I have a 2001 Bmw 740i and I just replaced the battery and now the car will turn over but won't start and the alarm randomly goes off

Fuseable link close to battery check

it needs to be plugged in and coded im afraid.. the fact battery changed they tend to do various non funny things.. so full diagnostic and get rid of all history then do diag again for fresh faults...

check the negative wire from the battery to the body (not good ground ) clean

Disconnect the battery, have the ignition key turned to the "on" position then reconnect the battery.

Hi.

If it does turn over and electrical works, then the problem is unlikely the battery. You can try jump starting. If it cranks when jump-starting it may be a weak battery, starter motor or alternator, but I don't think that this is the problem.

Check if there is spark on all cylinders. Do a code scanning (this car is OBD1, you will need to do the scan at the dealer place or to find a BMW OBD1 tool- Universal OBD2 scanner will not work on a 1994 BMW). If the codes return misfire or mixture related errors check fuel pressure, check sensors and parts that determine the mixture (MAF/MAP, AIT, O2 sensors, IAC and EGR system), check the vacuum system for leaks and check the crank sensor.

Regards.

Ginko

I think it's an alarm problem, make sure the alarm is disabled.

well if i remember this alarm has its own back up battery they can couse this isues but if your regular battery is losing power this will do it some time the car may not be going to sleep as we call it battery gose low alarm gose of you may have drain going on or bad secondary battery hope this helps

Take the negative battery cable off overnight. This should fix it it.

I had a similar problem, 2003 530i, but only while the alarm was active. The culprit was a bad hood switch that was making intermitent connection.

there should be a sensetivity nob on the alarm box itself turn that down and your problem should be solved if not just invest in a new alarm.