Fridge - 12 volt problem

Car 13 pin, Van Senator Indiana Series 5. - 12N and 12S pins

Fridge works fine on both mains elec and gas. When switched to 12 volt for travelling the green indicator light switches on and off at around one per second

I had a quick look in the vans 12S connector but cannot find a Bailey wiring colour code to help idetify the fridge feeds.

I know that the fridge has a permanent supply for the cicuit board besides the car fed live and return power lines..

The 13 pin supplies a steady 12 volt feed at the car.

Any ideas would be gratefully received. I am puzzled to say the least even though the fault is not critical, I would like to cure it