Electrical Gremlin

DrC_UArk · 07-22-2016, 09:45 AM

2007 335xi, auto, 40k miles.

How this for odd? - Recent electrical gremlin has presented itself. The stereo (logic 7) only works with the headlights on. When the headlights turn off (either fully off, or off in auto-mode) the stereo switches to "phone connect" mode and loses all other function.

Just before this began, the radio started to develop static on local fm stations that normally have perfect reception. I'm unsure if this is related, but it could be a symptom.

Fuses check out. No codes.

Anybody encountered this?

patents · 07-22-2016, 11:50 AM

Hello fellow Razorback.

This is very odd. How's the battery? Age? Failing batteries can cause a lot of very strange things. Other than that, I would suspect a failing in-dash audio unit. Do you have iDrive?

DrC_UArk · 07-22-2016, 12:47 PM

No iDrive. Battery was replaced in Nov 2012, so is less than 4 years and 7k miles old. My battery tester shows full voltage.

BayMoWe335 · 07-22-2016, 01:50 PM

I'd replace the battery anyway. 4 years isn't necessarily old, but it's not new. Make sure you get an OEM one too. Cheapest place to start even though it's not cheap.

DrC_UArk · 07-22-2016, 03:46 PM

Noted. Though a diagnosis of some kind is preferable to replacing untested parts. A full battery test seems a prudent choice.

ctuna · 07-22-2016, 05:16 PM

And or you could put a full charge on it.

patents · 07-22-2016, 06:20 PM

You only drove 7k miles in 4 years? Wow.

What's the voltage reading on the battery?

DrC_UArk · 07-23-2016, 10:06 AM

13.6 volts as it sits.

Previous owner didn't drive much, only weekends etc. I acquired the car in January with 36k on it. It now has 41k.

In response to the "fully charge it" suggestion, just Tuesday of this week I drove the car 230 highway miles. That should have fully charged the battery, yes? Unless the alternator is faulty, for which there are no apparent signs.

patents · 07-23-2016, 02:35 PM

Sounds like the battery is fine.

Not exactly sure how to go about diagnosing the various components of the radio/communication system.

There may be a chance that there's a diagnostic code set, but with this type of problem I wouldn't count on it.

Your last resort would be to get the dealer to diagnose it, but don't let them replace the parts, it will be too expensive. You can get the components used a lot cheaper and put them in yourself.

07-22-2016, 09:45 AM	#1
DrC_UArk Private 23 Rep 61 Posts Drives: '07 335xi Join Date: Jan 2016 Location: Fayetteville, AR iTrader: (0)	Electrical Gremlin - Headlights vs Stereo 2007 335xi, auto, 40k miles. How this for odd? - Recent electrical gremlin has presented itself. The stereo (logic 7) only works with the headlights on. When the headlights turn off (either fully off, or off in auto-mode) the stereo switches to "phone connect" mode and loses all other function. Just before this began, the radio started to develop static on local fm stations that normally have perfect reception. I'm unsure if this is related, but it could be a symptom. Fuses check out. No codes. Anybody encountered this?
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07-22-2016, 11:50 AM	#2
patents Lieutenant 164 Rep 598 Posts Drives: 2008 328i Join Date: Aug 2014 Location: Memphis, TN iTrader: (0)	Hello fellow Razorback. This is very odd. How's the battery? Age? Failing batteries can cause a lot of very strange things. Other than that, I would suspect a failing in-dash audio unit. Do you have iDrive?
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07-22-2016, 12:47 PM	#3
DrC_UArk Private 23 Rep 61 Posts Drives: '07 335xi Join Date: Jan 2016 Location: Fayetteville, AR iTrader: (0)	No iDrive. Battery was replaced in Nov 2012, so is less than 4 years and 7k miles old. My battery tester shows full voltage.
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07-22-2016, 01:50 PM	#4
BayMoWe335 Colonel 1176 Rep 2,132 Posts Drives: 2010 E92 335i 6MT Join Date: Aug 2009 Location: US iTrader: (0)	I'd replace the battery anyway. 4 years isn't necessarily old, but it's not new. Make sure you get an OEM one too. Cheapest place to start even though it's not cheap.
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07-22-2016, 03:46 PM	#5
DrC_UArk Private 23 Rep 61 Posts Drives: '07 335xi Join Date: Jan 2016 Location: Fayetteville, AR iTrader: (0)	Noted. Though a diagnosis of some kind is preferable to replacing untested parts. A full battery test seems a prudent choice.
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07-22-2016, 05:16 PM	#6
ctuna Lieutenant General 1911 Rep 13,103 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	And or you could put a full charge on it. And or you could put a full charge on it.
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07-22-2016, 06:20 PM	#7
patents Lieutenant 164 Rep 598 Posts Drives: 2008 328i Join Date: Aug 2014 Location: Memphis, TN iTrader: (0)	You only drove 7k miles in 4 years? Wow. What's the voltage reading on the battery?
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07-23-2016, 10:06 AM	#8
DrC_UArk Private 23 Rep 61 Posts Drives: '07 335xi Join Date: Jan 2016 Location: Fayetteville, AR iTrader: (0)	13.6 volts as it sits. Previous owner didn't drive much, only weekends etc. I acquired the car in January with 36k on it. It now has 41k. In response to the "fully charge it" suggestion, just Tuesday of this week I drove the car 230 highway miles. That should have fully charged the battery, yes? Unless the alternator is faulty, for which there are no apparent signs.
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07-23-2016, 02:35 PM	#9
patents Lieutenant 164 Rep 598 Posts Drives: 2008 328i Join Date: Aug 2014 Location: Memphis, TN iTrader: (0)	Sounds like the battery is fine. Not exactly sure how to go about diagnosing the various components of the radio/communication system. There may be a chance that there's a diagnostic code set, but with this type of problem I wouldn't count on it. Your last resort would be to get the dealer to diagnose it, but don't let them replace the parts, it will be too expensive. You can get the components used a lot cheaper and put them in yourself.
	Appreciate 0 Quote