speedo re calibration

[Alan Reeves]

Can anyone send me a copy of how to recalibrate the speedo having changed the sender. It overreads by 5mph, not a lot compared to the previous bouncy attitude.

Has anyone changed to the new sender ( 2011 car )...well its a tad short for putting the end lock nut on?

Finally does anyone have a picture of the fuse box indicating what each fuse is for  ( ask JK )

alan

[Jonathan Kay]

Private Message sent.

[ChrisC]

Not sure what JK has sent, but I can confirm you can recalibrate your speedo.   You have to press and hold the button while the ignition is switched on.  This will display a number which is essentially the number of pulses per mile.   

There is an official chart showing the correct setting based on the tyres used, but this only covers tyres used by CC.   When I got my 2011 car I compared my sat nav speed to the speedo speed.  My speedo was 5% over, so all I did was reduce the number by 5%.   This resulted in a speedo that was 1mph under sat nav speed at 30mph and 2mph under sat nav speed at 70mph.  I can't confirm how accurate that is, all I can say is I never got a ticket in that car. 

[John Vine]

Hi Alan,

For info on how to reset the calibration (pulse) code, see Part C in this Guide.

Have fun!

JV

[Geoff Brown]

There is also an automatic way to calibrate the Caerbont speedo:

Setting The Calibration – Inputting The Calibration Number / Pulses Per Unit Distance. There are two methods to setting the calibration: (i) Manually inputting the PPU number. (ii) Using ‘drive to set’ facility.

The calibration mode is selected by switching on the ignition while simultaneously pressing the trip reset button. The pointer will travel to full scale and return to zero. If the button is released before the pointer returns to zero, the manual setting procedure will be selected and the LCD (odo.) will read ‘SET PPU’ If the button is released after the pointer returns to zero the ‘drive to set’ mode is selected and the LCD will show ‘DTS PPU.’ At this point, pressing the reset button momentarily will toggle between ‘SET PPU’ and DTS PPU’ .

Manually inputting  the PPU Number Set the LCD to display ‘SET PPU’ as described above. Press the reset button for 2-3 seconds, the LCD will show the calibration number currently set. Each digit within the calibration number will flash in turn for approximately 2 seconds. When a digit is flashing, each depression of the reset button will increment the digit by one. Once the last (right-most) digit has been set/reset, the whole number will flash. Press the reset button and the LCD will display ‘DONE.’ After 3 seconds the LCD will display ‘SET PPU,’ the setting is now complete. Switch off the ignition.

Drive To Set PPU: Set the LCD to display ‘DTS PPU’ as described. Press the reset button for 2-3 seconds, the LCD will display ‘∗00000.’ Drive exactly one mile. While driving, the odometer will count the number of pulses generated by the sender. Press the reset button for 2-3 seconds, the LCD will display ‘DONE.’ Within a few seconds the LCD will return to the ‘DTS PPU’ display. The setting is now complete. Switch off the ignition.

IMPORTANT – When driving in ‘drive to set’ mode the speedometer will register but not accurately. The speedometer cannot be used on a public highway in this mode. 

I will be utilising the 'Drive to set PPU' when I change to ZZS tyres - watch this space!

 

 

 

 

[John Vine]

I will be utilising the 'Drive to set PPU' when I change to ZZS tyres - watch this space!

I'd be interested to know what code you end up with, and how it compares with the code tables.  I've never tried that method as I've always thought finding a true measured mile would be tricky.

JV

[Geoff Brown]

Yes the exact mile could be the stumbling block but I aim to note what may be an exact mile using GPS or I could drive a certain route & note a feature where the mile should end. Trouble could be pulling in at the end of the mile.

Worth a punt! 

[John Vine]

Re #7:

I wish you luck, Geoff!  Apart from being able to stop exactly at the mile point, you'd be relying on satnav accuracy over a short distance.

This is the method I tend to use:

1. Enter the published calibration code for the tyre make/size.
2. Set the odometer to zero.
3. Drive a flattish route of say 30 miles with the satnav recording the distance.
4. Compare satnav miles with odo miles.
5. Calculate and enter a revised calibration code.
6. Repeat from step #2 until happy.

JV

[Alan Reeves]

I used Johns publication and have ended up with a plus reading of 3mph which I am happy with.

alan

[John Vine]

Good news, Alan.  It would be interesting to know how accurate your odometer is now (compared to a satnav, that is).

For the benefit of others who may stumble on this thread, what calibration code did you settle on in the end?

JV

[DJ.]

Useful thread thanks

 

My speedo has always over read by about 4mph, not a lot at 70, but a higher error proportionally at 30. The error was 13% at 30 and 6% at 70.

 

I don't want to risk it under reading so I added 5% and trying it this morning it is approximately 2mph over at 30, 50 and 70 so I'm happy with that.

 

The original figure was 39199, tyres are 185 x 60 x 14 Rain Experts and thenew figure 41160.

 

Duncan

[Alan Reeves]

Gutted from Sx

i used 040861 and got +3 mph and happy. Went out gave it a bit of speed and...bouncing started just like the old one.

i did not do the new earth and I will go back and check the gap

A

[John Vine]

Re #11:

That's useful info, thanks.  I think I'll add an extra table to my guide listing values reported by owners.  I've got three so far..

Extra ones welcome.  If you can, please state:

• Make of tyre
• Model of tyre
• Size (xxx/yy-Rzz)
• Old code used
• New code used

JV

[John Vine]

Re #12:

Thanks Alan.  I'll add that to my table.

The bouncing does indeed sound like an incorrect gap.  Try the LED test (if you can see the thing!).

JV

[Alan Reeves]

John, I have done a couple of blats around after opening up the gap and, fingers crossed its all stable.

[John Vine]

Good news!

JV