Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC U128D (Keyless Access Backup Control Unit)
DTC U128D : Backup control unit lost communication with gauge control module
| DTC Description | DTC |
|---|---|
| U128D Backup control unit lost communication with gauge control module |
DTC (Backup Control Unit)
NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A .
- Problem verification
-1. Clear the DTCs with the HDS.
Clear DTCs
-2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.
-3. Wait for at least 6 seconds.
-4. Check for DTCs with the HDS.
DTC Description DTC U128D Backup control unit lost communication with gauge control module 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.
- Open wire check (B-CAN_H, B-CAN_L lines)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the receiving control unit connector.
Keyless access/TPMS control unit connector C (20P) -3. Disconnect the transmitting control unit connectors.
Gauge control module 32P connector -4. Check for continuity between the receiving control unit and the transmitting control unit on the B-CAN_H circuit and the B-CAN_L circuit as specified in the table while in the vehicle OFF (LOCK) mode.
DTC CIRCUIT NAME RECEIVING CONTROL UNIT TRANSMITTING CONTROL UNIT U128D B-CAN_H Keyless access/TPMS control unit connector C (20P) No. 1 Gauge control module 32P connector No. 26 B-CAN_L Keyless access/TPMS control unit connector C (20P) No. 11 Gauge control module 32P connector No. 27 Is there continuity?
YES
The B-CAN_L to B-CAN_H wire is OK. Go to step 3.
NO
Repair an open or high resistance in the wire(s).
- Determine possible failure area (the receiving control unit or the transmitting control unit)
-1. Reconnect all connectors.
-2. Clear the DTCs with the HDS.
Clear DTCs
-3. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.
-4. Wait for at least 6 seconds.
-5. Check for DTCs with the HDS.
DTC Description DTC U128D Backup control unit lost communication with gauge control module Is DTC U128D indicated?
YES
Check for loose terminals and poor connections in the keyless access/TPMS control unit connector. Check is OK, replace the keyless access/TPMS control unit .
NO
The keyless access/TPMS control unit is OK at this time. Replace the transmitting control unit.
(Refer to the DTC code shown on the display, and then replace the control unit based on the instructions in the chart below.)
DTC TRANSMITTING CONTROL UNIT U128D Replace the gauge control module
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.