Cabin fan/heated seats

[cla67]

Ok, this one has me stumped...
Within the last 2 months I have noticed my blower motor will stop working about 30 seconds after the car is started. All lights are working fine and the defrost setting will work ok as well. Being that it is winter, I have also found the heated seats and steering wheel also turn off at the same time.

Now the odd thing, after almost 20 min. the fan and seats come on and are fine as long as the engine is on. Never cut out again. If I turn the car off and restart, no matter how long it has been running before, it takes the 20 min. cycle to reset.

I have had a fault code for the ABS system that was diagnosed as and "under voltage" but the fan issue did not coincide with when it appeared.

Are there any resources for electical schematics?

2007 3.0 with 111k. This thing has been killing me for the last 6 months. It's like they built it to fall apart at 100k.

[seattle]

How old is the battery?

[cla67]

only a couple years old. I was having problems with the self leveling suspension. Finally replaced the air struts. Was thinking maybe it caused some excessive battery drain since the pump would have to kick on every time I opened the doors.

Did find a thread where someone mentioned trying to disconnect the negative post for 20 min.

[TerminatorX5]

both the blower and the seats are "heavy consumers" and as a result, if the system detect low power reserves, it will shut off those non-essential "heavy consumers" in effort to preserve the energy for vital systems... once the alternator tops off the battery, the systems come back to life... so, your system operates as designed...

however, you want to know why you have low power reserves... could be failing battery (even spanking brand new batteries off a shelf are known to have issues), could be failing alternator, could be battery not properly being charged as couple of years ago, when it was replaced, it was not coded to the vehicle for proper charginig levels...

[seattle]

All these symptoms point to a bad battery and/or bad alternator. The car would shut down unessential components (seat, wheel heater, but not defroster (safety issue?)). The ABS low voltage may have been the first messenger about coming issues.
The symptoms your vehicle is experiencing are actually mild compared to 4X4, DSC and other that different folks on the forums were experienced due to bad battery.

[seattle]

Lol my post now looks like a bold plagiarized copy of TerminatorX5's..

[TerminatorX5]

Originally Posted by seattle

Lol my post now looks like a bold plagiarized copy of TerminatorX5's..

no worries, your post means that mine is not that much off!!!

measuring the battery with a voltmeter is not the same as measuring the electrical system through the internal circuitry using the designated methods... I am not sure about the E70, but in older E53 one of the cluster tests shows the battery voltage as the car sees it, which can be different from the reading taken directly from the battery...

a 3 year old battery, even from a dealer can be already dying... and the alternator may have a bad or dying diode inside the regulator, which can be shunt, and once warmed up, would open... besides, the current draw, as mentioned earlier, can be different under different circumstances - there could be processes in the car that are running on the background...

battery should be around 12 V when nothing is connected (so, 12.3V is good), and the alternator should spit out at least 13-13.5 V in order to properly charge the battery with sufficient current - if the battery is 12V and the alternator is producing 12.5V, the charging current could be too low to properly charge the battery... so, the alt output should be over 13V (closer to 14V) to charge the battery, and not too high, as 16V will fry the electronics...

well... in other words, keep a close eye to the charging circuitry, and if the car under warranty, have them deal with it, otherwise, start with monitoring the alt, and replacing the battery...

[cla67]

Thanks for the good info. I did have the battery replace at the dealer and coded so that should not be the case.

As to the alternator going bad, wouldn't the fact that the systems come back on indicate that it is working by charging the battery back after driving for some time?

I will check voltage on the battery tonight as it's been sitting for a couple days while I wait for new tires to arrive. I read where it should be at least over 12.4v while running.

[seattle]

Originally Posted by cla67

As to the alternator going bad, wouldn't the fact that the systems come back on indicate that it is working by charging the battery back after driving for some time?

Bad alternator does not mean completely dead. It might not be functioning in the first 20 minutes, therefore the system, sensing lower power because being solely on battery, may turn off those components. Just an idea.

[conedoctor]

When did you have the dealer replace the battery?