Code
U0140
OPEL
U — Network/User
CAN-Bus No Communication with CIM (Steering Column Module)
Views:
UK: 7
EN: 15
RU: 35
AI status
Completed
Completed
100%
Causes
- Faulty or disconnected Steering Column Module (CIM)
- Open, shorted or damaged CAN bus wiring between CIM and network
- Corroded/loose connector pins at CIM or intermediate connectors
- Blown fuse or loss of module power/ground
- Failed CAN transceiver inside CIM or other module causing bus error
- Missing or incorrect termination (open or shorted termination resistor)
Symptoms
- Steering column functions (e.g., steering wheel controls, column stalks) not working
- Instrument cluster or other modules show related errors or limp functionality
- Multiple communication-related fault codes present
- Certain driver-assist or convenience features inoperative
- Possible loss of immobilizer/lock/unlock or key recognition features
What to check
- Read and record all stored DTCs and freeze frame using a capable scan tool
- Verify battery voltage and charging system stability (engine OFF and cranking)
- Inspect fuses and relays related to the CIM power and ignition circuits
- Visually inspect connectors at the steering column and nearby junctions for corrosion, bent pins or water ingress
- Check that other modules on the same CAN network are present on the scanner
- Measure CAN bus voltages at the CIM connector: CAN_H, CAN_L and differential
Signal parameters
- CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V
- CAN bus dominant: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
- Termination resistor: ~60 Ω measured across CAN_H and CAN_L (two 120 Ω in parallel)
- Network data rate depends on vehicle (commonly 500 kb/s or 250 kb/s for body networks)—verify vehicle specification
- Expected: periodic messages/IDs from CIM visible on a capable bus monitor or oscilloscope
Diagnostic algorithm
- Confirm code and scan for other U-codes. Note time stamps and related faults.
- Check battery voltage and main power fuses/relays for the CIM. Repair any power/ground issues.
- Perform visual inspection of steering column connector, harness, and any splice/junctions for damage or corrosion; repair as needed.
- With ignition ON, use a scan tool to check whether CIM appears on the network. If not present, proceed to physical checks.
- Measure CAN_H and CAN_L at the CIM connector. If voltages are shorted to battery or ground, trace and repair short.
- With vehicle power off, measure termination resistance across CAN_H and CAN_L at a convenient junction. Replace faulty termination or open circuits.
- If voltages and termination are correct, monitor the bus with oscilloscope or bus analyzer while cycling ignition and operating steering column controls to look for transients or missing frames.
- Disconnect other modules one at a time (if safe and practical) or isolate segments to identify if a different module is pulling the bus down.
- If wiring and bus integrity are good but CIM still not communicating, try reprogramming/rebooting the CIM per manufacturer procedure (if available) before replacing.
- If confirmed CIM hardware failure, replace module and reconfigure/program as required. Clear codes and verify repair by confirming normal CAN traffic and restoration of functions.
Likely causes
- Loose or corroded connector at the steering column module
- CAN_H or CAN_L short to ground or battery on the steering column harness
- Damaged wiring harness between CIM and nearest gateway/module
- Failed CIM transceiver or internal CIM failure
- Blown fuse supplying power to CIM or missing ground
Fault status
Status
No communication received from Steering Column Module (CIM) on CAN bus.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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