R31 Skyline Speedo Calibration

This modification will also work on any electronic
speedo that uses the UAF2115 speedo driver IC.

Thanks to SKY-031 and Bozz from the R31SKYLINECLUB.COM for putting
me on the right track to finding this information regarding electronic speedo calibration.

Click here for info about calibrating the speedo in a TE Magna -

To adjust both the speedo and the odometer, you need to fit a module in the speed sender wire to modify the number of pulses -
Here's a solution for that - Jaycar's (revised) KC5435 Digital Speedo Corrector

Here's a diagram of the connections you'll need to make with this kit. Speed wiring.jpg (35549 bytes)
1. Join onto the Yellow for 12 volts to power the kit. (Unless you're picking up power elsewhere......)
2. Join onto the Black for the Earth connection for the kit. (or at any other convenient point ie. earth screw near RHS kick panel)
3. CUT the RED wire. From the Speed Sensor is the input to the kit.
4. The output from the kit will join back onto the other cut end of the RED wire.

Here is the data sheet on the IC used in the R31 speedo -  Speedo IC - uaf2115.pdf
Fitting a pot as described below is the cheapest way to correct the speedo but it doesn't correct the odometer.
Here are some pictures of the speedo board where you need to make the calibration mod :-
Fitting a pot as described below will only calibrate the speedo. The odometer will still be out because this mod only adjusts the calibration of the moving coil meter (speedo).

DCP_1078.JPG (40154 bytes) This photo shows the circuit board and the pins the speedo is connected to. Carefully prise the speedo away from the circuit board pins evenly.
DCP_1075.JPG (72728 bytes)

This shows the board that is mounted on the RHS of the speedo (looking at the face of  the speedo). The IC can be seen on the left. The stepper motor that drives the odometer is the large round item in about the middle.

R6 is in the bottom left hand corner. This resistor is used to allow for manufacturing tolerances in the speedo and is used to trim the speedo. It won't calibrate the odometer, but it can be used to calibrate the speedo.

R4 is on the far RHS. If a 100K ohm multi turn pot is fitted here, then the adjustment will calibrate the speedo only because it only adjusts the pulse width, not the frequency.
Measure the value of R4 after removing it and set the pot to this value before fitting it - when you go for a drive ( to the dyno ), at least you'll be starting with the same error you had before.

DCP_1077.JPG (72827 bytes) This photo shows the pot fitted in place of R4. It is on flying leads so that it can be run out from the dash to allow for easy calibration. A fixed resistor of the same value as the pot could be fitted after calibration is complete - it will probably need to be made up of two or more resistors in series and / or parallel to obtain the correct value - check a Jaycar / Dick Smith / RS / Farnell catalouge for available values.

( The photo shows a standard trim pot as I didn't have a multi turn pot available at the time. The end result is the same. )

100kpot.JPG (4025 bytes) This is a 10 turn 100K Ohm pot. Solder the wires onto the two left hand pins.
speedoIC.jpg (49720 bytes) Here is the block diagram of the UAF2115 speedo IC. The resistor that you are changing is the one across pins 8 and 10 of the IC.
The resistor that hangs off pin 4 of the IC is used to allow for manufacturing tolerances in the moving coil meter ( speedo ) - It won't correct the odometer, but can be used to correct the speedo.
In the factory, the odometer would be calibrated first and then the value of the resistor on pin 4 would be adjusted to trim the speedo.
calibrationpot.JPG (22146 bytes) Here is the calibration pot coming out from under the dash. It has a couple of layers of heat shrink over it to insulate the connections.

When you have the calibration pot set up, the best way of achieving calibration is to go to a dyno shop and whack the car
on their rolling road. It might cost a few dollars, but it's much quicker, safer and more accurate than driving along side another car.
These days GPS is readily available - have a passenger help out.


R31 Skyline - Low fuel light sensor replacement / installation

The low fuel warning light was not fitted on GX models.
It can be easily connected as the sensor is already mounted in the pump assembly.
You just need to run a wire from the pump connector in the boot behind the back seat to the dash and install a globe.
The sensor is also prone to failing. Replacement is outlined below.

lowfuelwire.JPG (83984 bytes) This is the wire that runs to the dash. The pins used in the fuel pump connectors are the same as the ones used in other cars. This one came from a VL Commodore loom. It makes a neat job. The same connector is used on the other end of this wire at the dash. 
The other alternative is to cut the low fuel wire on the pump side of  the connector and use maybe a Utilux crimp connector. 

Just remove the dash and the circuit board where the warning lights are and hold the dash up to the light and you can see where the low fuel light has to go. You'll probably need to buy a globe and holder too.

lowfuelconn.JPG (99900 bytes) With the fuel pump unplugged, you can see where the new wire has to be fitted.
If the dash end has been connected, then you can test the light at this stage before connecting the sensor. Turn the ignition on and the lamp test feature should cause the low fuel light to illuminate. Now start the car and the light will go out. Next, test the light by connecting the new low fuel wire to a good earth in the boot somewhere - a fuel pump cover screw should do the trick and the light should illuminate.
lowfuelconn2.JPG (26718 bytes) Here is the new wire plugged in.
LowFuelWire2.JPG (80919 bytes) Plug the low fuel wire into the white connector as shown - It's the yellow wire.
lowfuellight.jpg (30363 bytes) The light comes on with about 10 litres remaining.

Sensor replacement

The sensor simply provides an earth (when it is dry) for the low fuel light.

tank.JPG (58270 bytes) The pump assembly needs to be removed from the tank. It will probably be quite dusty so give it a good clean before you open the tank - compressed air would be good.
Depressurise the fuel system before removing the hoses and cover them with a rag so that you don't get splashed when they come off.
The pump assembly is a bit awkward to remove so do it carefully. The filter on the pick up sticks out a bit and the float arm can be seen in the next photo, so you can see that it has to manoeuvred carefully.
pump.JPG (45919 bytes) Here is the pump removed from the tank. You can see the low fuel sensor on the LHS with a white wire attached to it.
Replacement sensors are available from auto instrument shops. I couldn't find any original parts, so a generic item was chosen. This one was $15 trade.
fuelsensor.JPG (21396 bytes) Here is a picture of the fuel sensor. The one on the left was faulty - looked like it had been fried - I don't know why it failed because it was never connected previously.
The new one came with a bracket attached which had to be removed.


Fusible links and Relays

5.jpg (51093 bytes)


RB30 Twin Cam Conversion Page

tacho.jpg (19561 bytes) Tacho drive mod.
If you build an RB30DET and use programmable management, then you may need a circuit like this to combine the three ignition signals to drive the tacho.

VL Turbo Engine Harness Wiring Diagrams

VL1.jpg (262939 bytes)Harness 1

VL2.jpg (202197 bytes)Harness 2

VL3.jpg (229472 bytes)Harness 3

VL4.jpg (231124 bytes)Harness 4

VL5.jpg (152531 bytes)Harness 5 VL RB30.jpg (248999 bytes)ECM Pin Outs



If you've removed a Series 3 auto and fitted a manual or a Jatco auto trans,
then you'll need to wire up the neutral start, reverse lights and the speed sender.

R31 - Series 3 Reverse Light Wiring

You would have disconnected 4 trans wiring connectors in front of the battery.
1. Grey 3 pin connector.
1. Brown 8 pin connector.
1. Grey 2 pin connector - ( start inhibit ) - - two fat wires - 'White/red' & 'Black/yellow'.
1. Grey 8 pin connector.

Find the 8 pin grey connector. It will have a “Red / blue stripe” wire in it. This is the reverse wire – connect it to one side of the reverse switch on the manual box.

In the same connector, the wires on either side of the reverse light are “White / green stripe”. These are +12v ignition – connect one of these to the other side of the reverse switch on the manual trans.

You can test the reverse lights before doing this mod by bridging (or shorting, yes, that's what the switch does or linking or whatever ya want to call it. The term 'short' doesn't always refer to a bad situation) the 'Red/blue' and 'White/green' wires with a wire link, then turn on the ignition and the reverse lights should illuminate.
Short = 0 ohms
Link = 0 ohms
Bridge = 0 ohms
Piece of wire - 0 ohms
Closed switch contacts = 0 ohms
Therefore  Link = Short !

R31 - Series 3 Neutral Start

You would have disconnected 4 trans wiring connectors in front of the battery. 
1. Grey 3 pin connector.
1. Brown 8 pin connector.
1. Grey 2 pin connector - ( start inhibit ) - two fat wires - 'White/red' & 'Black/yellow'.
1. Grey 8 pin connector.

On a SERIES 3 Auto, the start inhibit function is done in the inhibit switch on the trans - there is no neutral start relay.
The grey 2 pin connector in front of the battery contains the 2 wires that go to the inhibit switch on the trans. (To get the car going, you can just put a link across these two wires - 'White/red' & 'Black/yellow'..)
This is where you would fit a relay  and connect the 'White/red' & 'Black/yellow' wires to the contacts of the relay. The relay will need to be triggered by the neutral switch from whatever trans you have fitted.


R31 - Series 3 Speed Sender

Here, you need to look behind  the battery. You will see a 'white 6 pin connector' and a 'white single pin connector'  together.
On the 'white 6 pin connector' there is a red wire - this goes to the speedo. Connect your speed sender signal here.

Fitting a VLT Jatco auto to a Series 3 Skyline

It physically fits OK, but the rear mount needs to be modified. I used the cross member from the VL - the LHS needed to have the holes opened up a little to fit the Skyline. On the RHS, I welded a piece of angle iron to the bracket because it was no where near fitting the mounting points on the floor pan.
The tail shaft fits OK.
The selector rod needed to be shortened.
The VL drive plate must be used so that the torque converter will fit.
The VL turbo auto trans control computer will need to be fitted too as these autos are completely different to the Series 3 auto..
The biggest hassle was stripping the auto trans control wiring from the VL dash harness. You will need the VL workshop manuals with the colour wiring diagrams to help here. They are excellent diagrams !
Once the auto trans control wiring is stripped from the VL harness, the layout will need to be altered so that it will fit neatly into the Skyline. I mounted the computer behind the dash above the drivers left knee.
It will need a power feed from the fuse area and a speed signal. Connect the kickdown switch  and get throttle position and throttle switch wires from the engine ECU loom near the ECU.
You will also have to fit a neutral start relay because the S3 doesn't have one - the neutral start was done in the inhibitor switch on the original Series 3 auto, which has now been removed. The VL diagrams make this clear.
When the S3 auto is removed, 4 plugs will be disconnected. There is one 2 pin plug in front of the battery with heavy gauge wires 'White/red' & 'Black/yellow' - this is where the neutral start relay contacts need to be connected to.

The speed sender ratio will now be incorrect. Fit Jaycar's Speedo Corrector kit as described at the top of the page.

Here's a couple of photos of a Kienzle Ratio Box used to calibrate a cable driven speedo. 


KienzleRatioBox1.JPG (551365 bytes)

KienzleRatioBox2.JPG (554235 bytes)


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This page was last updated 15/03/2015
Anyone wishing to reproduce this information in any form may contact me for permission.
Copyright 2000