'96 M44 - Doesn't crank over

[PixelRandy]

1996 318ti M44

Hi - I tried searching for a solution first, but there are so many no-start threads that it's mind boggling.

My car started and ran fine before I took it apart and rebuilt the cooling system. While I was in there I also replaced the starter with a re-manufactured Bosch unit.

Bolted everything back together, double-checking each connector to make sure they were seated, etc.

Anways, I completed the job this afternoon. Turn the ign switch on and the dash lights up normally. Turn to "start" and I hear a relay up front click on, but that car doesn't crank over. It's a three month old battery, checked for voltage and topped it off. Same problem. Climbed under the car, double-checked the connection to the starter. All three wires are connected.

While digging around for a solution, someone mentioned you shouldn't disconnect the battery with the key in the switch as it can activate the immobiliser. True? I did disconnect the battery with the key in the ignition if that matters.

Am I missing something really obvious?

Any bones you can throw would be really appreciated.

Cheers,

Randy