Parking sensor PROBLEM (electric control unit) ECU

[ASJ]

Hi every body;

the front and rear parking sensors for my Automatic transmission CLK Mercedes 230 model, year 2000, has stopped working.

I found out that the Electronic Control Unit (ECU) for it was faulty and was not working.

I replaced the ECU, started the car, drove forward and front sensors worked, great, I said.

But when I reversed the car to test the rear sensors it suddenly stopped working gain and the (ECU) is blown again.

I even dismantle the ECU box to see if there are fuses inside, but there was none.

All fuses of the car are ok,

Does any body Know why the ECU keeps blowing up ?
But Shouldn't the car fuse blow up before the ECU ?

Many Thanks folks