U01BE

Code

Generic U — Network/User

Lost Communication with Drive Motor A Clutch Actuator

Brand: Generic

Type: U — Network/User

Views: UK: 25 EN: 36 RU: 26

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Page language: EN

Open or shorted CAN bus wiring (CAN High/CAN Low) between controller and actuator
Poor or corroded connector(s) at the actuator or harness splice
Failed clutch actuator module or internal transceiver
Loss of power or ground to the actuator (blown fuse, relay, loose ground)
Faulty vehicle control module (ECM/TCM) or CAN transceiver
Network termination or wiring short between bus branches

Retrieve all current and pending U-codes with a capable OBD-II scanner and record freeze-frame/UID data
Check for multiple network device failures or a network-wide loss of communication
Visually inspect connectors and harness for corrosion, damage, water ingress, or pins pushed out
Verify fuses and relays supplying power to the actuator and associated control modules
Measure battery voltage at the actuator power pin with key on; verify a good ground
Check CAN bus physical layer: measure CAN_H and CAN_L voltages at the actuator connector with ignition ON

CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each line around 2.5 V when recessive)
CAN dominant state voltages (during activity): CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
Typical CAN bus termination resistance: ~60 ohms measured between CAN_H and CAN_L at wake state (two 120 Ω in parallel)
Common bus data rates: 250 kb/s or 500 kb/s (verify vehicle-specific rate)
Expected live-data response: Drive Motor A actuator should provide regular status/heartbeat messages at defined intervals (check OEM message timing)

Read and record all network and related codes; note time, freeze frame, and occurrence conditions.
Check for broad network issues: verify other modules are communicating. If many U-codes exist, start with main gateway/connectors and battery voltage.
Visually inspect the actuator connector and wiring; repair any corrosion, pins out of position, or obvious damage.
Verify power and ground at the actuator with a digital multimeter (key ON). Replace blown fuses/relays as required.
With key ON, measure CAN_H and CAN_L at the actuator connector. Confirm idle and active voltages match expected ranges and that termination resistance is ~60 Ω.
If voltages look abnormal, isolate and repair short/open on CAN or power/ground wiring. Perform continuity tests back to the nearest splice or module.
If physical layer checks are good, use an oscilloscope or CAN bus analyzer to capture messages and confirm whether the actuator is transmitting or receiving messages/heartbeats.
If the actuator does not appear on the bus but has correct power/ground and wiring, bench-test or substitute a known-good actuator (if available) to confirm module failure.
If replacement actuator fixes communication, program/configure as required and clear codes. If not, evaluate upstream controller (ECM/TCM/gateway) and replace or repair as directed by further diagnostics.
After repair, clear codes, perform functional tests and a road test to verify normal operation and that the code does not return.