Intermittent Battery and 4x4 inop lights

I have been experiencing intermittent red battery light and yellow 4x4 inop light. Shutting engine down and restarting resets the lights and all is normal. Last week I needed to change the battery since it failed. My indy tested the alternator and it tested just fine - even showed me a hard copy of the test result. Today I got a red battery light for about 5 minutes then it went out on its own. After a few minutes the 4x4 inop light came on and stayed on until the engine was shut down. All lights were cleared after the engine was restarted. Anyone have any ideas what is going on here?

Something in your car's charging system isn't right. The light comes on when the battery is the VICTIM of not being charged (as stated in the owners manual). That could be from the alternator at some point not charging correctly (an intermittent regulator issue?)...or it could be a slipping belt, or bad pulley/tensioner.

What ever it is...it is going to eventually kill your new battery if not taken care of. Have you UNLOCKED your OBC? If you have, you can run TEST 9 while the engine is running (and you're driving around) and keep an eye on how your alternator/charging system is performing. If it is dipping/dropping consistently below 12 volts ...that would be the reason the red warning light is coming on. When the ignition is in position 1 or 2 (engine NOT running)...it will show the battery's voltage (which you can also check to see if it is being damaged by inconsistent recharging from the car's charging system. When the engine is RUNNING then the alternator/charging system's voltage is being displayed in TEST 9.

It is best to check the battery on a cold engine or a few hours after shut down so that there's no "surface charge" giving you an inaccurate condition of the battery. See the info below on how to remove surface charge...and an idea of battery voltage readings. The battery gives up its resources to start the engine...once started, the alternator/charging system replenishes the battery's reserves. If the alternator/charging system is failing to recharge the battery...then the battery warning light illuminates to alert you of this condition. If the battery never gets replenished...then it will eventually become deeply discharged or die.

Again, this warning illuminates when the battery is the VICTIM...not the CULPRIT

If the term UNLOCKED OBC is foreign to you...go to this link to learn how to UNLOCK your OBC and for information about what the 21 TESTs are that you can access once UNLOCKED:

http://www.cardomain.com/ride/313409...series/page-6/

example: this is the 1st page which shows how to UNLOCK the OBC (works on all BMW high clusters incl the e53)

Here's a video of an e53 owner chasing a battery warning light issue...seems like his situation was caused by water intrusion which shorted the voltage regulator. That's not to say this is your issue...more trouble shooting would be required to determine if your situation is similar:

Thanks QSilver7 - this is helpful. I could not read how to unlock the OBC as the print is too small and the pages do not open up when clicked. Also, how does the yellow 4x4 triangle in a circle symbol relate to this battery fault?

[QUOTE=QSilver7;7284540]Here's a video of an e53 owner chasing a battery warning light issue...seems like his situation was caused by water intrusion which shorted the voltage regulator. That's not to say this is your issue...more trouble shooting would be required to determine if your situation is similar:

[/QUOTE

I successfully unlocked the OBC through another website and set the system to test #9. With ignition on, engine off, I am reading 11.9 to 12.2 volts with a new battery. With engine on at idle I read 13.9 to 14 volts. I will monitor this for few days and see if it stays consistent. Also checked my current and pending fault codes and they are clear. So I am not sure what is going on as this all appears normal. My belts are tight and not slipping that I can see. The red battery symbol light essentially functions as an alternator light and it only comes on when the alternator is not charging the battery. So why it is coming on every so often and going out after a few minutes? Could it be a faulty (intermittent)voltage regulator? And how would this issue relate to the yellow 4x4 triangle in a circle (DSC) symbol illuminating?

I checked the battery voltage througth the OBC after the X-5 was sitting overnight for 14 hours. Battery voltage read 11.7 volts with an outside air temp of 30 degrees. Started the engine and did not see the voltage increase but rather started to decrease a little to 11.6, then 11.5. Pulled the X-5 out of the garage and headed to work. For the next 1/4 mile the voltage remained at 11.5 and clearly not charging. While stopped at a traffic light I felt the engine surge a little bit then watched the voltage rise to 13.9 volts. The alternator just kicked in. I pulled the X-5 over and checked the fault codes with my Creader VI scanner and all was clear. No current or pending faults. I should have done that before the alternator came on line but did have presence of mind to do so at that time. Anyway. the battery light never came on because I believe the voltage didn't drop below the voltage threshold that triggers the light. Driving on the interstate to work the charging voltage read 13.9 to 14.1 volts. When I arrived at work I checked the battery voltage after shutdown and it read 12.2 volts. So I do have a intermittent problem but still uncertain what it is. Could this be pointing to the voltage regulator?

Alternator...it should NEVER drop below 12 volts while the engine is running. The alternator shouldn't "kick-in" 1/4 mile down the road...it should be working as soon as the engine is running and the belts & pulleys are turning.

Originally Posted by QSilver7

Alternator...it should NEVER drop below 12 volts while the engine is running. The alternator shouldn't "kick-in" 1/4 mile down the road...it should be working as soon as the engine is running and the belts & pulleys are turning.

Other than the short episode yesterday (3 minutes) the alternator continued to charge uninterrupted normally at 14 volts during my commute to and from work - about a 2 hour round trip. I will check the belt and pulley again today to be certain but I guess the alternator is showing early signs of failure....even though it is not throwing fault codes.

I always thought that when an alternator fails, it fails totally. You have it or you don't; not in an intermittent fashion as I am experiencing. This points to a slipping belt. As for the voltage regulator, I am not seeing any other indications like fluctuation in dimming lights. I assume if it where the regulator, it cannot be replaced on the alternator without removing the alternator and if so I may as well replace the entire assembly. So short of a slipping belt I need to start shopping for a new alternator. Make sense????

Originally Posted by QSilver7

Alternator...it should NEVER drop below 12 volts while the engine is running. The alternator shouldn't "kick-in" 1/4 mile down the road...it should be working as soon as the engine is running and the belts & pulleys are turning.

I checked the alternator belt and it appears tight - have about 3/4"-1" play when pressing the belt in the middle and it appears the spring loaded tensioner is working but I cannot rule out belt slippage. Had the same alternator problem this morning. Outside temp 30 degrees - had 11.7 volts on the battery prior to start up. Started engine and voltages declined to 11.6, then 11.5 which triggered the red battery light to come on. I rev'd the engine and voltage did not increase. No strange noises coming from the engine compartment. I plugged in my Creader scanner and there were no current or pending faults. All green lights. After the engine was on for 3-4 minutes I once again heard the engine labor down a bit when the alternator kicked in on-line and started charging at 14 volts. I commuted to work and it stayed at 13.9 to 14 volts the whole one hour trip - all normal.

I am seeing a common denominator with this problem. Each time the battery light has come on in the past 3 weeks it has been soon after the first engine start of the day when the engine was cold and the outside temperature around 30 degrees. I observed on a couple of occasions, through voltage test 9 that when the engine started, the alternator did not charge and when the voltage drops to 11.5 the red battery light comes on. This explains why, before I started monitoring the test 9 voltage output, everything looks good initially and when the voltage drops after a few minutes, I get the battery light. Then after 5- 15 minutes the alternator starts charging on its own and the light goes out. Once warmed up after a few minutes the system charges at 14V normally all day long. This is just a problem in the mornings for a few minutes. So I am experiencing delayed charging in cold weather. I am trying to zero in specifically on what needs to be fixed, if anything at this point, before I arbitrarily replace the alternator.

The alternator is original equipment and has 78k miles on it. I am thinking cold weather belt slippage or a faulty voltage regulator. I can see where a cold belt could slip but grip better once things heat up. Same for the spring loaded tensioner. That could explain the few minutes delay kicking in after warm up. Regarding the voltage regulator - Does it have contacts or is there a relay in the circuit somewhere which may be affected by cold weather? Any thoughts?