[DenimDan]

I have a 2006 325i with 130k miles. I recently changed the battery, IBS, and starter (less than a year old). Yesterday evening, I put in the key and press start as I normally do - No crank, Dash lights illuminate, seat adjusts, radio is on, etc.. So I started my checklist.

1. Tried other key with same results
2. Was able to change gears with Brake pedal pressed (sensor okay)
3. Battery is charged at 12.33v
4. Terminal B+ charge is also 12.33v

My next step was to check the BST on the positive battery cable. I disconnected the battery however, i wasn't quite willing to break apart the casing surrounding the BST because I'm not certain that's the issue and don't want to risk it discharging. When I reattached my battery viola, the car turned on. It also started the next day.

Any ideas? I have a code reader on the way to try and get some more information. I'm really hoping the starter didn't go out again because it's less than a year old.

Thanks

[W37V]

Since you have power and the only thing you can't do is turn over the engine, I would say it is starter. Check fuses first. Also, on e9x cars, ground cable (one under the car and second by the exhaust side of engine) tend to go bad and break. That might cause you to have some electrical gremlins.

[gbalthrop]

Originally Posted by DenimDan

...2006 325i with 130k miles...No crank, Dash lights illuminate, seat adjusts, radio is on...I have a code reader on the way to try and get some more information. I'm really hoping the starter didn't go out again because it's less than a year old. Thanks

The issue would seem to be related to CAS Module Activation of the Starter, or with a bad Battery Cable Connection or Ground Connection, that intermittently prevented flow of sufficient Amps of current to crank Starter, even if activated by CAS. Here is the CAS (A149a) & Starter (M6510a) circuit for your 2006 325i:
https://www.newtis.info/tisv2/a/en/e...system/r14Nexa

When you get the Scan Tool you ordered, please let us know what codes are saved in Memory of any Module that Scan Tool can connect to. ANY generic P-code reader can read MOST codes saved in the DME (Engine Control Module), but there MAY be one or more codes in the CAS Module which a generic Scan Tool cannot connect to.

BTW, the BST is NOT your problem. If that had "blown" (VERY RARE) you would have NO voltage at the Jumpstart Terminal (Red plastic cover next to Washer Reservoir Filler Cover). I presume that Jumpstart terminal is what you are describing as B+ -- technically ANY Voltage Supply from the Positive Terminal of the Battery is "B+". When that "blows" it will NOT reconnect like a loose connection elsewhere in the Voltage Supply to the Starter.

Simple, cheap, thing YOU can do NOW is check that both Battery terminals are tight, Negative battery terminal to chassis connection behind battery is tight, Large ground strap on left side of engine is intact and tightly connected at Chassis and Engine Block connections. If issue recurs, do TWO quick tests:

1) Attach jumper cable as a supplemental Chassis-to-Engine ground strap by connecting one clip to Hex-stud Chassis ground at the right wing/ fender, and the other clip to a good metal point on the engine block, such as a large bolt head. If the engine ground strap is bad/ loose, the Starter will NOW CRANK.

2) If nothing changed after attaching cable per (1) above, have a helper test for voltage at the Jumpstart terminals, and see how much that voltage drops when you press START with foot on Brake Pedal.

That test #2 is to check for possible corroded "Transfer Point" where B+ from Battery passes through the chassis just ahead of the Battery.

Please let us know what you find,
George