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DTC Troubleshooting: U128D
DTC U128D: MICU Lost Communication With Gauge Control Module
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DTC Description |
DTC |
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U128D MICU Lost Communication With Gauge Control Module |
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NOTE: Refer to the Electrical Wiring Diagrams for the location of the under-dash fuse/relay box connectors.
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1. |
Problem verification:
Problem verification
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?1. |
Clear the DTCs with the HDS.
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?2. |
Turn the ignition switch to LOCK (0) and then back to ON (II), or press the engine start/stop button to select the OFF mode and then the ON mode. |
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?3. |
Wait for at least 6 seconds. |
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?4. |
Check for DTCs with the HDS.
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DTC Description |
DTC |
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U128D MICU Lost Communication With Gauge Control Module |
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Is DTC U128D indicated?
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Intermittent failure, the system is OK at this time. Check for loose or poor connections.? |
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2. |
Fuse check:
Fuse check
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?1. |
Check the following fuses.
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Fuse |
No. A21 (10 A) |
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Location |
Under-hood fuse/relay box | |
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Fuse |
No. B5 (7.5 A) |
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Location |
Under-dash fuse/relay box | |
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Is each fuse OK?
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Replace the fuse. If the fuse blows again, repair a short to ground in the No. A21 (10 A) and/or the No. B5 (7.5 A) fuse circuit(s).? |
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3. |
Open wire check (+B BACK UP line):
Open wire check (+B BACK UP line)
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?1. |
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode. |
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?2. |
Disconnect the following connector.
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?3. |
Measure the voltage between test points 1 and 2.
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Test condition |
IG LOCK (0) or OFF mode
Gauge control module connector A (32P): disconnected |
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Test circuit |
+B BACK UP |
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Test point 1 |
Gauge control module connector A (32P) No. 1 (WHT) |
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Test point 2 |
Body ground | |
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Is there battery voltage?
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The +B BACK UP wire is OK. Go to step 4. |
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Repair an open or high resistance in the wire.? |
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4. |
Open wire check (IG1 METER line):
Open wire check (IG1 METER line)
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?1. |
Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode. |
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?2. |
Measure the voltage between test points 1 and 2.
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Test condition |
IG ON (II) or ON mode
Gauge control module connector A (32P): disconnected |
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Test circuit |
IG1 METER |
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Test point 1 |
Gauge control module connector A (32P) No. 17 (BRN) |
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Test point 2 |
Body ground | |
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Is there battery voltage?
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The IG1 METER wire is OK. Go to step 5. |
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Repair an open or high resistance in the wire.? |
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5. |
Open wire check (GND lines):
Open wire check (GND lines)
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?1. |
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode. |
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?2. |
Check for continuity between test points 1 and 2 individually.
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Test condition |
IG LOCK (0) or OFF mode
Gauge control module connector A (32P): disconnected |
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Test circuit |
GND |
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Test point 1 |
Gauge control module connector A (32P) No. 4 (BRN) |
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Test point 2 |
Body ground | |
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Test circuit |
GND |
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Test point 1 |
Gauge control module connector A (32P) No. 32 (BRN) |
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Test point 2 |
Body ground | |
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Is there continuity?
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The GND wires are OK. Go to step 6. |
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Repair an open or high resistance in the ground wire or poor ground (G502).? |
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6. |
Open wire check (B CAN lines):
Open wire check (B CAN lines)
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?1. |
Disconnect the following connector.
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?2. |
Check for continuity between test points 1 and 2.
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Test condition |
IG LOCK (0) or OFF mode
Gauge control module connector A (32P): disconnected
Under-dash fuse/relay box connector R (16P): disconnected |
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Test circuit |
B CAN-H |
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Test point 1 |
Under-dash fuse/relay box connector R (16P) No. 10 (PNK) |
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Test point 2 |
Gauge control module connector A (32P) No. 30 (PNK) | |
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Is there continuity?
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An open or poor connection in the B CAN-L wire between the MICU and the gauge control module.? |
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An open or poor connection in the B CAN-H wire between the MICU and the gauge control module.? | |