Earth problem

In the diagnostic connector Pin 4 is earth and Pin 5 is a dirt signal I have a problem with the Earth of Pin 5 and the car does not turn on is a 2001 party if I connect a direct ground cable the car on but not ce if it will be the right thing. I think that ECU herself should try that land and is not borne by Otrs Rason

Greetings Annthony, your problem is strange, locates a screw where the lands of the ECU arrive, being in the pilot's seat, on the left touches the floor and through the edge where the carpet ends, under it this hidden is such a screw, you may need to take out the small plastic floor that is close to be able to lift the carpet, check if the screw is lazy, sulfatado or rusty, tell us how it went.