Service Bulletin
October 25, 2019

19-097
Version 2

Service Manual Update: MOST Bus Network Failure Log
Supersedes 19-097, dated September 13, 2019, to revise the information highlighted in yellow.
AFFECTED VEHICLES
Year

Model

Trim

VIN Range

2018 - 20

Odyssey

ALL except LX

ALL

2019

Passport

ALL except Sport

ALL

2019 - 20

Pilot

ALL except LX

ALL

REVISION SUMMARY
Under DESCRIPTIONS, Troubleshooting Intermittent Network Failures, steps 1 and 2 were added.
BACKGROUND
Vehicles with system software version B.1.0.24 or higher now have the capability to log MOST bus network failures.

CUSTOMER INFORMATION:The information in this bulletin is intended for use only by skilled technicians who have the proper tools, equipment, and
training to correctly and safely maintain your vehicle. These procedures should not be attempted by “do-it-yourselfers,” and you should not assume
this bulletin applies to your vehicle, or that your vehicle has the condition described. To determine whether this information applies, contact an
authorized Honda automobile dealer.
©

2019 American Honda Motor Co., Inc. — All Rights Reserved

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DESCRIPTION
MOST Bus Network Failure Log
You will find the MOST Bus Network Failure Log under Dealer Diagnostics. Select DETAIL INFORMATION &
SETTING, then SHUTDOWN REASON.
The log includes the date, time and type of failure, making it easier to compare it to your customer's complaint. It can
hold up to 10,000 events.
To clear this log, you must select CLEAR from the screen. You cannot clear it using a factory data reset or battery cable
reset.

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Troubleshooting Intermittent Network Failures
NOTE
Before using this new feature, refer in the service information to the Audio and Visual System MOST Bus Diagnostics
Mode section as well as the Tech2Tech® video "Let's Talk MOST Bus Network and ECL Diagnostics" for basic
information on the MOST bus network operation.
The MOST Bus Network Failure Log lists the most recent event first, followed by the previous events in the order they
occurred. Each event is stamped and identified as one of these possible failures:
•

SUDDEN_SIGNAL_OFF: This failure is for a temporary complete loss of signal on the network.

•

CRITICAL_UNLOCK: This failure is for noise on the network.

This log can help confirm when your customer's complaint took place and what symptom occurred. These symptoms
may vary from a complete loss of signal and a blank screen, to an intermittent popping from the speakers. It also
identifies which control unit on the MOST bus network recorded the failure. The recording control unit tells you the
failure occurred between that control unit and the previous one on the network.
1. Turn the ignition to ON.
2. Press and hold the VOL/Power AUDIO knob, Day/Night icon, and HOME icon at the same time. Hold until you hear
a beep and the Dealer Diagnostics menu screen is displayed.
ODYSSEY

PASSPORT AND PILOT

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3. Select DETAIL INFORMATION & SETTING.

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4. Select SHUTDOWN REASON.

In this example, the cause of the failure can be identified as Meter:SUDDEN_SIGNAL_OFF.

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There was a complete loss of signal on the network between the meter (gauge control module) and the previous
transmitting unit on the network. In this example, the previous unit is the tuner or tuner-amplifier unit. Although the
specific cause is not identified, the failure was confirmed, and the components and connections that should be
inspected have been isolated.

Refer to the specific model and trim information in the Audio and Visual System MOST Bus Diagnostics Mode
section in order to determine each control unit's location on the network and identify where a failure potentially
occurred.
System Limitations
The MOST Bus Network Failure Log will not record during a permanent network failure and cannot be accessed during
that time. In the event of a current network failure, use the ECL test described under How to Check MOST Bus Network
Condition in the service information. During a current, complete network failure, ECL diagnosis is conducted by the
meter (gauge).
NOTE
The log is a recorded event - not a current failure. It can only be accessed when the MOST bus network and audio/
visual system are actually online.
Since the log can store up to 10,000 events, be sure to clear it when troubleshooting multiple control unit entries and
after any repairs have been made.
END

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