[LeakyM3]

Hello everyone! Through lurking you have been helping me for years, but I'm finally stuck.

My 2012 335i will not crank. It all started when I got news that my Tacoma was finally on it's way to the dealership after an 8 month wait. My car started being slow to start, then a few days later all I got was a click. Luckily it's a manual, and push starting still worked, so I didn't need a tow home.

My first assumption was a weak battery as it's 4 years old, but it tested good. Second assumption was the starter so I replaced it with a reman unit from my local auto parts store. It worked 6-8 times and then, click! I exchanged it even though it worked on their bench test. The second starter worked exactly 3 times before all I got was a click.

I tried using jumper cables to ground the engine to the ground post with no luck. Dug through everything I had touched to make sure I didn't miss any connections. Then started looking for a laptop to borrow for INPA. Please help!
Note: I have jumper cables on while taking these

[LeakyM3]

Turns out I didn't follow directions... probably how I ended up in this situation.

[gbalthrop]

Originally Posted by LeakyM3

2012 335i will not crank... [battery] tested good. Second assumption was the starter so I replaced it with a reman unit from my local auto parts store. It worked 6-8 times and then, click! I exchanged it even though it worked on their bench test. The second starter worked exactly 3 times before all I got was a click. I tried using jumper cables to ground the engine to the ground post with no luck...

Your description, and your INPA ScreenPrints, suggest that you have an intermittent failure at a connector or wiring between the CAS Module and the Starter Solenoid. NOT sure whether the failure mode is (1) Open Circuit, or (2) Short to Ground.

1) Your CAS Terminal Control Digital Screen shows BOTH Gear PN (Neutral shift lever position) and Clutch Depressed, BOTH of which are required on MT BEFORE CAS will send Terminal 50 Start Signal to Starter solenoid.

2) Your CAS Diagnose Terminals Analog Screen shows KL50 (Terminal 50 Start Signal) voltage of 11.31V, while KL30E (Power supply to CAS Electronics) = 12.34V. If Starter were Cranking engine, you would have a voltage drop of ~ 2 volts, and that value would be in 10.3V range. So CAS is sending Start Signal (KL50) to Activate Starter Solenoid. Apparently "Sometimes" that signal is NOT getting to Starter Solenoid.

That suggests testing for BOTH open circuit AND Short-to-Ground in the Black "S_50" Start Signal wire between CAS Module & Starter Solenoid, particularly examining the two intermediate connectors, X6011/1 & X60531 in the E-box. See the ISTA ScreenPrints, attached to NEXT Post, for CAS circuit, and Connector Location.

Note that there is NO Documentation of the Existence or Location of the X60531 connector on your 2012 N55 model. I do attach a "Connector View" for a connector with that "Label". On other models, that connector is located on inboard side of E-box, connecting to wiring EXITING the Ebox to the Engine Compartment. Just follow the Black wire from X6011/1 and see where it goes.

I'm NOT sure WHAT is going on with the KL50L CURRENT (AMPS). If that value of "!63.97" Amps is accurate, there is a SHORT in the 'S_50' Black KL50 Signal wire somewhere between CAS & Starter. My N52KP 328xi shows ~ 10 Amps KL50 Current during correct Starter Cranking, along with KL50L Voltage in 10.5V Range (2 Volt Voltage Drop).

Hope you have a DMM (Digital Multimeter). If NOT, the cheapest $7 HFT or $10 Amazon meters work fine for E9x diagnostics. Please let us know what you find, or if you have any questions on Test methods or values.
George

[gbalthrop]

Attached are 3 ISTA ScreenPrints related to prior post, showing KL50 Start Signal wiring & Intermediate Connectors.
George

[LeakyM3]

I thought that amp value looked suspicious. I broke out my multi meter and circuit tracer to track this problem down. I get a continuity signal with a resistance of 0.4 Ohm from the X6011/1 pin to the starter solenoid connection, and the circuit tracer seemed to suggest no other wires in the loom were receiving the signal. I have removing the intake manifold down to an art at this point, so it's off again.
Jumping 12 volts to X6011/1 results in the same click as pushing the start button. Jumping straight to the starter solenoid does as well. I currently have a jumper cable as shown to the negative terminal of my battery in the trunk. Jumping straight to the solenoid results in the same click!

[LeakyM3]

I spent a while ignoring the car and didn't have the motivation to work on it while it was freezing outside, but I think I found my problem last night!
With a jumper cable running from the positive jump terminal to the power supply of the starter the car cranks. This narrows it down to the alternator-starter-base B+ cable.

[rick_flying_machine]

Hi LeakyM3

I have the exact same issue on my N55 with the KL50L amp overload. Have you confirmed that the alternator-starter cable was you issue?