u/Antoniomike7

Hi all,

Looking for some help with a really strange intermittent no crank issue on my 2007 BMW E87 116i.

The car powers on completely normally:

• Ignition comes on
• Dash stays lit
• Fuel pump primes
• But pressing the start button usually does absolutely nothing

Sometimes there’s a delayed click from the engine bay a couple seconds later.

Fault codes originally were:

• A0B4
• A0C1
• A0C2
• 2E1C

What I’ve replaced so far:

• Starter motor
• Engine-to-chassis earth strap underneath passenger side
• KL30G relay in glovebox

Battery has been charged/tested but not replaced.

Interesting part:
After charging the battery, the car became intermittent instead of fully dead:

• Sometimes I’d have to press the start button multiple times
• Eventually it would crank and start
• Crank sounded sluggish / lower pitch than normal

Then it went back to full no crank again.

Diagnostics so far:

• ISTA/INPA show Terminal 50 active
• Starter request appears active
• Previously saw ~0.41A on KL50L during start attempts
• Voltage hovers around 11.8V
• Booster pack doesn’t seem to change much

Latest INPA readings:
Before pressing start:

• KL50RS = 0V
• KL50L current = 0A

Immediately after pressing start:

• KL50RS jumps to ~11.8V
• KL50L voltage rises to ~11.8V
• HALL12/HALL34 rise to ~11.18V
• Still no crank whatsoever

Current CAS faults:

• A0B4
• D904

A couple more notes:

• Early E87 without IBS fitted
• CAS recognises key normally
• Ignition behaves completely normally
• Dash doesn’t dim heavily during attempts

At this point I’m leaning toward:

• Main positive cable resistance
• Bad battery/chassis connection
• Voltage drop under load
• Bad connection at starter
• Faulty replacement starter
• CAS power supply issue maybe?

Has anyone seen an E87 behave like this where it occasionally starts after charging/reconnecting battery, then immediately goes back to no crank?

Would really appreciate any ideas because I feel like I’m close but chasing my tail now.