OK, so having eliminated the alternator. Next, let's eliminate the starter. Again, disconnect the battery, remove the big black wire from the starter, and cover it to prevent contact with anything else.Instead of thinking electrics, think water, header tank in the loft.
The height of the tank is pressure, (= voltage).
The size of the pipe is the flow rate, (= current).
The size of the tank is capacity, (= battery Amp hours, Ah)
So our tank is in a bungalow, so the pressure, (= voltage) is quite low at 12 volts.
The apparent high current drain, (large pipe/big leak), means the header tank, (battery), is emptying quickly.
So, you're looking for a big leak, because all the taps are off, but the tank is still emptying, and wherever it's flowing will get very wet if it was water, (or hot with electricity).
As an example, both headlights on will draw about 10 amps.
Finding the problem will be a process of elimination. The alternator is an obvious suspect, as it contains components that should only allow high current, (to charge the battery), to flow out of it, but a failed one can allow current, (our leak), to flow in too.
Mac.
I tried thatTake the piggy back fuse out altogether to see if it makes any difference.
That a really good suggestion, thanks. I’d not thought about the starter or power steering, I’m sure I’ll find it, and better to be a 5 amp draw than a 1 amp as it should be very obvious……when I find it that is!I'm a bit busy this morning, so, if the starter is eliminated, the next move is to remove fuse 88, the strip fuse on the battery positive connection. Usual precautions.
If it's easier, you can disconnect the starter there too.
Mac.
Edit: In fact, if you remove fuse 88 first, and connect your meter across where it was, (maybe fix the leads under the retaining nuts), and you still see 5 amps, then the current is being drawn by the car's electrical system.
(If no current, then it's starter, alternator or power steering, the only things before fuse 88).
The cable going away from fuse 88, goes to the main fuses, both the fuse panel, and the under floor.
I'd remove fuses, one by one, (and don't replace them), until the current drops
Mac
Yes, that’s what I’m thinkingThe radiator fan, and it's controller would be my prime suspects, as the fans can run when car is off, to clear residual heat.
Suggest a scan, and clear the DTCs, there'll be loads I think.
Then scan again after a few trips, to see if there's any clues.
The FCM could have a partial short, not enough to run the fan, but enough to give the 5 amps. When the cooling fan runs, it draws more than 5 amps.
I'd put an FCM by, as insurance.
Mac.
I think the FCM is a semiconductor device, if so, partial failure could result in current leakage.Yes, that’s what I’m thinking