Hi can anyone tell me what the two plugs are for, beneath the fuse box behind the left sidecover, one has a rubber end cap the other has a hard plastic sleeve cover on it.I have tested the one with the rubber cap that works only with ignition on not Acc it only has 3 wires I wish to use this for my Aux power but don`t know the Amp rating I have been told about the toggle switch behind left side of narcell controling a plug which is under the seat but that particular plug dont seem to do anything, can someone shed some light on this. much appreciated

Rubber endcap doodad is your Deutsch connector for the ECM access , either for the dealer Digitech workshop laptop OR your own tuner dongle

DON'T TRY TO DRAW POWER FROM THERE !!

I'd have to see a photo of the other plug as I don't have a Dresser myself , but I have worked on plenty Re the ECM re-tuning

thank you retroman I suspected one of them would have been for sert much appreciated. I wouldn`t have cut or changed anything until positive.
I will investigate further cheers mate

I was under the impression that there is a connection for a trickle charger.

What i meant was if you buy a trickle charger that may be the plug you need to plug it into.