i have (thanks to your help) found the sensor behind the front bumper.
yes . it reads"+3"most time but ocasionally "+2".(absolute)

to install:

i am told to cut new and old leads and join them but this would introduce another element.
does anyone know where the display end terminates?
thank you all

__________________
kel347
1986 SEC560 250000km
1976 F100 (No more..went gardening and took out some trees..damaged driver and destroyed vehicle...plastic is fantastic but steel is for real)
2000 Landcruiser
1981 corvette