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Technical Service Bulletin
27 48V vehicle electrical system warning, DTC U046900 stored in the ECM
United States 444 Volkswagen of America, Inc. (6444)
[Status | Released for publishing
Release date Mar 4, 2025
Diagnostic trouble codes
. . . . Fault Storage
Diagnostic address Diagnostic trouble code
. « . |U046900: Invalid Data Received From Starter / .
0001 - Engine electronics Generator Control Module fo Intermittent
. « .« |U046900: Invalid Data Received From Starter / A
0001 - Engine electronics static
Generator Control Module
0019 - Data Bus OBD U046900: Invalid Data Received From Starter / .
Interface Generator Control Module Intermittent
0019 - Data Bus OBD U046900: Invalid Data Received From Starter / static
Interface Generator Control Module
New customer code
Object of complaint Complaint type [Position]
information, navigation, communication, entertainment -> malfunction functionality -> activates
display symbols -> vehicle electrical system malfunction indicator y
information, navigation, communication, entertainment -> malfunction functionality -> activates
display symbols -> vehicle electrical system malfunction indicator without cause
information, navigation, communication, entertainment -> malfunction functionality -> does not
display symbols -> vehicle electrical system malfunction indicator switch off/disconnect
New workshop code
Object of complaint Complaint type [Position]
power, vehicle electrical system, data transfer -> power supply -> generator | functionality -> misfire [|
Vehicle data
MLBevo with 48V MHEV
Sales types
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[_fzorsfa fees
[_fzorsfa tow
= powla [foc FO
pola [ioe
= feof fifo
= feoofa [dx SP Od
= feof [ides dP
= [eof [——idoces iF Od
= feoofa [ioe Od
= feof [omer Od
= feos [ioe POP
= poofa f —ioce PO
pola | dese
= pola for
= feozfa [fom FP
= leafed Od
= feozfa [ides Od
= [eozfa [ices
= feofa [ioe Od
= foasla [doce FO
= fowsfa f idee
= pola for
= feozsfa [fom FOP
= feof [ido Cd
PR numbers

Documents

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Technical Service Bulletin Transaction No.: 2058831/16
27 48V vehicle electrical system warning, DTC U046900 stored in the ECM Release date: Mar 4, 2025
Condition
REVISION HISTORY
[revision [pate [purpose
we Revised Additional information (Updated reference TSB)
15 11/20/2024 | Revised Warranty (Updated Claim Types, Labor Operations)
Revised Service (Added reference bulletin)
Revised Additional Information (Updated reference information)
14 04/26/2024 | Revised Service (Updated Requirements for Coverage)
Revised Warranty (Updated Labor Operations)
Customer states:
+ The message “Electrical system: malfunction! Please contact Service” is displayed on the instrument cluster
(Figure 1), in addition the battery symbol lights up in yellow or red.
+ Yellow warning lamp related to the electrical system shown in the instrument cluster during driving.
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Figure 1. Cluster Warning Message.
Workshop findings:
The following DTC is stored in the ECM, J623 (address word 0001):
+ DTC U046900: Invalid data received from starter/generator control module (symptom 36564).
Take note of the symptom 36564, if this is not present this TSB does not apply.
Technical Background

1. Hardware issue with belt-driven starter-alternator (diagnostic address 00CC).
2. Functional software issue with belt-driven starter-alternator (diagnostic address O0CC).
Production Solution
Not Applicable.
Service
If the complaint described above can be reproduced, then proceed as follows:
+ Check if ODIS S software is the latest version, update if necessary.
While diagnosing the 48V system ensure the 48V and 12V battery are charged properly prior to following
the procedure. Also, TSB 2067906: 27 48V Reference: Charging 48V Battery with 12V Charger DTC
P0A7D00 / POB2900 must be observed, otherwise a specific diagnosis is not possible.
In the diagnosis (not self-diagnosis), select the function test “C29 — read_delete and attach to test plan.
Note: Answer the question that appears in the test plan — “Are you running this program based on an
instruction in a TPI?” — with YES.
ODIS path for A4/A5/Q7:
+ Body
+ Electrical system
* 01 - On Board Diagnostic capable systems
+ CC - starter-alternator -C29
+ CC - Functions
+ 00CC — Check/erase event memory entry
ODIS path for A6G/A7/A8/Q8:
+ Diagnostic capable system
+ O0CC - starter alternator -C29
+ O0CC - Functions
+ 00CC — Check/erase event memory entry
If the following DTC is shown in ODIS, replace the starter-alternator according to ETKA and check whether the
complaint has been resolved:

+ B200096 — Faulty control module (active/static or passive/intermittent).

If the DTC is not stored in the test plan, then the generator is not faulty and replacing parts will not fix the
problem.

For invoicing under warranty, the above-mentioned DTC “B200096 - control unit defective” must be present
in the ODIS test plan “C29 — Read_Delete DTC” in the diagnostic log.
Important information on repair (replacement of belt-driven starter-alternator): risk of damage to radiator
outlet coolant temperature sender G83 or communication problems with new belt-driven starter-

alternator due to coolant entering the electrical connector.

Seal electrical connectors on coolant temperature sender, mating connector, signal connector to belt-driven
starter-alternator with leak-tight connector -T40348- or suitable workshop materials. Visually inspect
components for moisture before assembly and clean electrical contacts if necessary.

Note on working aid for required function checks for the event that the belt-driven starter-alternator needs
replacing:
The file “Working_aid_for necessary functional_tests” which is attached to this TSB contains the function
checks in ODIS which are required for this workshop visit.
Warranty

If Starter-alternator is not replaced:

Claim Type: + Ifthe vehicle is outside of any warranty, this Technical Service Bulletin is

informational only.
Damage Code: 0040
Labor Operations: GFF (only if starter-alternator is not replaced) 0150 0010 See SRT with
associated operations
GFF (only if starter-alternator is not replaced) 0150 0060 Time stated on the
diagnostic protocol

Claim Comment: As per TSB 2058831/16

OR

lf Starter-alternator is replaced:

Claim Type: + If the vehicle is outside of any warranty, this Technical Service Bulletin is

informational only.

Damage Code: 0040
Labor Operations: Replace starter-alternator (If required according |272619xx/ |See SRT with
to this TSB) 2726 55xx associated operations
12V battery Charge (if starter-alternator requires |2706 8950 See SRT with
replacement) associated operations
GFF (If starter-alternator requires replacement) |0150 0060 Time stated on the
diagnostic protocol
Claim Comment: As per TSB 2058831/16
All warranty claims submitted for payment must be in accordance with the Audi Warranty Policies and Procedures
Manual. Claims are subject to review or audit by Audi Warranty.
Required Parts and Tools
Exchange parts must be installed if available in the exchange program. If a new part is installed instead of an
exchange part in justified cases, the reason for this must be given in the comment field in SAGA/2.
Additional Information
The following Technical Service Bulletin will be necessary to complete this procedure:
+ TSB 2067906: 27 48V Reference: Charging 48V Battery with 12V Charger DTC POA7DO0 / POB2900.
All part and service references provided in this TSB (2058831) are subject to change and/or removal. Always check
with your Parts Department and/or ETKA for the latest information and parts bulletins. Please check the Repair
Manual for fasteners, bolts, nuts, and screws that require replacement during the repair.
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