Another weird electrical problem...one headlight won't turn off
 

This might be the last straw for me with my X5, but I thought I'd post here bc one (of many) previous problems was solved easily with a member's help. I don't know how this is connected but I'm sure it is in some way...

Sunday night when driving home I had the heat cranked and seat warmers on. It was starting to get hot so I turned the heat down. Next thing I know the temperature was displaying as celsius instead of fahrenheit but seemed to be stuck on low. I have no idea how that happened! I fiddled a bit with it before allowing my passenger to do the same, all to no avail. Was almost home so figured I'd worry about it in the morning, if it didn't reset from having the car off overnight.

This morning it wouldn't start..clicking but that's it. Seems the battery is dead. Didn't have time to deal with it then, but tried to jump it just now. No luck, possibly bc the jump car didn't have enough power to get it going. Figured I'd call AAA bc they got it going for me before. Then I noticed that the driver side running light was on. The switch is off, and key out of the ignition, but it stays on! The only thing I could do to turn it off was to disconnect the battery completely. If I reconnect it just goes back on though!

Any ideas???

The corner lights are supposed to stay on low when you have your turn signal on.

It will drain a battery overnight so likely that was why.

Display changes feom F to C if you hold the trip Odo button when you remove the key (or something similar). (maybe put key in and turn to on with the Odo button pressed)

I've had that happen when I had low battery voltage. Mine was the drivers side high beam.

These cars do weird things when battery voltage gets low including switching to celsius, random gauge issues, lights going on/off, etc. Once you get the battery charged or replaced, make sure to test the alternator voltage. You should generally see over 14v when it's running.

I've had water running from the panaoramic roof running down onto the light module, giving problems like this. Resetting it with the foxwell made the problem disappear

Need your year and model info!

A low charging system will trigger multiple electrical errors as the entire system crashes. Check your starting/Charging system before you go down any path.

How to Check a Starting Charging system 101

Starting & charging systems testing techniques
Here are a few quick tests to determine a battery issue, a charging system issue, or a primary wiring issue.

Skill Level: 2 + (read and follow instructions)
Tools required: Digital Volt Meter (DVM), battery terminal cleaning tool, and 8mm, 10 mm sockets and ratchet with extensions.

You need to read battery voltage before starting any test on an electrical system as it will influence the results of Starting, Charging, and electrical tests of any kind. (Note: battery must be fully charged, see chart below).

Step One: Get out a digital volt meter, Read battery voltage (Key off). Read voltage (Key on) at the following points Battery, under hood jump point, and at the alternator. You only need to determine if you have 12 volts at the alternator with the key on (BIG FAT WIRE). A simple handheld digital wave form tester will get you in the ball park when it comes to batteries. (Further discussion on these testers is for another engineering forum).
Step Two: You need to read the voltage at the BATTERY at idle, 1500, and 2500 RPM to determine voltage regulator function. Better still would be a Volt Amp tester (VAT-40 Image below) to induce a correct AMP load to read actual AMP/Volt output from the alternator and battery, as that is the only true testing method. Having a DVM that has min/max capability will make your testing easy.
Step Three: Remove and clean each and every ground in the trunk, jump point, and at the frame rail for the block (bad grounds = lots of electrical issues). Clean the starter/alternator cable connection under the car, just under the dead pedal.
Step Four: Failure to get correct output on running test means DEAD alternator (volt regulator, brushes, windings, etc.) Remove and bench test the unit or drag it to your local auto parts store for a second opinion (which will be worth exactly what you pay for it....)

Base line numbers
Battery Voltage should be 12.6+V (Key off) See chart below.
Battery voltage should be 13.5v - 14.5v on running tests (note large fluctuations at running RPMs is a SURE sign that the Volt Regulator is not doing its job. Smack with rubber hammer and retest. Rebuilt units have large variance of quality control from good 85% of the time to approx 50/50%.

NOTE: The exact charging voltage will vary according to the battery's state of charge, the load on the vehicle's electrical system, and temperature. The lower the temperature the higher the charging voltage, and the higher the temperature the lower the charging voltage. The "normal" charging voltage on a typical application might be 13.8 to 14.3 volts at 77 degrees F. But at 20 degrees F. below zero, the charging voltage might be 14.9 to 15.3 volts. On a hot engine on a hot day, the normal charging voltage might drop to 13.5 to 14.3 volts.

Note 2: TIS specifies alternator voltage as 14.3 +/-0.1 V. But that is measured at the alternator output post. The values seen using the cluster will be 0.5 V or more below the alternator voltage output.

Batteries surface charge.

What the heck is a surface charge?
When testing wet cell auto batteries, some will show a 12.xx Volt result, but as soon as a 100-150 amp load is applied, they drop straight down to 9.8V or lower. Classic example of a collapsed cell wall (internal short). This is why too many DIY and techs get stumped when they pull out a meter and say "It shows 12.xxV so it must be good”. NOPE, batteries are tested for voltage holds and AMP draw capacity as well as the ability to recover and recharge over and over again. Batteries are nothing more than an energy storage device. Their usage back in the 1920's allowed for a "self-starter" option, now days we take it for granted. In the future we will use the engine ignition system to fire off a cyl while disabling all other cyls (opening the exhaust valves) allowing for a start that requires no electrical/mechanical starter. A topic for a SAE publication but an interesting future none the less. The challenge is for the average DIY to approx. the load test with KEY OFF.

Solution: Set a volt meter to DC volts 0-25 scale or auto ranging if so equipped. Read and record voltage
Turn on everything in the car for 15 seconds:
Headlamps to high beam
Heater blower motor to high w/ A/C on
Seat Heaters
Rear Defroster (and rear seat blower if so equipped)
Interior lights
Radio
Fog lamps
Cigar lighter
etc, etc, etc

Read voltage after testing. You should see a drop off of .5-1.5Volts during the test and a slow rise back to 12.5V+ on a completely healthy and fully charged battery in 30sec to 1 min.
A battery that is DEAD, will show 9.8V or less and never recover until charged.
Battery Registration: There is NO battery registration required for proper operations in a E39 or E53 application.

Alternator testing tips
To quote another poster...

How to load the alternator at engine idle for alternator output tests:

Note: Alternator output should be tested with the engine idling under the following four loads after at least 15 seconds of idling (for the alternator to ramp up):
Turn the high beams on
And, turn the rear defroster on
And, turn the fan on (full force, I guess)
And, turn the wipers on (to the regular setting, I guess)

These loads should be left on while the alternator output tests are being performed.

Once access to the alternator is gained (access for the I6 is vastly easier than the V8):

• Check the voltage from the alternator #30 post and ground
o It should be the same as the battery voltage
• Now disconnect the harness connector to the alternator:
• Check voltage from terminal 15 and ground (field voltage)
o It should be the same as the battery voltage

More info: Another way to check alternator output is with an oscilloscope. Observing the "ripple voltage" pattern will tell you at a glance whether or not all the alternator windings are functioning. A "good" pattern should look like the top of a picket fence. If any of the humps are missing, it means one or more of the windings is grounded or open, or there's a bad diode. Most battery/charging system testers also have a test function that can detect bad diodes.
Ripple testing with a DVM:

ANOTHER QUICK CHECK FOR BOSCH ALTERNATORS

One way to check the integrity of the alternator and diodes on Bosch alternators is to check the voltage readings at the D+ (blue wire) terminal and B+ terminal. The voltage reading should be the same at both terminals. A difference of more than one volt would indicate faulty diodes and the need to replace the alternator.
Tips link: https://www.diyauto.com/manufacturer...ion-by-bluebee

Volt Drop Testing (Image below) will show you issues with grounds and wiring problems. Read the text and test a few spots to determine if your car has clean connections.
https://www.engine-light-help.com/voltage-drop.html

Are you having other electrical issues? Alternative issues: Ignition Key switch failure, wiring junction box rusted (see water leaks under passenger seat (E39), Water standing in trunk under the battery (E53) and the normal wiring broken connectors, grounds), etc....

Tip Sites for more info:
https://www.aa1car.com/library/2002/cm10220.htm
https://www.bimmerfest.com/forums/sh...d.php?t=510579 (Everything you wanted to know about BMW starting and charging systems for DIY)
Need a Video? https://video.search.yahoo.com/searc...d&action=click

Helpful?

Thanks for the response, but I don't think that is the issue. I'm pretty certain I didn't leave the turn signal on when parking it. As for the F to C change, that happened while driving (when I adjusted the temp). I was possibly fussing with the temp buttons, but definitely not the odo. When I attempted to start the vehicle yesterday it had enough juice to turn on the electrical system and I did notice that the temp display had gone back to F. Maybe that was a completely unrelated issue, but I mentioned it bc it seemed awful coincidental.

BTW, I see you are from Racine...I grew up in Kenosha (now in Milwaukee).

Thanks for the tip. I will check on that. Alternator was just recently replaced (hopefully still under warranty), and battery is only 2.5 years old (its a 48 month).

Wow, thanks for the very in depth reply!!! I'm not sure how much of the above I will have the capacity to do myself, but will start looking into it and report back.

Sorry I forgot to include model/year...it is a 2006 X5 4.8is.

Previous electrical issues that were solved stemmed from a faulty ignition switch. Someone on the forum here pointed me in that direction, and I'm very thankful that they did bc my mechanic was about to tackle them all individually.

my x5 4.8is alt died with zero lights turning on nor the battery image display showing. Output was battery voltage (11.9V and falling)

Idk about E53, but in the E39 (5-series) forum, it was the defective Infineon chip inside the LCM. Info on bimmerfest (cost to fix was $5)...