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    Diagnostic Trouble Codes (DTC) : DTC U0032 (Previously U1301) J1850 (Class 2) Serial Data Communication Link High

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    luis eduardo corzo enriquez

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    Diagnostic Trouble Codes (DTC) : DTC U0032 (Previously U1301) J1850 (Class 2) Serial Data Communication Link High

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    luis eduardo corzo enriquez
    224 views3 pages

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    U0032

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    224 views3 pages

    Diagnostic Trouble Codes (DTC) : DTC U0032 (Previously U1301) J1850 (Class 2) Serial Data Communication Link High

    Uploaded by

    luis eduardo corzo enriquez

    Copyright:

    © All Rights Reserved
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    ALLISON 1000 AND 2000 PRODUCT FAMILIES ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

    DIAGNOSTIC TROUBLE CODES (DTC)

    DTC U0032 (Previously U1301) J1850 (Class 2) Serial Data Communication Link High

    TCM
    J1 HARNESS CONNECTOR
    (GRAY)

    J1850 PCM OR ECM


    POWERTRAIN CONTROLLER MODULE
    ENGINE CONTROLLER MODULE
    TCM

    J1850
    PCM
    or
    ECM
    130
    : J1-30
    - CLASS II
    J1850
    DATA LINK

    V07481.01.00

    Circuit Description

    Applications that employ J1850 class 2 serial communication use wire 130 to send operational information and
    commands among the various control modules. Included modules would be Powertrain Control Module (PCM),
    Antilock Brake System (ABS) Controller, Truck Body Controller {TBC), and Instrument Panel Cluster (IPC). Each
    controller sends out a state of health (SOH) message approximately once every second. The TCM uses these SOH
    messages to monitor the condition of the devices on the class 2 serial link.

    Conditions for Running the DTC

    • The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater
    than 18V and less than 32V (24V TCM).

    Conditions for Setting the DTC

    OTC U0032 is set when high voltage is detected on the class 2 data circuit for more than 3 seconds. This would
    normally indicate a short-to-power at wire 130.

    Action Taken When the DTC Sets

    • The CHECK TRANS light does not illuminate.

    • OTC U0032 is stored in the TCM history.

    • TCM uses default values for missing/erroneous information.

    • The TCM freezes shift adapts (DNA).

    Copyright© 2004 General Motors Corp. 5-247


    ALLISON 1000 AND 2000 PRODUCT FAMILIES ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

    DIAGNOSTIC TROUBLE CODES (DTC)


    Conditions for Clearing the DTC/CHECKTRANS Light
    A Scan Tool may be used to clear the code from the TCM history. The TCM automatically clears the OTC from the
    TCM history if the vehicle completes 40 warm-up cycles without the OTC recurring. The TCM self-clears this OTC
    when software detects a failure recovery has occurred.

    Diagnostic Aids
    • If communication can be established with the Scan Tool at the OBDII connector, then the U0032 should be
    shown in failure records only. This may indicate that an intermittent short-to-power was present at one time.
    Refer to Appendix A-Identification of Potential Circuit Problems.
    • It is not possible to communicate with J1850 with this OTC active.
    • Use the J 43890 T-harness to communicate with the TCM to determine if the U0032 is still active.
    • U0032 in failure records may be present along with a U1OOO-U1096 that is active. This would indicate that the
    malfunction occurred when the ignition was ON.
    • This code indicates that voltage is high at wire 130. Normally, this is an indication that a short-to-power exists
    at wire 130. Inspect wire 130 for this condition.
    • Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
    A bent terminal.
    A backed-out terminal.
    A damaged terminal.
    Poor terminal tension.
    A chafed wire.
    A broken wire inside the insulation.
    • When this OTC is active an engine no-start condition may exist. Class 2 messages will not be sent to enable
    the fuel pump and starter.

    Test Description
    The numbers below refer to the step numbers on the diagnostic table.
    2. This step checks engine data.
    3. This step tests for shorts or opens at wire 130.

    DTC U0032 J1850 (Class 2) Serial Data Communication Link High


    Step Action Yes No
    1 Was the Beginning The Troubleshooting Process Go to Step 2 Go to
    (Paragraph 5-4A) performed? Beginning The
    Troubleshooting
    Process
    (Paragraph 5-4A)
    2 1. Install the Scan Tool. Go to Diagnostic Go to Step 3
    2. Turn the ignition ON, with the engine OFF. Aids
    3. Verify engine data is being communicated via J1850.
    NOTE: U0032 is set when high voltage is detected on
    the J1850 serial communication link by the TCM for a
    time exceeding 3 seconds. This may indicate a short-
    to-power exists at wire 130.
    Is the engine data communicated to the Scan Tool?

    5-248 Copyright© 2004 General Motors Corp.


    ALLISON 1000 AND 2000 PRODUCT FAMILIES ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

    DIAGNOSTIC TROUBLE CODES (DTC)

    DTC U0032 J1850 (Class 2) Serial Data Communication Link High (cont'd)
    Step Action Yes No
    3 Inspect wire 130 for possible short-to-power. Go to Step 4 Go to Step 5
    Did you find a problem?
    4 NOTE: The vehicle OEM has responsibility for all Go to Step 6 -
    external wiring harness repair. Harness repairs
    performed by Allison Transmission distributors and
    dealers are not covered by Allison Transmission
    warranty.
    Repair the vehicle wiring harness.
    Is the repair complete?
    5 Switch the current TCM with a known good unit. Check for Go to Step 6 -
    proper communication. If this repairs the condition, reinstall
    the "defective" TCM to verify the TCM failure and then
    install a new TCM.
    Is replacement complete?
    6 In order to verify your repair: Begin the System OK
    1. Inspect the Scan Tool. diagnosis again.
    2. Clear the DTC. Go to Step 1
    Did the DTC return?

    Copyright© 2004 General Motors Corp. 5-249

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