Code 02254 & 003141

Phillip Diagnostician Anchorage, Alaska Posted   Latest   Edited   Bounty  
Bounty Ð3
Electrical
2007 Audi Q7 3.6L (BHK) 6-spd (0AT)
Intermittently Not Charging On Start Up. Code 02254-Interface To Generator

Okay vehicle came in originally for broken brake line, but notice that the battery was weak and that when the vehicle was first started cold sometimes vehicle would have no charging voltage. Warm vehicle seems to charge just fine. So all said and done customer had me look into it. Found 2 codes. 02254-Interface To Generator & 03041-Energy Management Active. The 03041 is just a battery saving feature from my understanding. So I found out that when that alternator would not charge on start up, if you snapped the throttle or raised the RPM's alternator would start charging. Also note that the battery was charged for half a day before I started diagnostics. In the battery regulation module pids, I found a pid for generator & generator interface. Generator interface pid reads not ok & gernerator pid reads ok. So I pulled the pico out and hooked up to the blue LIN-BUS wire. The blue LIN-BUS wire had around 500-600 mV with key on engine off. With key on engine running signal rose to charging system voltage and was a square wave. I unplugged the connector from the alternator and had the same square wave. From my understanding with key on I should have 12 volts on the LIN-BUS line and should be a pull down design. So I took a test light and jumped the LIN-BUS wire to 12 volts with the vehicle running and my generator interface pid then read ok. So I said to myself that alternator must be bad. I theorized that the alternator sends a 12 volt signal to the battery regulation module to let it know its okay. In turn the regulation module sends a pull down square wave signal back to control the alternator. Because the battery regulation module was not seeing the 12 volts from the alternator it was trying to wake it up with a 12 volt square wave signal. So a month later leading to today I get an alternator and install it. And find the same problem. Code came back after installing alternator and have a generator interface pid reading not okay. So now I am lost and do not know what to do now. I thought I understood how the system works from the reading and videos I watched but clearly I have zero clue.

… UPDATE: Was finally able to get back on this vehicle. I got access to the battery energy management module(BEM) Connectors look good at battery and BEM. NO voltage drop from battery to alternator. Have 12.19 volts at both input voltages to BEM. Both computer data lines are showing activity. I back probed the blue LIN-BUS from the BEM to the alternator and had 700 mV. Start the vehicle and voltage rises to charging voltage with a 12-0 volt square wave that stays pretty consistent. I noticed that if I unplug the BEM connector the LIN-BUS goes from 700 mV to battery voltage with vehicle KOEO. Also the part # for the BEM is 4L0 915 181. 

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Nuno Technician
Toronto, Ontario
Nuno
 

Was this alternator OEM or aftermarket. Reason I'm asking is because Audi uses different Lin numbers and frequencies when it comes to the voltage regulator.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

Directly from Audi. This was a customer supplied part but it was un opened in a Audi box. Numbers on the back of the alternator did match.

0 Ð3 Bounty Awarded
Pedro Owner/Technician
Cayey, Puerto Rico
Pedro
 

Try reset terminal 30 on the BEM(battery energy manager control module ) disrupt the power supply at terminal 30. If this does not resolve the complaint, you probably have a faulty BEM.

+1 Ð3 Bounty Awarded
Nuno Technician
Toronto, Ontario
Nuno
 

Did you check for possible voltage drop on the B+ terminal on the alternator. also make sure power and ground is good to the BEM

0 Ð3 Bounty Awarded
Christian Technical Support Specialist
Buxtehude, Germany
Christian
 

Please Check Part Number of BEM - 4L 910 181 = Most Bad , 4L0 910 181 A = Most Good, but had about 5 of these with that Code. I have Never had a Generator Fail without a Generator Pid = Fail, every (except one) Interface Gen. Failure was a bad BEM-Module. Only once had a bad Wire - After bad Front Crash repaired somewhere. Audi A6,A8 and Q7 all have this Problem regulary. Very Old Capture of…

+1 Ð3 Bounty Awarded
Steve Instructor
Irvine, California
Steve
   

If memory serve me me, the Gateway J533 and ECM controls the alternator. The BEM looks at the electrons moving in and out of the battery. Look at J519 for battery load determination. See if there are any output test from either J623 or J644 for the alternator.

0 Ð3 Bounty Awarded
Michael Mobile Technician
Clinton, Utah
Michael
 

Phillip, Have you reset the Battery Management System as if the battery were replaced? Many BMS systems have an algorithm that assumes degradation of the battery over time. If a battery is replaced and the system not reset, the system behaves abnormally. Ideally, the battery would need to be of the same type. (Flooded / AGM) The DIN / CCA needs to be the same as well. This model seems a little…

+1 Ð3 Bounty Awarded
Jonathan Technician
Digby, Nova Scotia
Jonathan
 

Will this vehicle charge when cold starting or is it random? I have seen alternators not charge when starting vehicle hot because there was no rpm flare like when the engine is cold.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

The problem only seems to happen cold. When the vehicle is warm I have yet to get to not charge. But it will only not charge if u don't raise the RPM's.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

… UPDATE: Was finally able to get back on this vehicle. I got access to the battery energy management module(BEM) Connectors look good at battery and BEM. NO voltage drop from battery to alternator. Have 12.19 volts at both input voltages to BEM. Both computer data lines are showing activity. I back probed the blue LIN-BUS from the BEM to the alternator and had 700 mV. Start the vehicle…

0 Ð3 Bounty Awarded
Chris Diagnostician
Commack, New York
Chris
 

Can you post shots of the pattern? Also did you register your battery. The energy management code worries me.

+1 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

I'm out sick today. But a battery was never installed since I started working on it. This vehicle does has an interstate battery that I do not know when was installed. As soon as I am back at work I will do a a scope capture.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
   

I posted some pico files here. Let me know if you need any clarification on what is what.

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Caleb Technician
Mishawaka, Indiana
Caleb
 

Although Chris is much more qualified than me to help you with this one. I would be very concerned about battery registration or lack of ecspecially with the Interstate battery.

0 Ð3 Bounty Awarded
Bryan Owner/Technician
Logan, Utah
Bryan
 

I had a similar issue. There is a a ground in the harness passenger side lower engine compartment that was pulled from the connector. The ground was pulled loose from adventurous driving, was the issue present before the broken brake line? I have not had any issues with interstate so long as they are the correct battery and registered correctly.

0 Ð3 Bounty Awarded
Nuno Technician
Toronto, Ontario
Nuno
 

Could it possibly be that the BEM needs a software update.

0 Ð3 Bounty Awarded
Nuno Technician
Toronto, Ontario
Nuno
 

Reading more on this vehicle. If alternator was replaced there's a possibility that the Bem isn't recognizing the regulator on the alternator. alternator might have an updated regulator so BEM might need to have the software updated also. Hope this helps.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

Sorry for the long delay i had strep so today is the real first day I been back. Here are some screen shot from scan tool . and some pico files.

0 Ð3 Bounty Awarded
Chris Diagnostician
Commack, New York
Chris
 

Here is what I see: The alternator is not LIN bus controlled. Rather, it is duty cycle controlled. What we need to know is if the alternator is charging the vehicle here also, we need to know if the alternator is charging the vehicle here If the alternator is not charging at either one of those instances, You need to START with an alternator. Let's not mess around, get an OEM one from the…

+1 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

no in both situations the alternator was not charging. I also compared duty cycle voltage to battery voltage and they would match. Also to make note and make sure you have all the information is if I snap the throttle the alternator will start charging in both those situations. And this vehicle does have a new OEM alternator installed by me. I will attempt the battery registration in a bit. I am…

0 Ð3 Bounty Awarded
Chris Diagnostician
Commack, New York
Chris
 

You can register an aftermarket battery to this vehicle. Just make sure it is the correct size. When it comes time to put in a serial number, just make it "…" What is the demand for the alternator? look for it in the ecm (01) or j519 (09)

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

I couldn't find anything in the 01 or 09 modules. I did find this in the energy management 61 . What I'll do is tomorrow record data with vehicle not charging and with vehicle charging and send those to you. Unfortunately I can't do it today due to parenting responsibilities and the vehicle has to sit a while before not charging situation will happen again.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

I could not get vehicle to not charge today. Also I found out that the battery for the vehicle is not correct. Here is some screen shots from when the vehicle was charging. I also have the file for the saved launch data pids if you like them.

0 Ð3 Bounty Awarded
Chris Diagnostician
Commack, New York
Chris
 

just so we are 100% clear, this is a 100% new OEM alternator FROM AUDI, in an Audi box? Frankly for you to have command, and no charging, is pretty clear cut. Did you check the voltage at the back of the alternator and the battery?

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

I just got off the phone with Audi and the alternator is a re-manufacturer alternator from them. (the parts guy know the customer vehicle and was the one that sold it) Voltage was checked at back of the alternator, the engine bay stud & at battery. I would think it be clear cut too, but because I had no info on the codes and no code setting description is was thinking I had misdiagnosed the…

0 Ð3 Bounty Awarded
Chris Diagnostician
Commack, New York
Chris
 

I don't think you did. You have control to the back of the alternator and no charging response, also the alternator comes back to life when you goose the throttle. Charge and register that battery before going any further. If you do not want to register that one, I won't fault you for putting the correct one in there

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

should I but … for the VAG # as well as the serial number for the battery registration right?

0 Ð3 Bounty Awarded
Chris Diagnostician
Commack, New York
Chris
 

if it is an OEM battery, put the part number of that battery. If it is aftermarket, look up the corresponding OEM number on Worldpac or something similar. The serial number will be …

0 Ð3 Bounty Awarded
Nuno Technician
Toronto, Ontario
Nuno
 

Would you be able to provide me with the numbers on the alternator.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

The old alternator and the new one have the exact part numbers excluding the production date.

0 Ð3 Bounty Awarded
Nuno Technician
Toronto, Ontario
Nuno
 

Could you please provide the Vin# i have a buddy at Audi. He's asking g for the vin#

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

WA1BY74L57D072856

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Nuno Technician
Toronto, Ontario
Nuno
 

Does the alternator have a good ground.

0 Ð3 Bounty Awarded
Phillip Diagnostician
Anchorage, Alaska
Phillip
 

I normally check the alternator output by connecting to the alternator case and to the back of the alternator B+terminal I also will measure amperage coming from alternator also.

0 Ð3 Bounty Awarded
Nuno Technician
Toronto, Ontario
Nuno
 

That was going to be my next suggestion. My buddy at Audi also said that they have had issues with the Audi remanufactured units. Another suggestion would be to send the unit out to a local rebuilder and have them test it out for the specific vehicle. They have a com box they use to communicate with the alternator.

0 Ð3 Bounty Awarded