Rear parking sensors not working.

[spiky]

Hi.
Because I have a Fiamma bike rack, the reversing mirror is impossible to angle correctly. I'm looking into changing the mirror or similar.
However, there are parking sensors fitted. Four of them, one on each corner. Not great coverage, but could be helpful. Playing with the switch on the dash makes a bing, and then two lights appear at the top. This activates the front sensors, which work. The rears however do not. Following the wiring down from the switch goes to the passenger footwell where there is a box labeled Mitsubushi W001T76571 9922 which appears to be the control box. Looking under the bumper, the rear sensors are actually wired in, though I cant see how to disconnect them to check the contacts or swap them with the fronts for testing.

Any ideas, experiences or thoughts????

[g8dhe]

Our factory fitted version has a total of 5 sensors;
Nearside front
Rear nearside
rear offside
two facing directly backwards

The sensors themselves can be unplugged from the wiring loom under the bumper at the back. I have extended the cabling on ours so that they can be fitted either normally or on a Thule back box. Unplugging a sensor will bring up an error alarm on the display when it self tests at power up.