Nokia car kit switching off when wipers on

Hi,
I bought a car recently that has a Nokia CK-15w car kit installed. Have found it a very handy piece of kit so far. The only thing is that it turns off if I have the front and back wipers on!! If I have the front windscreen wiper on it'll be fine but about 10secs after also turning on the rear wiper, the car kit will turn off. Same applies if rear wiper is on followed by turning on the front wipers. The car kit comes back on when one of the wipers is turned off.

Any ideas anyone?!?!

The gnd connection of the kit is probably picking up a live when the wipers switch on. get into the power connection of the kit and measure for 12 volts with the wipers off then on.

Or else disconnect the black wire and hold to a metal part behind the dash or to the body of the radio as this will provide your ground and test it then.