OK, straight in with the issues!
We bought our SLK from a guy who had been left it in his uncle's will, bizarrely. It's done 85k but seems to have rusty arches all round. I am hoping to god that the underneath isn't rotten.
Anyway, the car started with fairly little drama the first time, with fresh fuel and a fresh battery on it. It spluttered a bit but got going easier than I had thought it would. Happy days.
It had been stood a couple of years at this point, or so we thought. It looks like it may have actually stood for up to 6 years, going by the date of its last service. The history was pretty regular up to that point.
So the car was left at a garage for an MOT test to see what needs doing. Unfortunately they couldn't start it. I found the fresh battery drained also. My OH mentioned that the car had seemed to get worse and worse for starting as our 250 mile journey home progressed, so I wondered if the alternator was knackered. Leaving it overnight with a charged battery has seen no voltage drop, so I don't think there is a parasitic drain going on. Wiring in a multimeter in series also shows a max reading of just 0.15 amps, so doubt this would drain a battery.
Anyway, I digress, the starting issue: The car would not attempt to crank, but it did not show any start error type messages, which much research has told me can happen. I messed around a lot with the battery and cleaning the ends of the cables etc. No change. I then opened up the black box next to the battery to have a look at the K40 module. I took this apart and the board is spotless, no burned or damaged solder present.
I did notice that somebody at some point has added in a cable with an inline fuse holder to the wiring within the black box
No idea on this, and also there is a purple wire been added in the engine bay which I suspect may be some sort of additional earth someone has added at some point.
Anyway, I pulled and inspected all of the fuses on the K40. No problems. I put it all back together and clipped all of the connectors back on and the car started first time!
I tried it again after we took it back home, and it started no probs. I thought I had somehow solved the problem. Tried it this morning and we are back to no attempt to start or crank. Can anybody offer any suggestions? Sorry for the long post.