Primary Data Link (J1939 A) (TRTS0950) (2024)

Table of Contents
Fault Code 115: Primary Data Link (J1939 A) J1939: SA 3 SPN 639 FMI 2, 8, 9, 14, 19, 31 Overview Detection Conditions to Set Fault Code Active Fallback Conditions to Set Fault Code Inactive Possible Causes Additional Tools Component Identification Fault Code 115 Troubleshooting References

Fault Code 115: Primary Data Link (J1939 A)

J1939: SA 3 SPN 639 FMI 2, 8, 9, 14, 19, 31

Overview

The Transmission Control Module (TCM) communicates with other vehicle Electronic Control Units (ECUs) over the vehicle J1939 data link. The TCM uses two vehicle J1939 data links to send and receive messages called the Primary Data Link and Secondary Data Link. The Primary Data Link is used by the TCM to communicate with the Engine, ABS, Body, and other vehicle ECUs during normal operation. The Secondary Data Link is used as a backup in the event that the Primary Data Link is inoperative. The Primary Data Link is connected to the TCM at the 20-Way TCM Vehicle Harness Connector.

Detection

The TCM monitors messages broadcast over the vehicle Primary Data Link (J1939 A). If vehicle or engine messages are not received or in error, the fault is set active.

Conditions to Set Fault Code Active

FMI 2 – Data Erratic: Vehicle Primary Data Link (J1939 A) messages not received for 1 second (Service).

FMI 8 – Abnormal Frequency: Engine Primary Data Link (J1939 A) messages not received for 1 second while the TCM is receiving messages from other vehicle ECUs (Service).

FMI 9 – Abnormal Update Rate: Vehicle Primary Data Link (J1939 A) messages not received for 5 seconds.

FMI 14 – Special Instructions: Engine Primary Data Link (J1939 A) messages not received for 5 seconds while the TCM is receiving messages from other vehicle ECUs.

FMI 19 – Received Network Data In Error: Vehicle Primary Data Link (J1939 A) messages received but in error.

FMI 31 – Condition Exists: Vehicle Primary Data Link (J1939 A) receiving a “Stop Start Broadcast” message.

Fallback

FMI 2, 8, 19:

  • Amber warning lamp on
  • No degraded modes

FMI 9, 14:

  • Amber warning lamp on
  • If vehicle is configured for J1939 Start Enable feature, engine may not crank
  • Lowest available start gear only
  • Urge to Move and Creep prohibited
  • Launch quality may degrade
  • Upshifts prohibited
  • PTO mode prohibited
  • If vehicle is moving and transmission is in a gear higher than the lowest available start gear and Secondary Data Link is not available:
    • Red stop lamp on
    • Clutch engagement prohibited, vehicle may coast to stop
    • Transmission downshifts to lowest available start gear

FMI 31:

  • Amber warning lamp on
  • If vehicle is configured for J1939 Start Enable feature, engine may not crank
  • Lowest available start gear only
  • Urge to Move and Creep prohibited
  • Launch quality may degrade
  • Upshifts prohibited
  • PTO mode prohibited
  • Non-Neutral modes prohibited

Conditions to Set Fault Code Inactive

FMI 2: Valid vehicle Primary Data Link (J1939 A) messages received for 20 seconds.

FMI 8: Valid engine Primary Data Link (J1939 A) messages received for 20 seconds.

FMI 9: Valid vehicle Primary Data Link (J1939 A) messages received for 10 seconds.

FMI 14: Valid engine Primary Data Link (J1939 A) messages received for 10 seconds.

FMI 19: Key cycle and condition no longer exists.

FMI 31: Condition no longer exists.

Possible Causes

FMI 2, 9:

  • Vehicle Primary Data Link (J1939 A)
    • Wiring shorted to ground, shorted to power or open
    • Bent, spread, or loose terminals
    • Excessive electrical noise
    • Missing or additional terminating resistors
  • Other Vehicle ECU(s)
    • Internal failure

FMI 8, 14:

  • Vehicle Primary Data Link (J1939 A) – Between Engine ECU and TCM
    • Wiring shorted to ground, shorted to power or open
    • Bent, spread, or loose terminals
    • Excessive electrical noise
    • Missing or additional terminating resistors
  • Engine ECU
    • Not powering up
    • Internal failure

FMI 19:

  • Other Vehicle ECU(s)
    • Internal failure

FMI 31:

  • Other Vehicle ECU(s)
    • Informational only, indicates a Vehicle ECU experienced a programming event.

Additional Tools

  • Endurant HD Service Manual TRSM0950
  • Digital Volt Ohm Meter (DVOM)

Component Identification

Primary Data Link (J1939 A) (TRTS0950) (1)

1. 20-Way TCM Vehicle Harness Connector

2. 20-Way TCM Body Harness Connector

3. Transmission Control Module (TCM)

4. 9-Way Type 2 Diagnostic Connector (In Cab)

Primary Data Link (J1939 A) (TRTS0950) (2)

1. Transmission Control Module (TCM)

2. 20-Way TCM Vehicle Harness Connector

3. 20-Way TCM Body Harness Connector

4A. 9-Way Type 2 Diagnostic Connector (OEM-Specific Primary Data Link FG)

4B. 9-Way Type 2 Diagnostic Connector (OEM-Specific Primary Data Link CD)

Primary Data Link (J1939 A) (TRTS0950) (3)

Fault Code 115 Troubleshooting

A

Purpose:Check for active or inactive fault codes.

  1. Set vehicle parking brake and chock wheels.

  2. Record the transmission fault codes, FMIs, occurrences, and timestamps from the Service Activity report created during the Diagnostic Procedure.

  • If Fault Code 115 FMI 2, 9 is Active, Go to Step C

  • If Fault Code 115 FMI 2, 9 is Inactive, Go to Step B

    Note: If ServiceRanger connects to the TCM, the vehicle data link is currently functional between the 9-Way Diagnostic Connector and TCM. Refer to OEM guidelines for vehicle data link diagnostic instructions.

  • If Fault Code 115 FMI 14 is Active, Go to Step O

    Note: If ServiceRanger connects to the TCM, the vehicle data link is currently functional between the 9-Way Diagnostic Connector and TCM. Refer to OEM guidelines for Engine ECU and vehicle data link diagnostic instructions.

  • If Fault Code 115 FMI 14 is Inactive, an intermittent condition may exist on the Primary Data Link with the following:

    • Power up issue with the Engine ECU
    • Vehicle Primary Data Link to the Engine ECU
    • Fault(s) reported from the Engine ECU
    • Refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939A) or Engine ECU. Go to Step V

  • If Fault Code 115 FMI 19 is Active, a condition may exist on the Primary Data Link with the Engine ECU or other Vehicle ECU(s) reporting an issue. Refer to OEM for further diagnostic instructions. Go to Step V

  • If Fault Code 115 FMI 19 is Inactive, an intermittent condition may exist on the Primary Data Link with the Engine ECU or other Vehicle ECU(s) reporting an issue. Contact OEM for further diagnostic instructions. Go to Step V

  • If Fault Code 115 FMI 31 is Inactive or Active, informational only, indicates a vehicle ECU experienced a programming event. Test complete.

B

Purpose:Use Product Diagnostic (PD) Test to locate intermittent failures.

  1. Key on with engine off.

  2. Connect ServiceRanger.

  3. Go To “Service Routines”

  4. Start Product Diagnostic Test and follow on-screen prompts.

    Note: Solid “PD” may appear in display when PD Test is active.

    Note: TCM will not enter PD Test mode when there are Active fault code.

    Primary Data Link (J1939 A) (TRTS0950) (4)

  5. Wiggle the vehicle harness and connections between the charging/battery system and 20-Way TCM Vehicle Harness Connector. Look for signs of rubbing or chafing on the wires. Refer to OEM wiring diagrams.

    See Also
    What Is Fault Code SPN 639 FMI 9? (Cummins, Freightliner)Volvo's SPN FMI Code List: The Ultimate Reference for TroubleshootingInternational Trucks Diagnostics Trouble Codes (DTCs) | Truckmanualshub.comWhat are SA SPN FMI - Beginners guide to fault codes

  6. To end the test, press the stop button.

  • If fault codes set Active while wiggling the vehicle harness, refer to OEM guidelines for repair or replacement of the vehicle harness and/or the 20-Way TCM Vehicle Harness Connector. Go to Step V

  • If no fault codes become Active, Go to Step D

C

Purpose:Verify fault status with 20-Way TCM Body Harness Connector disconnected.

  1. Key off.

  2. Disconnect 20-Way TCM Body Harness Connector.

  3. Key on with engine off.

  4. Connect ServiceRanger.

  5. Retrieve and record the transmission fault codes, FMIs, occurrences, and timestamps.

  • If Fault Code 115 is now Inactive, a wiring issue exists with the Secondary Data Link (J1939 B) within the 20-Way TCM Body Harness Connector or harness. Refer to OEM guidelines for repair or replacement. Go to Step V

  • If Fault Code 115 was Inactive or remains Active, key off and reconnect 20-Way TCM Body Harness Connector. Go to Step D

D

Purpose:Identify TCM location on Vehicle Primary Data Link (J1939 A).

  1. Key off.

  2. Refer to the OEM and identify the TCM location on the Vehicle Primary Data Link (J1939A) at the 9-Way Diagnostic Connector.

  • If the TCM is on 9-Way Diagnostic Connector Pin C and Pin D, Go to Step J

  • If the TCM is on 9-Way Diagnostic Connector Pin F and Pin G, Go to Step E

E

Purpose:Verify Vehicle Primary Data Link (J1939 A) signal voltage.

  1. Key on with engine off.

  2. Measure voltage between 9-Way Diagnostic Connector Pin F and Pin A. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (5)

  3. Measure voltage between 9-Way Diagnostic Connector Pin G and Pin A. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (6)

  4. Record the total voltage by adding together the voltage readings.

  5. Compare reading(s) in table.

  • If readings are in range, Go to Step F

  • If readings are out of range, refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939 A). Go to Step V

PinsRangeReading(s)
F to AN/A
G to AN/A+
Total Voltage4.5–5.5 V=

F

Purpose:Verify resistance of Vehicle Primary Data Link (J1939 A).

  1. Key off.

  2. Measure resistance between 9-Way Diagnostic Connector Pin F and Pin G. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (7)

  3. Compare reading(s) in table.

  • If readings are out of range, refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939 A). Go to Step V

  • If readings are in range, Go to Step G

PinsRangeReading(s)
F to G50–70 Ohms

G

Purpose:Verify 20-Way TCM Vehicle Harness Connector condition.

  1. Key off.

  2. Disconnect the 20-way TCM Vehicle Harness Connector.

  3. Inspect the 20-Way TCM Vehicle Harness Connector, verify the connector is free from contamination and corrosion; the terminals are not bent, spread or loose; and there is no damage to the connector body.

  4. Inspect the TCM side of the 20-Way TCM Vehicle Harness Connector, verify the connector is free from contamination and corrosion; the terminals are not bent, spread or loose; and there is no damage to the connector body.

  • If contamination or damage is found, refer to OEM guidelines for repair or replacement of the 20-Way TCM Vehicle Harness Connector. Go to Step V

  • If no contamination or damage is found, Go to Step H

H

Purpose:Verify resistance of Vehicle Primary Data Link (J1939 A) at 20-Way TCM Vehicle Harness Connector.

  1. Key off.

  2. Measure resistance between 20-Way TCM Vehicle Harness Connector Pin 11 and Pin 12. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (8)

  3. Compare reading(s) in table.

  • If readings are out of range, refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939 A). Go to Step V

  • If readings are in range, Go to Step I

PinsRangeReading(s)
11 to 1250–70 Ohms

I

Purpose:Purpose: Verify fault code status.

  1. Key off.

  2. Reconnect all connectors and verify that all components are properly installed.

  3. Key on with engine off.

  4. Connect ServiceRanger.

  5. Retrieve and record the transmission fault codes, FMIs, occurrences, and timestamps.

  • If Fault Code 115 is Inactive, an intermittent wiring issue exists within the vehicle Primary Data Link (J1939 A), refer to OEM guidelines for repair or replacement. Go to Step V

  • If Fault Code 115 is Active and no fault was found with the vehicle Primary Data Link (J1939 A), replace the Transmission Control Module (TCM). Go to Step V

    Note: Troubleshooting indicates no fault found with the wiring or connections to the TCM. Ensure an intermittent issue does not exist with the wiring or connections.

J

Purpose:Verify Vehicle Primary Data Link (J1939 A) signal voltage.

  1. Key on with engine off.

  2. Measure voltage between 9-Way Diagnostic Connector Pin C and Pin A. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (9)

  3. Measure voltage between 9-Way Diagnostic Connector Pin D and Pin A. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (10)

  4. Record the total voltage by adding together the voltage readings.

  5. Compare reading(s) in table.

  • If readings are in range, Go to Step K

  • If readings are out of range, refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939 A). Go to Step V

PinsRangeReading(s)
C to AN/A
D to AN/A+
Total Voltage4.5–5.5 V=

K

Purpose:Verify resistance of Vehicle Primary Data Link (J1939 A).

  1. Key off.

  2. Measure resistance between 9-Way Diagnostic Connector Pin C and Pin D. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (11)

  3. Compare reading(s) in table.

  • If readings are out of range, refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939 A). Go to Step V

  • If readings are in range, Go to Step L

PinsRangeReading(s)
C to D50–70 Ohms

L

Purpose:Verify 20-Way TCM Vehicle Harness Connector condition.

  1. Key off.

  2. Disconnect the 20-Way TCM Vehicle Harness Connector.

  3. Inspect the 20-Way TCM Vehicle Harness Connector, verify the connector is free from contamination and corrosion; the terminals are not bent, spread or loose; and there is no damage to the connector body.

  4. Inspect the TCM side of the 20-Way TCM Vehicle Harness Connector, verify the connector is free from contamination and corrosion; the terminals are not bent, spread or loose; and there is no damage to the connector body.

  • If contamination or damage is found, refer to OEM guidelines for repair or replacement of the 20-Way TCM Vehicle Harness Connector. Go to Step V

  • If no contamination or damage is found, Go to Step M

M

Purpose:Verify resistance of Vehicle Primary Data Link (J1939 A) at 20-Way TCM Vehicle Harness Connector.

  1. Key off.

  2. Measure resistance between 20-Way TCM Vehicle Harness Connector Pin 11 and Pin 12. Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (12)

  3. 3.Compare reading(s) in table.

  • If readings are out of range, refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939 A). Go to Step V

  • If readings are in range, Go to Step N

PinsRangeReading(s)
11 to 1250–70 Ohms

N

Purpose:Verify fault code status.

  1. Key off.

  2. Reconnect all connectors and verify that all components are properly installed.

  3. Key on with engine off.

  4. Connect ServiceRanger.

  5. Retrieve and record the transmission fault codes, FMIs, occurrences, and timestamps.

  • If Fault Code 115 is Inactive, an intermittent wiring issue exists within the vehicle Primary Data Link (J1939 A), refer to OEM guidelines for repair or replacement. Go to Step V

  • If Fault Code 115 is Active and no fault was found with the vehicle Primary Data Link (J1939 A), replace the Transmission Control Module (TCM). Go to Step V

    Note: Troubleshooting indicates no fault found with the wiring or connections to the TCM. Ensure an intermittent issue does not exist with the wiring or connections.

O

Purpose:Verify resistance of the Vehicle Primary Data Link (J1939 A) at Engine ECU Vehicle Harness Connector.

  1. Key off.

  2. Locate and disconnect the Engine ECU vehicle harness connector containing the vehicle Primary Data Link (J1939 A).

    Note: Refer to OEM guidelines for Engine ECU vehicle harness connector location, connector removal, and J1939 High (+) and J1939 Low (-) connector pin locations.

  3. Measure resistance between Engine ECU vehicle harness connector Pin J1939 High (+) and Pin J1939 Low (-). Record reading in table.

    Primary Data Link (J1939 A) (TRTS0950) (13)

  4. Compare reading(s) in table.

  • If readings are out of range, refer to OEM guidelines for repair or replacement of vehicle Primary Data Link (J1939 A). Go to Step V

  • If readings are in range, Engine ECU has continuity to the vehicle Primary Data Link (J1939 A). A condition may exist with the following:

    • Power up issue with the Engine ECU
    • Fault message from the Engine ECU
    • Contact OEM for further diagnostic instructions. Go to Step V
PinsRangeReading(s)
J1939 High (+) to J1939 Low (-)50–70 Ohms

V

Purpose:Verify repair.

  1. Key off.

  2. Reconnect all connectors and verify that all components are properly installed.

  3. Key on with engine off.

  4. Connect ServiceRanger.

  5. Go to “Fault Codes”.

  6. Select “Clear All Faults”.

  7. Operate vehicle and attempt to reset the fault code or duplicate the previous complaint.

  8. Check for fault codes using ServiceRanger.

  • If no fault codes set and the vehicle operates properly, test complete.

  • If Fault Code 115 sets Active during operation, Go to Step A

  • If a fault code other than 115 sets Active, troubleshoot per the Fault Code Isolation Procedure Index

Primary Data Link (J1939 A) (TRTS0950) (2024)

References

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