map •Idle air control valve •EGR valve (emissions control) •Canister purge cycle (emissions control)•Speed limiter Less likely but not impossible on the Skylines would be •High speed economy mapping modes (sometimes called highway mode) Cruise control and auto shifting are mentioned in the service manual relating to the VSS signal but we will not go into them here as that is not the point of this document. As can be seen from the service manual idle speed control inspection section (see below 5-4) the idle control is set to kick in at speeds below 5mph, if you add a geared converter (GC) to the speedometerthen this will relate to a road speed of below 8mph for the idle fuel map etc. It’s not a big deal but in heavy traffic it can mean a bit more fuel used and a bit more coking up of the engine. Unfortunately on the engine mapping front that’s all I could find directly in the service manual. What it does mean is anyone thinking of cutting the line to pin 53 should think again as it couldleave the vehicle in idle control mode permanently! I say “could” as the VSS signal could havea base carrier signal which if disconnected may be detected by the ECCS and what is known aslimp home mode could be activated. Either way it is not good news disconnecting pin 53. Page 9 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 10 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH This still leave the other stuff that the VSS is normally used for but is hidden deep inside the ECCS software e.g. Exhaust Gas Recycle and the possibility of other highway fuel mapping modes that are not kicking in due to a reduced VSS signal frequency.A benefit to the GC vehicle is that the speed of the limiter will be raised by 1.6x i.e. on a Skyline to 180mph! Page 10 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 11 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Page 11 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 12 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH How the Super HICAS uses the VSS The Super HICAS system appears to work in 3 modes… •Low Speed – HICAS is inactive •Mid Speed - moves the rear wheels initially in the opposite direction to the front wheels and then in the same direction if the steering wheel is turned quickly else if the wheel is turned slowly they are meant to turn in the same direction to the front wheels as in high speed mode•High Speed - moves the rear wheels in the same direction to the front wheels I believe the mid speed mode seems to be activated at 37mph (60mph in a GC vehicle) due to the test in the service manual (see diagram). I can find no test in the manual for the high speed mode although I reckon it may be about 50mph to 60mph (90mph in a GC vehicle) as two posts on an USA owner’s site stated that on very high speed sweeping bends 90mph they can feel the HICAS twitch if they drop speed mid bend on gearing converted (GC) vehicles (and that it was very scary indeed). It would also be (in my belief) the speed at which an emergency lane change manoeuvre would become active and welcome!It should also be noted that the HICAS twitch may also be due to a steering wheel change as it seems that changing the wheel can crack or break the connections in the boss sensors.Note: if you have an auto spoiler then it too will be affected on the GC vehicle. Page 12 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 13 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Page 13 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 14 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Page 14 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 15 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH How the Super HICAS uses the VSS to control the Power Steering It’s simple really as the HICAS unit controls the power steering solenoid allowing the VSS input to be used to control the weight of the steering and once again this will be incorrect for a GC vehicle were the mapping used for example is 50mph when it should be the mapping for 80mph. Page 15 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 16 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Do the ABS and ATTESA-ETS systems use the VSS? This is when it gets interesting as up to now most of the above can either be fixed by locking the HICAS and ignoring the other small changes (power steering weighting, idle, EGR, purge control and maybe some other speed related fuel mappings). It appears that the VSS is NOT being input into the ABS unit or the E-TS control unit (phew!). The ABS appears to be 3 channel ABS on the R32, 2 sensors on front and 1 on rear while I believe it may be 4 channel on the R33 and R34 model. This is not to say the E-TS is not using the vehicle speed as it is taking inputs from the ABS speed sensors but these are not affected by the gearing conversion. It may also be taking inputs from the ECCS which does have a connection to the VSS but from the wiring diagram it does not seem to be using any connection that would suggest it uses a VSS related pin but I cannot be 100% sure without knowing what the ECCS software does. Page 16 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 17 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Page 17 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon. Page 18 Effects of converting a Nissan Skyline R32 GT-R speedometer from KPH to MPH Summary Changing the speedometer will produce the following… •Speed limiter will be raised to 180mph! •Maximum cruise control speed may be increased by 1.6 fold •HICAS will not work correctly maybe leading to instability at speed. •Power steering will be weighted incorrectly•Auto Spoiler will not work correctly •Emission control may not work correctly •Idle fuelling will not work correctly but should be minor •Some undocumented fuel mappings may not work correctly Page 18 of 18Created by Skyline69_uk (GT-R Owners Club). Rev: 01/04/2005 Disclaimer : Data and information contained within this document is provided for informational purposes only, and is notintended as a guide to modifying your vehicle. I shall not be liable for any errors in the content, or for any actions taken inreliance thereon.