Technical Tip

01-19-05TT Engine Crank, No Start or No -J623- ECM Communication with
DTC U0100 Stored in ECM Fault Memory

Transaction No:

2054867/4

Release date:

11/5/2021

Condition
ATTENTION:
THIS IS A TECH TIP, NOT A TECHNICAL BULLETIN.
TECH TIPS ARE NOT ASSOCIATED WITH WARRANTY CLAIMING.

Applicable Vehicles
Model(s)

Year

Eng. Code

Trans. Code

VIN Range From

VIN Range To

Arteon, Atlas,
Jetta,Golf, GTI,
Sportwagen,
Beetle, Beetle
Convertible,
Passat, Tiguan,
Tiguan LWB

2018-2019

All

All

All

All

Revision Table
Instance Number

Published Date

Version Number

Reason For Update

2054867/4

11/5/21

01-19-05TT

Include an additional step to
check fuse SB9 during the
procedure.

2054867/3

9/5/19

01-19-05TT

Update effected vehicles

2054867/2

4/29/19

01-19-05TT

Add figures 1 and 2.

2054867/1

4/26/19

01-19-05TT

Original publication.

Technical Background
DTC
U0100

Description
Lost Communication with ECM/PCM

When disconnecting the Battery during service, the -J623- (ECM) may become internally shorted as a result of the
Positive Battery Terminal grounding out on the ECM case. DTC U0100 may set, as well as an engine crank with no
start condition.

1

Technical Tip

01-19-05TT Engine Crank, No Start or No -J623- ECM Communication with
DTC U0100 Stored in ECM Fault Memory

Transaction No:

2054867/4

Release date:

11/5/2021

Service
When disconnecting or replacing a Battery, the Repair Manual procedure outlined in Elsa must be followed in its
entirety. See Repair Manual Group 27. The Battery Ground Cable must always be disconnected prior to the Battery
Positive Cable. Failure to do so may result in internal ECM damage.
Also check fuse SB9 for ignition coils to see if it is open. If the fuse is open it will need to be replaced.

Figure 1

Figure 2

.

Additional Information
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the latest information available at the time of printing and is subject to the copyright and other intellectual property
rights of Volkswagen Group of America, Inc., its affiliated companies and its licensors. All rights are reserved to make
changes at any time without notice. No part of this document may be reproduced, stored in a retrieval system, or
transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, nor may
these materials be modified or reposted to other sites, without the prior expressed written permission of the publisher.

2