sounds like the one i had on a navara d22 it was for increasing the revs so engine warms up quicker when stood it also came in handy when jump starting someone
cheers Andy
I seem to remember seeing a post in the thread about heaters by someone who said that they had a ceramic heater built in and that was why he had heat straight away from his cab heater , maybe this is what you have and the engine rev increase is to get the alternator up to higher output to cater for it?? Rick