P0504 'Powertrain' Fault Code

[JasTDi]

Hi all,

I'm new to the Focus world.

I had an interesting fault occur last night that I thought I would hare with the community.

I have a 2010 TDCI LV Focus Manual with 53k km on the clock.

I hooked up a trailer last night for the first time and did a light check.
All lights checked ok with the ignition on. I turned the ignition off and pushed the brake pedal again.
My father was checking the lights for me on the trailer and commented that it didnt seem right.
I pushed them again and then figured it was just a qwerk with the car.

Drove home the 2km without a problem. When pulling into the driveway the dashboard lit up with a Engine Malfunction fault.

I couldn't do anything about it as my OBD reader had stopped working.

This morning I went and picked up another reader and on the way to Jaycar the car went into limp mode.

When I scanned for faults it came back with a P0504 'Powertrain' fault.
I researched and it is linked to a generic OBD fault for the brake switch.

I figured it was linked to putting the brakes on with a trailer attached while the car's ignition wasn't on.

Hope this helps anyone who come across a similar issue.

Cheers
Jason

[marg99]

Does this mean the trailer wiring needed a special module fitted so the car computer did not register a fault on current draw?

[JasTDi]

The car came with a factory fitted module that looks dealer fitted. Thats why I thought it was all a bit odd.