Help re-calibrating speedometer

[Sandfire]

I am trying to re-calibrate the speedometer on an '05 Caterham with the standard Caterham gauges. The gauge with the program button on the front.

 

I am following the Caerbont Automotive Instruments instructions which seem very straight forward. "calibration mode is selected by switching the ignition on while simultaneously holding the programming button down and waiting 3 seconds. After 3 seconds, release the button and the odometer display will flash in calibration mode, showing the previously set pulses/mile".

 

Unfortunately, after a few attempts I cannot enter the calibration mode suggesting that I am applying these instructions to the wrong gauges or I am simply doing it incorrectly.

 

Has anyone re-calibrated their speedometer following a similar protocol.

[Bucknekked]

Hi Sand,

 

This is how Randy Cross explained it to me. The key for me was to push the button first before turning the key on. I hope this helps.

Cheers,

Buck

 

 

There is a rubber button. Press that and turn the car ignition on (I do not think the car needs to be started). Wait 3 seconds.

 

It should now be in calibration mode and the odometer display will flash.

 

The first number can be changed by pushing and releasing the button. Holding the button down for 3 seconds will set the number and then it will sequence to the next number to the right.

 

The total number should be.... Number of rear tire revs per mile x number of teeth. Which is 43 teeth

 

Assume tire is 21.5" dia or 21.5*pi = 67.54" travel per revolution. Mile is 63360 inches. or 938 revs per mile.

 

938*43 = 40334

 

Your number should be 0 4 0 3 3 4

[bsimon]

I cannot enter the calibration mode

 

There were 2 different electronic speedos in the first decade of the 21st century. The early one has DIP switch settings for crude calibration. The later uses the trip odo button method.

 

You may have an early speedo that is set with switches.

[scannon]

There were 2 different electronic speedos in the first decade of the 21st century. The early one has DIP switch settings for crude calibration. The later uses the trip odo button method.

 

You may have an early speedo that is set with switches.

 

My '04 Caterham's speedo came with the DIP switches. I could not calibrate it to the Hall effect sensor reading the front wheel studs. I had to buy a newer speedometer and was able to calibrate it.

[Sandfire]

Yes, turns out I do have the DIP switches and they were set to 8386 or 0000001010. Calculating the calibration number is tricky as I don't know what sensor is being used. Seeing as the speedometer is a full 5mph off I think I can probably get pretty close by simple trail and error. Just changing the DIP switches to 1100001010 or 8483 got me a lot closer.

 

I suspect the odometer is off as well then and the car does not have as many miles as shown.

 

Thanks for all your help.