4X4 Light On only - HELP!!!!

[Buguyed]

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!!!

[pezho405]

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

[Buguyed]

Originally Posted by pezho405

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

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

[Qsilver7]

Originally Posted by Buguyed

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:

[Buguyed]

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?

[Qsilver7]

Originally Posted by Qsilver7

...
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.

Your NEW battery is only at 11.7 volts? What's it's mfg date? Is it fresh or was it sitting on the shelf for a long time? Did the vendor charge the battery before installing it (especially if it has been sitting on the shelf for a while)?

What battery class size did you get? Is it a 49, H8, 95, or H9 class size (and hopefully it's vented)?

[Buguyed]

Your NEW battery is only at 11.7 volts? Yes
What's it's mfg date? Not sure i cant find that
Is it fresh or was it sitting on the shelf for a long time? It was on a shelf when I got it. Can't say for how long.
Did the vendor charge the battery before installing it (especially if it has been sitting on the shelf for a while)? No, I grabbed it and left.

What battery class size did you get? Is it a 49, H8, 95, or H9 class size (and hopefully it's vented)? H8 and yes it's vented.

[pezho405]

Originally Posted by Buguyed

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

On mine it was, i sometimes got spikes of 17 volts that put me in trans fail safe mode and other random electrical problems. Replaced the alternator and problems solved.

[Buguyed]

Originally Posted by pezho405

On mine it was, i sometimes got spikes of 17 volts that put me in trans fail safe mode and other random electrical problems. Replaced the alternator and problems solved.

Ok, i'll check that tonight as well. I haven't seen the trans fail safe mode yet.

The only other mystery problem happened yesterday.
We were leaving breakfast for mothers day. I walked to the car and hit unlock. The alarm started going off. I couldn't get it to stop, hitting all the buttons on the remote.
Finally, I got in the car and started it. Alarm still going off. Turned it off and got out, hit unlock again and it shut off. Embarrassing

Anyone think this could be related?

[Qsilver7]

Originally Posted by Buguyed

Ok, i'll check that tonight as well. I haven't seen the trans fail safe mode yet.

The only other mystery problem happened yesterday.
We were leaving breakfast for mothers day. I walked to the car and hit unlock. The alarm started going off. I couldn't get it to stop, hitting all the buttons on the remote.
Finally, I got in the car and started it. Alarm still going off. Turned it off and got out, hit unlock again and it shut off. Embarrassing

Anyone think this could be related?

This still sounds like a dying battery issue. When the voltage drops, again real weird electrical gremlins occur. Its like when a boxer gets hit with an uppercut and the electrical synapses in the brain don't connect...TKO...lights out...boxer sees stars, then head-dives into the canvas. When you're battery's voltage drops...similar things occur and it can't keep up with everything it's supposed to do....thus it starts and stops or basically goes into a type of rolling brown-out.

BTW, the alarm siren has it's own internal battery that is kept charge by the car's battery. If the vehicle's battery is low, then it can't keep the alarm siren's battery charged. The drop in current when the remote buttons are pressed in this condition...can be seen by the alarm siren as someone disconnecting power to the car and trying to steal it...so it sounds off.