Car Intermittently Wont Start

[BRNDNSLVRA]

I changed my starter about 2 weeks ago and since then Ive been having a weird issue. Sometimes when I go to start the car (mainly at night) nothing happens except the hazard button just flashes sporadically. Heres the strange part. I either wait it out or I drop my rear seats to access the emergency trunk latch to reset the battery.

However, I dont even need to open the trunk. Sometimes the release cable wont even open the trunk. It might be worn or something. But if I move the cover that hides the battery, everything works and I can start the car. Just touching it has worked sometimes. Sometimes trying the latch works. Ive looked at the battery and checked connections. Everythings fine so I dont know what the hell is causing this weird issue.

Anybody have an idea? Car doesnt have any codes that point to it. Just EDC code, TPMS error and brake pad warning (wear sensor loose). But those are all old.

Update: Feb 13

So a the same day I posted this, I went and just got a new negative terminal t-bolt and locked it down. Havent had the issue since so I guess that was the issue. I feel stupid but not really cause when I was having CAS issues, I would keep the cable loose to easily reset the battery and the car never gave me issues w/ starting unless the CAS was acting up.

But anyways, everything is all good. Appreciate you guys for helping. Love this community.

[tdott]

Have you done the positive battery cable recall?

Could also be a grounding issue.

[BRNDNSLVRA]

Originally Posted by tdott

Have you done the positive battery cable recall?

Could also be a grounding issue.

Yeah I did it a while ago. The t-bolt for the negative cable was a little loose. I reseated it and got it to stay tight. Maybe that was the issue. Dont see how moving the cover would make things work againz Its really strange.

[RocketyMan]

Had the same issue with a buddies M3, and he replaced the starter--seemed to help, but same issue. Turned out, his FRM had an issue too. Once he got the FRM rebuilt, it started more consistently.

Have you done anything with your FRM? Any fault codes?

[BRNDNSLVRA]

Originally Posted by RocketyMan

Had the same issue with a buddies M3, and he replaced the starter—seemed to help, but same issue. Turned out, his FRM had an issue too. Once he got the FRM rebuilt, it started more consistently.

Have you done anything with your FRM? Any fault codes?

These are all the code I have now. No clue what the steering angle thing is about.

[RocketyMan]

I think the scan can happen if the ignition isn't turned on "fully." I've had that happen before where the DSC was not reporting on the network. So to me, non-issue as I imagine if the car is actually running you don't have ABS codes or the like.

[DrFerry]

Originally Posted by 954MM

I changed my starter about 2 weeks ago and since then Ive been having a weird issue. Sometimes when I go to start the car (mainly at night) nothing happens except the hazard button just flashes sporadically. Heres the strange part. I either wait it out or I drop my rear seats to access the emergency trunk latch to reset the battery.

However, I dont even need to open the trunk. Sometimes the release cable wont even open the trunk. It might be worn or something. But if I move the cover that hides the battery, everything works and I can start the car. Just touching it has worked sometimes. Sometimes trying the latch works. Ive looked at the battery and checked connections. Everythings fine so I dont know what the hell is causing this weird issue.

Anybody have an idea? Car doesnt have any codes that point to it. Just EDC code, TPMS error and brake pad warning (wear sensor loose). But those are all old.

My money for the root cause is a loosely connected or bad IBS..
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One important item to check with these symptoms is the "Intelligent Battery Sensor".....
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The IBS contains a micro-processor that is used to monitor/measure various battery conditions such as:

Terminal voltage via measurement from B+ to Gnd
Charge/discharge current via integrated shunt resistor
Temperature of battery acid via integrated temp sensor

And


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IF the sensor (blue plastic plug) is not clicked back together after battery replacement, then gremlins they WILL be comin'.. It's definitely worth checking..

https://bimmerscan.com/bmw-intellige...ry-sensor-ibs/

BMW Intelligent Battery Sensor (IBS)
The BMW Intelligent Battery Sensor (IBS) is a mechanical/electronic device which is connected directly to the negative battery terminal. The measuring/evaluation function of the IBS electronics, continuously measures the following values under all vehicle operating conditions:

Voltage (6V to 16.5V)
Current (200A to +200A)
Closed Circuit Current (0A to 10A)
Starting Current (0A to 1000A)
Temperature (-40C to 105C)
When the vehicle is stationary, the IBS is programmed to wake up every 14 sec. and makes the required measurements within approx. 50 ms in order to save power. The measured values from the IBS are provided to the DME by way of the Binary Serial Data Interface (BSD) to calculate the State of Charge and State of Health for the battery.

State of Charge (SoC) is a calculated condition showing the current charge of the battery. SoC is used during key ”OFF” periods to insure the battery maintains a sufficient charge to start the engine at least one more time.
State of Health (SoH) tracks the history of the battery. Charge/dis-charge cycles and times are monitored. SoH helps the DME determine the proper charging rates and anticipated battery life. Internal resistance of the battery is calculated by the IBS from the current and voltage dip during engine start. The values are forwarded to the DME to calculate the SoH of the battery.

Software contained in the microprocessor of the IBS utilizes the measured values to calculate the State of Charge (SoC) of the battery during vehicle sleep mode and compares this information with that received from the DME/ECM pertaining to the battery SoC/SoH, during the period of time between engine “OFF” and deactivation of the DME main relay.

The current SoC/battery data is stored in the IBS every 2 hours over a 6 hour time frame, providing 3-2 hour snapshots of battery SoC information. The stored information/snap-shot data is overwritten every 6 hours. Whenever KL15 is activated the IBS updates the DME with the current closed circuit histogram/battery status information, by way of the BSD. Upon obtaining updated information the DME evaluates the new data and if a closed-circuit current draw is identified a fault will be stored in the fault memory of the DME.

IBS Diagnosis
A fault code is stored in the DME when the IBS is defective. The DME adopts a substitute value and assumes IBS emergency mode. IBS emergency mode boosts the idle speed in order to sufficiently charge the battery. Direct diagnosis of the IBS is not possible, it can only be diagnosed through the DME. The self-diagnosis function checks the voltage, current, temperature, terminal 15 wake up signal as well as system errors in the IBS.

Diagnosis Hints

AND

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The DSC code you're getting is for one of the brake pad sensors which is also loose or gone bad.

[Redd]

A loose IBS may cause battery charging issues but won't stop the car from starting. You can run perfectly fine without the IBS without any errors (except for weird battery charging).

[DrFerry]

Originally Posted by Redd

A loose IBS may cause battery charging issues but won't stop the car from starting. You can run perfectly fine without the IBS without any errors (except for weird battery charging).

The IBS service document I posted above mentioned vehicles exhibiting “No start condition”. So I thought it was worth posting this information again.
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[Scrippy]

I couldn’t start my car out of the blue two weeks ago. I don’t have the error code handy but it was the “terminal 50” error. Let it sit for some hours and tried again with no luck. Removed all connections from battery & IBS. Put it all back and still no start. Two days later when my neighbors showed up to help me push the car in the garage it fucking started. Been two weeks and no other issues or errors present. My point is maybe when the shop was painting my bumper just before this event they removed the battery and one of the cables wasn’t seated properly when put back? Keeping an eye on it but I replaced nothing. Maybe check all battery connections thoroughly before chasing things.

[RocketyMan]

Originally Posted by Redd

A loose IBS may cause battery charging issues but won't stop the car from starting. You can run perfectly fine without the IBS without any errors (except for weird battery charging).

Agreed.

Originally Posted by DrFerry

The IBS service document I posted above mentioned vehicles exhibiting “No start condition”. So I thought it was worth posting this information again.
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This would be by means of a dead battery, then yes, start conditions. Look at the condition before stating "battery discharge." Actually all of those relating to a compromised battery effectively by a poorly charged battery.

At any rate, still very useful information you posted! And I think the OP should def check it out!...So OP....have you checked ALL of the battery connections?