4X4 Light On only - HELP!!!!
 

So recently my 4x4 light has come on. Just that light, not the ABS and brake lights. I've been searching the topic religiously the past couple weeks and noone really ever has a resolution. I have read a lot about the SAS but many say its very uncommon for that to be bad and it's usually something else.. I'm big into DIY and would to resolve this on my own without the stealership..

What I've done:
-Turn wheel lock-to-lock (about 50 times)
-Unhooked the battery for extended periods of time
-Went to Autozone, their reader says no codes.
-Used the OBC to check the voltage, it's 11.2V with engine off, and 12.8 when running. I've read it should be 12.25 minimum when not running.

I'm thinking it could be a bad battery..

My car is a 2004 X5 3.0i with 78k miles.

I've been in the E46 world for a long time and am new to the 5 series.

Any help or tips would be appreciated!!!

No codes at all? Do the cluster hack and see the voltage through it while driving:
BMW E38 Hidden OBC Functions

its not Alternator?....just turn off your car let it sit for like 3 mins...turn it on...and should go away....idk..mine does...but mine the voltage spikes....so my case was alternator.

FYI.. The Autozone reader can only check for "check engine" related codes.. Those codes are emissions control generic related codes... For anything else or BMW specific codes you need a different scanner than the $89 autozone scanner...

Yes I know this, I went there with high hopes. I'm certain it's sending a SAS fault code like everyone else with this problem. I don't have DIS so I can't see the codes..

What kind of spikes were you seeing? All through the cluster hack?

Do you think the voltage while driving will be much different them when just sitting at idle? What would I be looking for here?

With the info you posted about your battery's voltage...I'd focus right now on getting multiple readings from your battery at rest & engine not running (with no surface charge) and then while the engine is running and you're driving around.

Do you know if you are still using the original battery that came with the vehicle? If so, that may really point the finger at the battery being the culprit and it being on it's last dying legs. Even if the battery has been replaced...on average, it could be on it's 2nd battery...and at 9 years old...this wouldn't be out of line either since an automotive battery on general last from anywhere around 4 years to possibly 10 years depending on use & environment.

When you unlock your OBC...you should run TEST 9 before you start the engine or approx 2 hours after shutting down (this dissipates any surface charge)...then run TEST 9 while starting the engine and driving around. OBC TEST 9 shows you the battery's voltage (when engine is not running) and the alternator/charging system (when engine is running). This can give you an idea of where an electrical problem culprit may be.

The numbers you listed for engine not running & engine running are low. If the battery warning light hasn't illuminated (indicating an alternator/charging sytem problem)...then it could be a simple issue of your vehicle's battery giving you signs that it's about to fail.

A battery at 11.89 volts is at 0% state of charge and if still capable of starting the car...it's running on reserve capacity. You say that your battery was at 11.2 volts...and when voltage drops that low, odd electrical gremlins like warning lights illuminating but no symptoms can be found...are a common issue with many BMW models.

Again, unlock you OBC and do multiple TEST 9 samplings of the battery & alternator's voltage output (at rest & driving) and post back your findings. You should see some fluctuations at both rest & running...but for the most part, the battery should read above 12 volts...and the alternator should fluctuate between 12.5-13.8 volts consistently...depending on idle/load conditions.


Below is the procedure for unlocking the OBC (just like the link above) and there's also a brief description of the OBC TESTs. Disregard that it mentions "e38" in the heading...the "unlock" info applies to the e38/e39/e53 with the high instrument cluster...the low instrument cluster used in the e46 & e53 is similar except there's only 1 button on the cluster, so initiating the TESTs is slightly different as well as how they appear in the display since the low cluster doesn't have the larger 20-digit alpha/numeric display:

Qsilver7, thank you for the thorough follow-up! Appreciated
Last night after the car sat for about 4 hours is when I did the unlocked OBC Test 9 test, it was consistently 11.2 with engine not running and 12.8 max running. My E46 hovers between 13.8 and 14.2 all the time (Running or not).

I'm also fairly certain this is the original battery (Don't know for sure, but it really seems like it. I haven't looked for a date on it yet). I bought the car at 75k from someone that had it maintained it regularly at BMW. I can't find anywhere on the records of a new battery ever being installed.
Would it be worth hooking some jumper cables up for a little while to see if that alleviates my issues? Or should I just replace the battery straight away?

You can try charging the battery for a while to see if that changes anything (and get the 4x4 light to go off). But if it consistently reads around 11.2 volts and if it is the original battery...then you may find yourself stranded sometime in the near future if the battery dips so low that it can't start the vehicle (but may have enough juice to light the interior etc.)...or you may begin to see a few more odd electrical gremlins.

See if you can find a vendor that can load test the battery...which would give you another indication if its time to replace. If it needs to be replaced...you have the option of looking for 49/H8 or 95/H9 class size batteries. The prices can range from just around $100 to well up to $300. But again, the battery class size you're looking for is the 49/H8 and/or 95/H9...with the latter usually costing the most $$$. And don't forget to hook up any replacement battery to the VENT tube in the battery compartment since it's enclosed. ;)