I have been working on a 545d last couple days, the problem was oil leak at bell housing, dumping large amount of hyd fluid, the owner wanted to split it and replace front trans seal. I thought we should go through the top and check it out, removed dash,fuel tank, steering, under the steering a large 4 bolt cover, gives good look at your convertor, the forward, reverse valve body, etc. Found one of the top pressure plug which requires an allen wrench was just finger tight, that was where the oil was coming from, but at the same time noticed that the wiring for the 2 silonoids on the top of the valve body was wasted, all the insulation had crumbled off it, surprised it was even driveable.So after rewiring that mess and putting her back together, along with replacing the front seal on the front pump driving of the crankshaft. Its working fine now. but the problems that alot of people are having could have alot to do with the wiring at the forward reverse silonoid or in my case the oil leaking out helped ruin my wiring quickly.