[alexbrown64]

Finally got around to wiring up the Yellow Box Speedo re calibrator. Jumped under the car with some solder, heat shrink etc.. and 5 minute job. Only 3 wires come off the 95 XJ speed sensor.

These are orange, orange/white and black/light blue.
1. Splice in the red wire from the Yellow Box to the orange speed sensor wire (this gives power to yellow box).
2. Splice in the black wire from the Yellow Box to the black/blue speed sensor wire (earth for yellow box).
3. The orange/white wire from the speed sensor is cut in half. The orange/white half from speed sensor splices to yellow wire of Yellow box (this takes input from speed sensor and sends it to Yellow Box for adjustment.)
4. Then finally splice green wire from Yellow box to the orange/white wire coming from speedo (this is the corrected output from Yellow box and will go to your speedo.)

I turned on ignition and all systems were go. Just need to adjust Yellow Box. See previous posts on how that is done. Took about a minute using the + button on the Yellow Box.

I downloaded DigiHud, which is a great free gps speedo for your phone. Then i set the phone up on the dash and went for a test spin. First time out and no more adjustment necessary. XJ speedo was exactly the same as phone gps through all speeds.

I can now swap tyres etc, and adjust my speedo in cab with dead accuracy in 1-2 minutes.

A big thumbs up for the Yellow Box V5 and highly recommended.
Cheers,