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Multi-Plex Control System (Diagnostic Codes): Diagnosis Honda Civic IX

Communication Devices 12 illustrations ~1704 words

DTC U128D: Immobilizer-Keyless Control Unit Lost Communication With Gauge Control Module

Note. If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A.

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Scheme 150: DTC U128D: Immobilizer-Keyless Control Unit Lost Communication With Gauge Control Module
Scheme 150: DTC U128D: Immobilizer-Keyless Control Unit Lost Communication With Gauge Control Module

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  1. Problem verification: 1. Clear the DTCs with the HDS. 2. Turn the ignition switch to LOCK (0) and then back to ON (II). 3. Wait for at least 6 seconds. 4. Check for DTCs with the HDS. Is DTC U128D indicated? YES: Go to step 2. NO: Intermittent failure, the system is OK at this time. Check for loose or poor connections.
  2. Determine possible failure area (gauge control module (tach) power and ground, B_CAN line): 1. Select B-CAN CONTROL UNITS INFORMATION from the BODY ELECTRICAL SYSTEM SELECT menu, and then select CHECK CONNECTED CONTROL UNITS. 2. Check the DETECT/NOT AVAILABLE information of the GAUGE CONTROL MODULE. Is DETECT indicated? YES: Go to step 7 . NO: Go to step 3.
  3. Fuse check: 1. Check the following fuse. Fuse No. A29 (10 A) Location Under-hood fuse/relay box Is the fuse OK? YES: Go to step 4. NO: Replace the fuse. If the fuse blows again, repair a short to ground in the No. A29 (10 A) fuse circuit.
  4. Open wire check (+B_BACK_UP line): 1. Turn the ignition switch to LOCK (0). 2. Disconnect the following connector. Gauge control module (tach) 32P connector 3. Measure the voltage between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Test circuit +B_BACK_UP Test point 1 Gauge control module (tach) 32P connector No. 1 (WHT) Test point 2 Body ground Is there battery voltage? YES: Go to step 5. NO: Repair an open or high resistance in the wire.
  5. Open wire check (GND lines): 1. Check for continuity between test points 1 and 2 individually. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Test circuit GND Test point 1 Gauge control module (tach) 32P connector No. 4 (BLK) Test point 2 Body ground Test circuit GND Test point 1 Gauge control module (tach) 32P connector No. 32 (BRN) Test point 2 Body ground Is there continuity? YES: Go to step 6. NO: Repair an open or high resistance in the ground wire or poor ground (G502/G503).
  6. Open wire check (B_CAN lines): 1. Disconnect the following connector. Immobilizer-keyless control unit 7P connector 2. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Immobilizer-keyless control unit 7P connector: disconnected Test circuit B_CAN-H Test point 1 Immobilizer-keyless control unit 7P connector No. 4 (PNK) Test point 2 Gauge control module (tach) 32P connector No. 30 (PNK) Is there continuity? YES: An open or poor connection in the B_CAN-L wire between the immobilizer-keyless control unit and the gauge control module (tach). NO: An open or poor connection in the B_CAN-H wire between the immobilizer-keyless control unit and the gauge control module (tach).
  7. Open wire check (B_CAN lines): 1. Turn the ignition switch to LOCK (0). 2. Disconnect the following connectors. Gauge control module (tach) 32P connector Immobilizer-keyless control unit 7P connector 3. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Immobilizer-keyless control unit 7P connector: disconnected Test circuit B_CAN-H Test point 1 Immobilizer-keyless control unit 7P connector No. 4 (PNK) Test point 2 Gauge control module (tach) 32P connector No. 30 (PNK) Is there continuity? YES: An open or poor connection in the B_CAN-L wire between the immobilizer-keyless control unit and the gauge control module (tach). NO: An open or poor connection in the B_CAN-H wire between the immobilizer-keyless control unit and the gauge control module (tach).

DTC U128D: Information Display Unit Lost Communication With Gauge Control Module

Note. If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A.

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Scheme 153: DTC U128D: Information Display Unit Lost Communication With Gauge Control Module
Scheme 153: DTC U128D: Information Display Unit Lost Communication With Gauge Control Module

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Scheme 157
  1. Problem verification: 1. Clear the DTCs with the HDS. 2. Turn the ignition switch to LOCK (0) and then back to ON (II). 3. Wait for at least 6 seconds. 4. Check for DTCs with the HDS. Is DTC U128D indicated? YES: Go to step 2. NO: Intermittent failure, the system is OK at this time. Check for loose or poor connections.
  2. Determine possible failure area (gauge control module (tach) power and ground, B_CAN line): 1. Select B-CAN CONTROL UNITS INFORMATION from the BODY ELECTRICAL SYSTEM SELECT menu, and then select CHECK CONNECTED CONTROL UNITS. 2. Check the DETECT/NOT AVAILABLE information of the GAUGE CONTROL MODULE. Is DETECT indicated? YES: Go to step 7 . NO: Go to step 3.
  3. Fuse check: 1. Check the following fuse. Fuse No. A29 (10 A) Location Under-hood fuse/relay box Is the fuse OK? YES: Go to step 4. NO: Replace the fuse. If the fuse blows again, repair a short to ground in the No. A29 (10 A) fuse circuit.
  4. Open wire check (+B_BACK_UP line): 1. Turn the ignition switch to LOCK (0). 2. Disconnect the following connector. Gauge control module (tach) 32P connector 3. Measure the voltage between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Test circuit +B_BACK_UP Test point 1 Gauge control module (tach) 32P connector No. 1 (WHT) Test point 2 Body ground Is there battery voltage? YES: Go to step 5. NO: Repair an open or high resistance in the wire.
  5. Open wire check (GND lines): 1. Check for continuity between test points 1 and 2 individually. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Test circuit GND Test point 1 Gauge control module (tach) 32P connector No. 4 (BLK) Test point 2 Body ground Test circuit GND Test point 1 Gauge control module (tach) 32P connector No. 32 (BRN) Test point 2 Body ground Is there continuity? YES: Go to step 6. NO: Repair an open or high resistance in the ground wire or poor ground (G502/G503).
  6. Open wire check (B_CAN lines): 1. Disconnect the following connector. Information display unit 12P connector 2. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Information display unit 12P connector: disconnected Test circuit B_CAN-H Test point 1 Gauge control module (tach) 32P connector No. 30 (PNK) Test point 2 Information display unit 12P connector No. 9 (PNK) Is there continuity? YES: An open or poor connection in the B_CAN-L wire between the information display unit and the gauge control module (tach). NO: An open or poor connection in the B_CAN-H wire between the information display unit and the gauge control module (tach).
  7. Open wire check (B_CAN lines): 1. Turn the ignition switch to LOCK (0). 2. Disconnect the following connectors. Gauge control module (tach) 32P connector Information display unit 12P connector 3. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Information display unit 12P connector: disconnected Test circuit B_CAN-H Test point 1 Gauge control module (tach) 32P connector No. 30 (PNK) Test point 2 Information display unit 12P connector No. 9 (PNK) Is there continuity? YES: An open or poor connection in the B_CAN-L wire between the information display unit and the gauge control module (tach). NO: An open or poor connection in the B_CAN-H wire between the information display unit and the gauge control module (tach).

DTC U128D: MICU Lost Communication With Gauge Control Module

Note. Refer to the Electrical Wiring Diagrams for the location of the under-dash fuse/relay box connectors. If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A.

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Scheme 158: DTC U128D: MICU Lost Communication With Gauge Control Module
Scheme 158: DTC U128D: MICU Lost Communication With Gauge Control Module

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  1. Problem verification: 1. Clear the DTCs with the HDS. 2. Turn the ignition switch to LOCK (0) and then back to ON (II). 3. Wait for at least 6 seconds. 4. Check for DTCs with the HDS. Is DTC U128D indicated? YES: Go to step 2. NO: Intermittent failure, the system is OK at this time. Check for loose or poor connections.
  2. Fuse check: 1. Check the following fuse. Fuse No. A29 (10 A) Location Under-hood fuse/relay box Is the fuse OK? YES: Go to step 3. NO: Replace the fuse. If the fuse blows again, repair a short to ground in the No. A29 (10 A) fuse circuit.
  3. Open wire check (+B_BACK_UP line): 1. Turn the ignition switch to LOCK (0). 2. Disconnect the following connector. Gauge control module (tach) 32P connector 3. Measure the voltage between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Test circuit +B_BACK_UP Test point 1 Gauge control module (tach) 32P connector No. 1 (WHT) Test point 2 Body ground Is there battery voltage? YES: Go to step 4. NO: Repair an open or high resistance in the wire.
  4. Open wire check (GND lines): 1. Check for continuity between test points 1 and 2 individually. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Test circuit GND Test point 1 Gauge control module (tach) 32P connector No. 4 (BLK) Test point 2 Body ground Test circuit GND Test point 1 Gauge control module (tach) 32P connector No. 32 (BRN) Test point 2 Body ground Is there continuity? YES: Go to step 5. NO: Repair an open or high resistance in the ground wire or poor ground (G502/G503).
  5. Open wire check (B_CAN lines): 1. Disconnect the following connector. Under-dash fuse/relay box connector K (12P) 2. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) Gauge control module (tach) 32P connector: disconnected Under-dash fuse/relay box connector K (12P): disconnected Test circuit B_CAN-H Test point 1 Under-dash fuse/relay box connector K (12P) No. 2 (PNK) Test point 2 Gauge control module (tach) 32P connector No. 30 (PNK) Is there continuity? YES: An open or poor connection in the B_CAN-L wire between the MICU and the gauge control module (tach). NO: An open or poor connection in the B_CAN-H wire between the MICU and the gauge control module (tach).

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