[Boswelbr]

I have a 2014 F31 with Harman/Kardon sound. Recently, I have been completely losing audio when the engine comes on. Audio works when car is in park or when the engine shuts off due to On/Off feature at stop lights. I have lost audio similar to this in the past, but the problem would not persist.

This issue has persisted for a few days now. To troubleshoot, I attempted to solve the problem by unplugging the battery for a few minutes. Unfortunately, this did not solve the problem.

Any thoughts or similar experiences? I can add a video of the issue if need. Thanks in advance!

[Encanto]

Sounds (pun intended) to me that your battery either is bad or not getting charged properly/enough -battery is only charged under certain driving conditions. Less probably but possible nonetheless is that your OEM amp is defective or the MOST fiber signal is reacting to something failing when engine is turned on.

Originally Posted by Boswelbr

I have a 2014 F31 with Harman/Kardon sound. Recently, I have been completely losing audio when the engine comes on. Audio works when car is in park or when the engine shuts off due to On/Off feature at stop lights. I have lost audio similar to this in the past, but the problem would not persist.

This issue has persisted for a few days now. To troubleshoot, I attempted to solve the problem by unplugging the battery for a few minutes. Unfortunately, this did not solve the problem.

Any thoughts or similar experiences? I can add a video of the issue if need. Thanks in advance!

[Boswelbr]

Originally Posted by Encanto

Sounds (pun intended) to me that your battery either is bad or not getting charged properly/enough -battery is only charged under certain driving conditions. Less probably but possible nonetheless is that your OEM amp is defective or the MOST fiber signal is reacting to something failing when engine is turned on.

Is there a way to test battery health or just replace it and hope for the best? I did see the battery had a manufacturing date of early 2013 so it's nearing its lifespan.

[Billfitz]

If it was the battery you'd be seeing many issues, mainly the warning on your dashboard display that the battery isn't full charged. Also, if the battery was weak it wouldn't turn the radio on when the car is off at a stop light, because that's when the alternator isn't providing power and the drain on the battery is high. With a weak battery the car wouldn't shut off at lights at all. You need to get your fault codes read.

[Boswelbr]

I have a minor update. On the way home yesterday, the radio randomly began working again after 30 minutes of driving. Audio worked the rest of the ride until I turned the car off. This morning, I turned on the car and the audio problem was back. Any thoughts?

[Billfitz]

OK, so what happens when the engine is running but not when it's off? Vibration. That leads me to think a loose connection somewhere. Coming back on intermittently also points to a loose connection.

[Boswelbr]

Will a loose connection trigger an error code if I check it via OBD?

[Billfitz]

It might. Since the age of your car indicates that a battery is in your future it wouldn't hurt to get a Foxwell NT510, which will register your new battery when that day comes, and might diagnose the problem with your radio. BTW, does just the sound kick out? What about the dash readout? Does it show the radio is working? The former may indicate an amp problem, the latter a head unit problem.

[Boswelbr]

From what I've noticed, the only thing I lose is audio. They head unit displays it is still playing the radio. I have tried switching to Bluetooth, CD, etc. and the problem persists.

To start checking for loose connections, should I remove the head unit and start there or is there a better place to start?

[Billfitz]

If the head unit says it's playing I'd check the connections to the amp, which is located in the trunk. It could be the cable coming out of the head unit, but more likely those going into and out of the amp.

[Boswelbr]

Changed the battery but didn’t have the tool to register it yet. Did not solve the problem. I will update in a couple of nights when the tool to register it comes in.

Unplugged and re-plugged connections to the amp, no luck there either. If registering the battery doesn’t help, I’ll try connections behind the head unit. Anyone other ideas, anyone?

[Billfitz]

Registering the battery won't affect the radio, it's only necessary so that the charging system knows that it's new and charges it accordingly.

[Encanto]

You need two people for this

- open trunk
- leave it open for 10 minutes or so
- unplug MOST connector from trunk
- it should have no light coming out, if it does wait until it goes off
- open driver’s door while the other person is looking at the MOST connector; light should turn on
- turn engine on; light should stay on
- if light turns off then there is a MOST problem; MOST turns OEM amp on/off.
- note that the instrument cluster also uses MOST for the extended display. If the display is ok then MOST ring (iDrive -> cluster -> OEM amp -> iDrive) shall be ok as well. If cluster is ok then you should see the light at the OEM amp connector. Otherwise the problem is at the iDrive unit.
- else, plug MOST connector back into OEM amp; OEM amp should turn on
- if OEM amp does not turn on/no audio with MOST light on then problem may be the OEM amp

[Boswelbr]

Originally Posted by Billfitz

Registering the battery won't affect the radio, it's only necessary so that the charging system knows that it's new and charges it accordingly.

I figured it will have no effect, but thought it may reset something. I realize I'm grasping at straws here, but it's been pretty frustrating.

[Billfitz]

I don't think there's anything in the car that doesn't have at least one sensor, so there's a good chance you'll find a fault code once you get your reader.

[Boswelbr]

Pulled the attached codes. Couldn’t find much help on Google. Any thoughts about these?

[Boswelbr]

Added fault codes in body of post rather than the attachment. Anyone think one of this would affect audio? Thanks!

BASE: F30
BUILD-YEAR: 2014
MODEL: 3 (F30, F31, F34, F35) alle/all (991)
ADDITIONAL OBD: OFF
FAULTS: 19
ECUs: 24
BATTERY: 14.5V
DEPTH: Enhanced communication
SPEED: slow
CONNECT: (null)
VERSION: 11.2.5
WIFI: >Carly Adapter v00<
ELM: >ELM327 v1.4 v21<
COM+: >YES<
<===========================>
0. Motor Control:
<--------------------------->
Engine / Motor:
ECU OK, no fault code
<===========================>
1. ABS / DSC / Brake:
<--------------------------->
Dynamische Stabilitäts Control / DSC:
ECU OK, no fault code
<===========================>
2. Heating / AC:
<--------------------------->
Air conditioning / Klimaanlage:
- Fault: Power Management: Reducing fan horsepower
- Code: 801228
- Fault: K-CAN message (STAT FUNKSCHLUESSEL, 0x23A, FA): OP KEY BUT SPFn invalid signal
- Code: E7146F
<===========================>
3. Immobilizer System:
<--------------------------->
Body Domain Controler :
- Fault: :Welcome light-repeat active
- Code: 8041A8
- Fault: Signal from the rain light sensor implausible
- Code: 8041BF
- Fault: Rear View Mirror: Missing LIN slave
- Code: D90D26
- Fault: RLS (LIN slave): Missing LIN slave
- Code: D90D29
- Fault: UGDO: Missing LIN slave
- Code: D90D2C
<===========================>
4. Cruise Control:
<--------------------------->
Active cruise control / Aktive Geschwindigkeitsregelung:
- ECU not present/no answer
<===========================>
5. Audio / Navigation / Communication:
<--------------------------->
Infotainment:
- Fault: :KISU Application Error
- Code: B7F85F
<===========================>
6. Systems:
<--------------------------->
Front Electronic Module / Elektronik Modul Vorne:
- ECU not present/no answer
<===========================>
7. Chassis:
<--------------------------->
Steering /Lenkung:
- Fault: Sensor - rotor position - steering angle - loss multiturn value
- Code: 482394
<--------------------------->
Electronic damper / Elektronische Daempfer:
- ECU not present/no answer
<===========================>
8. Body:
<--------------------------->
Automatisches Front Steering:
- ECU not present/no answer
<--------------------------->
Rear Electronics Module / Elektronik Modul hinten:
- Fault: ZV drive tailgate (MERHK): defective contact tailgate
- Code: 804840
<--------------------------->
Integrated Chassis Management Quer/Längsdynamik:
- Fault: SBS function - direction unsure vx greater than 2 m / s
- Code: 480134
- Fault: Signal fault (actual position EPS, ID: AVL PO EPS) - Qualifier
- Code: D014A1
<===========================>
9. Motor Control:
<--------------------------->
Advanced Crash and Safety Management (ACSM):
ECU OK, no fault code
<--------------------------->
Bordcomputer BC4 E32 / E34:
ECU OK, no fault code
<--------------------------->
Central Gateway / zentrales Gateway:
- Fault: :Synchronization process failed, CC was not in sync with the date of repeal of error Memory Lock / FLEXRAY StartUpFailed
- Code: CD0487
- Fault: emand reset terminal 30F Alarm Clock / Request state ParkenBN NOK Alarm Clock
- Code: 801C10
- Fault: :Request shutdown terminal 30F Alarm Clock
- Code: 801C11
- Fault: :Faulty asleep at 30B
- Code: 801C15
<--------------------------->
Fuelpump-Modul (E6/PL2):
ECU OK, no fault code
<--------------------------->
Getriebesteuerung /Transmission:
ECU OK, no fault code
<--------------------------->
Reifendruck System:
ECU OK, no fault code
<--------------------------->
Speech recognition / Spracherkennungs-system:
ECU OK, no fault code
<--------------------------->
Hifi Amplifier / Verstaerker:
ECU OK, no fault code
<--------------------------->
Active Sound Design M5:
ECU OK, no fault code
<--------------------------->
Anti-Blockier-und Stability Control 5 auto. E34 / 16:
ECU OK, no fault code
<--------------------------->
Gear switch / Gangschalter:
ECU OK, no fault code
<--------------------------->
Instrument cluster / Kombiinstrument:
- Fault: :Information: terminal 30f has been switched off (terminal 30 error-off delay time controlled 0x3AC)
- Code: E12C1D
- Fault: :COMBI: System time has been reset
- Code: B7F668
- Fault: :EGS interface (data display gear train 0x3FD); invalid signal
- Code: E114BE
<--------------------------->
Advanced Telematic Module:
ECU OK, no fault code
<--------------------------->
Central Control / Zentrale Bedieneinheit:
ECU OK, no fault code
<--------------------------->
Driver seat /Sitz Fahrer Heck:
ECU OK, no fault code
<--------------------------->
HiFi:
ECU OK, no fault code

[jgoens]

That KISU error is suspicious. I would Google that and try to see what that is about.

[Boswelbr]

Originally Posted by jgoens

That KISU error is suspicious. I would Google that and try to see what that is about.

Can't find anything on the KISU error (or much on KISU in general). During my troubleshooting, I was going to try to update iDrive software. However, my car is on MN-003.003.001 while the latest avilable online is MN-002... number. Any ideas?

[Boswelbr]

Update: I caved and took the vehicle to the dealer. They claim there was a "gooey not water substance" on top of the amplifier. This seems odd because I believe I would've noticed a large spill in the trunk. It's also odd to me that a bad amplifier would cause an intermittent issue. They quoted $2,361 for the new amplifier and replacement.

As a fun side note, they inspected the car and found what they believe to be pothole damage. Leaking front strut, leaking control arm bushing, and 3 bent wheels. Always fun to go to the dealer! $6,000 for all repairs including the amp was my quote.

[Billfitz]

Originally Posted by Boswelbr

They quoted $2,361 for the new amplifier and replacement.

Absurd. I'd get one out of a wreck. You already know what it takes to install it.

[Boswelbr]

Originally Posted by Billfitz

Absurd. I'd get one out of a wreck. You already know what it takes to install it.

Trying to find a used one is the plan. Having the HK system is making it a huge pain.