Have I blown my ecu, or something else?

[itz_baseline]

Ok, stupid I know. Lockdown means battery was very low. I tried to start and it turned over a bit but knew it needed a charge.

Plugged my mains battery conditioner in and left it for a few hours. When I returned it was at about 50% so decided to try and start it.....didn’t even to think to take off the mains charger to the battery.

I cracked it over and it just started then dead. Nothing. I put the keys in and switch the ignition on and I get clock, radio, dash lights etc etc, but not much else electrically. It won’t even try and turn over now. The electric windows don’t work, the indicators won’t work, can’t lock the car. Electric seats don’t work.

Doh, school boy I know and lesson learned to think things through properly rather than bull in a china shop approach, but what’s the most likely culprit. Blown ecu or lots of blown fuses and relays? Best approach to take? I have AA home start, just ring them and leave them to try and fix it? If I’m know what it is I could buy some parts in case AA man doesn’t have them....they like that as it goes down as a ‘fix at roadside’.

Car is an 03 Mercedes ML.

[Order66]

First things first - get the battery charged and check it is holding charge, then try to start it. You can't diagnose anything electrical without a known good battery with full charge being attached.

A battery "conditioner" can take several days to charge a battery from flat. It could not "blow" the ECU - you simply have a flat battery.

[itz_baseline]

Thanks. Just tried jump starting from another car and it’s the same situation.. Even after hooking up to another car for 5 minutes the electric windows in my car wouldn’t work...radio is fine, dash is fine....and the car won’t even crank in the slightest, like some electrical is wrong more than a flat battery.

[GreenV8S]

If the charger was connected across the battery then it's unlikely that anything you have done caused the problem. More likely that you have a blown fuse, failed relay etc causing the other problems. An auto electrician ought to be able to track that down if you don't fancy trying to diagnose it yourself.

[finlo]

Some vehicles have a large inline fuse on the battery lead that can blow leaving other minor circuits live.

[E-bmw]

GreenV8S said:

If the charger was connected across the battery then it's unlikely that anything you have done caused the problem. More likely that you have a blown fuse, failed relay etc causing the other problems. An auto electrician ought to be able to track that down if you don't fancy trying to diagnose it yourself.

^^^^ Wot 'e said.

[itz_baseline]

Turns out it was the AAM module that I blew. Now all replaced and car running find again.

[GreenV8S]

itz_baseline said:

Turns out it was the AAM module that I blew. Now all replaced and car running find again.

Any idea whether this was caused by something you did? Starting the car with a charger connected across the battery could have blown a fuse in the charger but seems unlikely to damage anything on the car.

[itz_baseline]

GreenV8S said:

Any idea whether this was caused by something you did? Starting the car with a charger connected across the battery could have blown a fuse in the charger but seems unlikely to damage anything on the car.

Couldn’t say for sure. It could be coincidence but given everything was fine (although a weak turn over) before I connected it, it would suggest it is linked.

Lesson learned, disconnect chargers from the mains before trying to start the car. Better this than risk.