Fried ecu?
 

2001 1.8tqm
Ok so the other night I was cleaning out my car and left the rear dome lights on and drained the battery. I had my neighbor come over so I could jump the car and when he hooked the cables up he crossed them and sparks shot up pretty good. Put them on the right way myself and when I tried to start it, it kept cranking and wouldn't turn over. I checked all the fuses and they all seemed to be fine. When I turn the key, all the lights (abs, air bag etc) are on except the cel and I get the 3 loud beeps. Does this mean my ecu is done? Don't know if it could be a relay or not. Hopefully somebody can shed some light before I get another ecu.

Last time this guy helped me work on my car he didn't tighten the axle bolts to the tranny tight enough and they were almost falling out. Should've learned the first time I guess.

Also, is it really true that the 4B0 906 018 M ecu and the 4B0 906 018 CH ecus are interchangeable? (Both 01's)

If the cel dose not light up then its no good sorry.

first recharge the battery. then turn the ignition on for a few minutes and wait for the car to do the throttle adaptation. then try and start the car. normally when the CEL doesnt come on when the ignition is first turned on, that is a bad thing but its not always due to a fried ECU. you can however fry an ECU if you do not jump the car correctly.

do you know what else it could mean besides a bad ECU if the cel doesn't come on when the ignition is turned on?

Disconnecting battery?
 

Ghost, are you suggesting disconnecting the battery then trying again with a fully charged battery?

Lou