2005 E330 CDI battery messages on instrument cluster - Page 2 - PeachParts Mercedes-Benz Forum

Dizzel · #16 03-23-2021, 11:53 AM

The comment about a deeper problem rings true.
Level II is when the voltage drops so low it is self preserving.
I had a situation where i measured the voltage at the battery during operation and it showed 14.3 volts so thought the alternator was fine. I just happened to be watching when the cooling fan came on and the voltage tanked.
Turned out to be a regulator. Alternator was fine, bearings good, sprag clutch on the pulley good and so on.
Replaced the regulator and all was good.
As noted by others here, you must get the correct Alt/regulator for the system to work.
Make sure the battery control module works also.

Bigdaddybenz · #17 03-25-2021, 08:29 AM

If the voltage regulator is defective then how is it that the battery is charging at over 14 vfc what appears as all of the time?.... Not 2nd guessing you but would like to understand!..

Also, what does it mean when you say the car will turn into a potato????

jay_bob · #18 03-26-2021, 12:16 PM

My answers below come from first and second person experience with a failure on our 2008 E320 Bluetec. The complete story at http://www.peachparts.com/shopforum/diesel-discussion/400578-w211-can-bus-problems.html. The problem ended up being water in the Central Gateway shorting out both CAN buses, but in the process of finding the problem I replaced the original alternator, twice.

Also in my real life I am an electrical engineer who works for a major electrical equipment manufacturer. I deal with multiple megawatt generators and UPSs in my daily mission to help keep the Internet running.

If the regulator straight up dies the output voltage on the alternator will vary with load and engine speed. In your original post you said the voltage was all over the place. This led me to recommend replacing the regulator, and to consider replacing the entire alternator due to age, since it is an essential component with a high probability of failure causing the vehicle to become inoperative at a very bad time.

The other failure mode is the LIN bus communication fails, but the regulator continues to regulate. In this case the voltage goes to 14.4 V +/- 0.2 V and holds there. I don’t think you have this problem. I think your regulator straight up died so it can’t communicate any more, based on your voltage observations and errors messages.

The correct operation of the regulator is that the output of the alternator is modulated, to suit not only the electrical system needs, but also to enhance engine performance and efficiency. The alternator is a load upon the engine, and there are certain times where it helps the engine performance to unload the alternator and rely briefly on the battery. This is further enhanced with the slip clutch. By telling the regulator to unload the alternator (by reducing the field excitation to zero) the freewheeling clutch reduces the mechanical load to near zero.

If the alternator cannot meet the electrical system needs there is enough intelligence to begin shedding non essential loads. This is the Convenience Functions Unavailable level 1 and 2. The loads are dumped in 2 stages, by de-energizing the circuits in the SAM modules via CAN bus messages, and corresponding messages posted on the console.

First things that are completely non essential are removed (lighter socket, seat heat, aux heater, rear defrost).

Level 2 it starts reducing climate fan speed, engine fan speed, the stereo, etc.

If you continue to decline the computers start shutting down. Climate control becomes non responsive. You lose your ABS/ESP, on the first generation 211, it’s worse, your SBS brakes go to failsafe. The transmission failsafes to second gear. Finally you lose enough power that the ECU can no longer calculate the fuel injection events, nor is there enough energy to fire the injectors, so the engine stalls. This is your potato mode.

Dizzel · #19 06-08-2021, 12:45 PM

Hey Bigdaddybenz

What was the outcome of you issue here?
Enquiring minds want to know.

Bigdaddybenz · #20 06-20-2021, 05:07 PM

quite honestly, I have yet to replace the alternator. It seems with the warmer weather I do not get the fault code as much, generally once when you first start the car. I do plan to change the alternator very soon. Every day I take a standing voltage reading before I start the car, lately it's been 11.8 volts, soon as it starts its resides at between 13.5 and 14.4 vdc.

I have opted to change the alternator as opposed to changing the regulator, I think that I can procure a decent alternator at my local Autozone.

Is Bosch the preferred alternator?

jay_bob · #21 06-20-2021, 09:37 PM

I highly recommend you stay away from parts store alternators. I got 2 lemons and had to end up going to the dealer. They will be refurbished, usually these come from south of the border, I had one that flat died after a month and the second one the LIN bus chip was dead so it would not communicate with the ECU. All this detailed out in my thread I linked previously.

This job is a pig on a 642, it may be easier on a 648 being an inline engine. Having to do it 2.5 hours from home in my son's rental house driveway (no garage) the second time was no picnic.

My suggestion pay the $450 and get it from the dealer and you won't have to worry. These are remanufactured from the Bosch or Valeo factories in Europe.

Your car will have been equipped from the factory with either a Bosch or a Valeo. They are not interchangeable, so you have to get the right one. This is another advantage to going with the dealer, they can look your VIN up in the EPC and it will tell the parts counter guy which one you need. As opposed to the computer in the parts store that gives you both options and you get a 50/50 guess, unless you get in there and physically look at the nameplate on your original one first.

Bigdaddybenz · #22 07-08-2021, 02:22 PM

Update... Well the alternator finally went. I attempted to purchase one from the dealership but they wanted a whopping $881.00 for the part and I refuse to pay that much. I took the bottom engine compartment covers off and it appears to be a Bosch 200 amp alternator. I found a match on Amazon and ordered that one for $221.00. As this is my first time changing an alternator on a W211 E320 cdi, the first thing I noticed was that this alternator, unlike ones that I changed on past Merecedes does not have through bolts but instead has 4 bolts coming through its side mounting in a different way. Looking under the vehicle, it appears that it cannot come out from the bottom but my perception is probably wrong as I have no clue how to take it out.

I started to take the center piece where the hood latch is located so that I may remove the fan shroud

If anyone has ever done this or has instructions on how to replace the alternator PLEASE be so kind as to share this information.

Luckily, the car did not turn into a potato, made it home, and still even starts. But the red battery warning stayed on for a long time so it is certain that I can not delay any further

Thank you all for your input and help@

Skid Row Joe · #23 07-09-2021, 12:33 AM

Did you ever install a new battery?

Bigdaddybenz · #24 07-09-2021, 07:14 AM

Yes. I Did!... The Auxiliary battery! Which actually still had good voltage!