SAE J1939 Data Link - Cannot Transmit Page 1 of 6
FAULT CODE 426
SAE J1939 Data Link - Cannot Transmit
Overview
CODE REASON EFFECT
Fault Code: 426 SAE J1939 data link - cannot transmit. None on performance.
PID: S231 Communication between the ECM and J1939 devices possibly
SPN: 639 another device on the SAE J1939 data link do not operate.
FMI: 2 has been lost.
LAMP: None
SRT:
SAE J1939 Data Link Circuit
Circuit Description
Devices such as automatic braking system controllers, autoshift transmissions, vehicle
electronic control module (ECM), automatic slip reduction systems, electronic displays,
electronic information systems, electronic service tools, and vehicle electronic control unit
(s) can communicate with the ECM over the J1939 data link. Messages sent from the
devices are received by the ECM and used for controlling the engine. The ECM also
transmits information to these devices over the J1939 data link.
Component Location
The ECM is located on the intake side of the engine, near the front. The J1939 data link
wiring and the SAE J1939 devices vary by OEM options.
Shop Talk
This fault occurs whenever the ECM starts communicating with any other device using the
SAE J1939 data link and then can no longer transmit on the data link. Possible causes
could be the following: Unplugging an electronic service tool before keying off the ECM, the
SAE J1939 data link having an intermittent electrical problem, and the ECM (or another
SAE J1939 device) tying up communications because of an electrical problem or by
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sending too many messages without stopping.
Cautions and Warnings
CAUTION
To reduce the possibility of pin and harness damage, use the following
service tools when taking a measurement:
Part Number 3163151 - ECM Bench Top Calibration Harness
Part Number 3164185 - ECM Bench Calibration Adapter Cable.
Troubleshooting Steps
STEPS SPECIFICATIONS
STEP 1. Check the SAE J1939
communication.
STEP 1A. Check for ECM Does INSITE™ electronic service tool
communication with INSITE™ communicate with the ECM?
electronic service tool.
STEP 1B. Inspect the OEM Dirty or damaged pins?
harness and ECM connector pins.
STEP 1C. Check ECM Does INSITE™ electronic service tool
communication with the ECM communicate with the ECM?
bench calibration harness.
STEP 2. Clear the fault codes.
STEP 2A. Disable the fault code. Fault Code 426 inactive?
STEP 2B. Clear the inactive fault All fault codes cleared?
codes.
Guided Step 1 - Check the SAE J1939 communication.
Guided Step 1A - Check for ECM communication with INSITE™ electronic
service tool.
Conditions
z Connect the INLINE™ II data link
adapter to the vehicle SAE J1939
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data link diagnostic connector.
z Connect the INSITE™ electronic
service tool.
z Turn keyswitch ON.
Action
Attempt to communicate with the ECM
use INSITE™ electronic service tool.
z Start INSITE™ electronic service
tool and connect to the ECM use
an INLINE™ II (J1939) ECM
connection.
Does INSITE™ electronic service tool Does INSITE™ electronic service tool
communicate with the ECM? communicate with the ECM?
YES NO
The ECM SAE J1939 data link circuit is No Repair
functioning properly.
Refer to the OEM troubleshooting and
repair manual for information on
troubleshooting the vehicle SAE J1939
network.
Refer to the OEM troubleshooting and
repair manual for information on
Go to 1B
troubleshooting and vehicle SAE J1939
network
Guided Step 1B - Inspect the OEM harness and ECM connector pins.
Conditions
z Turn keyswitch OFF.
z Disconnect the OEM harness from
the ECM.
Action
Inspect the OEM harness and ECM
connectors for the following:
z Corroded pins
z Bent or broken pins
z Pushed back or expanded pins
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z Moisture in or on the connector
z Missing or damaged connector
seals
z Dirt or debris in or on the
connector pins.
For general inspection techniques, refer
to Component Connector and Pin
Inspection, Procedure 019-361.
Dirty or damaged pins? Dirty or damaged pins?
YES NO
Clean the connectors and pins. No Repair
Repair the damaged harness, connectors,
or pins if possible.
Refer to the Resistance Measurements
Using a Multimeter and Wiring Diagram,
Procedure 019-360.
Go to 2A Go to 1C
Guided Step 1C - Check ECM communication with the ECM bench
calibration harness.
Conditions
z Turn keyswitch OFF.
z Disconnect the OEM harness from
the ECM.
z Connect the ECM bench
calibration harness to the ECM.
z Connect the INLINE™ II data link
adapter.
z Turn keyswitch ON.
z Connect INSITE™ electronic
service tool.
Action
Attempt to communicate with the ECM
using INSITE™ electronic service tool.
z Start INSITE™ electronic service
tool and connect to the ECM with
an INLINE™ II (J1939) ECM
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SAE J1939 Data Link - Cannot Transmit Page 5 of 6
connection.
Does INSITE™ electronic service tool Does INSITE™ electronic service tool
communicate with the ECM? communicate with the ECM?
YES NO
INSITE™ electronic service tool is able to No Repair
communicate with the ECM. This indicates
that the ECM data link circuit is functioning
properly.
Refer to the OEM troubleshooting and
repair manual for information on
troubleshooting the vehicle SAE J1939
network.
Refer to the Communication Error -
Refer to the OEM troubleshooting and
Electronic Service Tool or Control
repair manual
Device troubleshooting symptom tree
Guided Step 2 - Clear the fault codes.
Guided Step 2A - Disable the fault code.
Conditions
z Connect all components.
z Turn keyswitch ON.
Action
Disable the fault code.
z Start the engine and let it idle for
one minute.
z Verify that Fault Code 426 is
inactive.
Fault Code 426 inactive? Fault Code 426 inactive?
YES NO
No Repair No Repair
Go to 2B Go to 1A
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Guided Step 2B - Clear the inactive fault codes.
Conditions
z Connect all components.
z Turn keyswitch ON.
Action
Clear the inactive fault codes.
z Use INSITE™ electronic service
tool, erase the inactive fault
codes .
All fault codes cleared? All fault codes cleared?
YES NO
No Repair No Repair
Repair complete Appropriate troubleshooting steps
Last Modified: 21-Mar-2005
Copyright© 2005
Cummins, Inc.
All rights reserved
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