U2139

Code

OPEL U — Network/User

CAN-Bus No Communication with CIM (Steering Column Module)

Brand: OPEL

Type: U — Network/User

Views: UK: 7 EN: 8 RU: 3

AI status

Completed

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Page language: EN

Causes

Open or short in CAN_H or CAN_L wiring to the CIM
Corroded/damaged connector or poor pin contact at the CIM
Loss of CIM supply power or ground(s)
Faulty CIM (internal failure)
Bus termination missing or shorted (incorrect resistance)
Network wiring shorted to battery or chassis ground

Symptoms

Steering column functions do not respond (wipers, stalks, horn, cruise, audio controls)
Instrument cluster or infotainment shows steering column/module communication fault
Vehicle may not recognize key / no crank or steering lock engagement problems
Multiple related CAN communication DTCs present
Intermittent or permanent loss of specific features controlled by CIM

What to check

Use a scan tool to read freeze frame data and confirm U2139 is present and current/confirmed
Check for other U-codes on gateway, instrument cluster, BCM and related modules
Verify battery voltage (12V nominal) and stable electrical supply
Visually inspect the CIM connector(s) for corrosion, bent pins, water intrusion or damage
Check fuses and direct power/ground at the CIM connector
Measure DC voltages at CAN_H and CAN_L on the CIM connector with key ON (expected idle common-mode ~2.5 V)

Signal parameters

CAN idle (recessive) common-mode voltage: ~2.5 V on both CAN_H and CAN_L
CAN dominant: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V)
Termination resistance (entire bus): ≈ 60 Ω (two 120 Ω resistors in parallel)
Typical body CAN baud rate: often 250 kbps or 500 kbps (verify vehicle-specific rate with scan tool)
No DC short to battery or chassis ground on either CAN_H or CAN_L

Diagnostic algorithm

Confirm code: connect a capable scan tool and confirm U2139 and any related codes; note time stamps and freeze frame.
Check basic power: verify battery voltage and inspect fuses/relays supplying the CIM. Verify proper power and ground pins at the CIM connector.
Visual inspection: remove covers and inspect wiring and connector for corrosion, bent pins, water, or physical damage.
Measure static CAN voltages: with ignition ON, measure CAN_H and CAN_L at the CIM connector. Compare to expected idle values (~2.5 V).
Measure termination: disconnect power and measure resistance across CAN_H and CAN_L at connector — expect ~60 Ω. If open or much lower, trace for missing/shorted terminators.
Scope the bus: use an oscilloscope to observe CAN waveform for noise, missing frames, wrong bit timing, dominant/recessive issues or stuck lines.
Isolate fault: if waveform or resistance indicates a short/short-to-ground, disconnect sections/modules (where serviceable) to isolate the segment causing the fault.
Check other modules: verify gateway/BCM communication and whether other modules see the CIM. Try to communicate with CIM via scan tool; if not present, it likely isn’t joining the bus.
Repair wiring/connector issues: repair or replace damaged wiring, pins, or connectors. Clean and apply dielectric grease to prevent corrosion if applicable.
Module level: if wiring and supply/ground are good but the CIM still does not communicate, check for available software updates or reprogramming. Replace the CIM only after wiring and network integrity are confirmed.
Clear codes and test: after repairs, clear codes, cycle ignition and road test. Re-scan to confirm U2139 does not return.

Likely causes

Corroded or loose connector at the steering column module
Open/short in CAN pair between gateway/body module and CIM
CIM not powered due to blown fuse or lost ground
Faulty CIM software/firmware or incorrect module coding
Damaged CAN termination resistor or wrong termination

Fault status

⚠️ Status

U2139 — CAN Bus No Communication with Steering Column Module (CIM). The CIM is not responding on the vehicle CAN network. Steering-column related functions may be unavailable. Inspect power/ground, connectors, CAN wiring, and module presence on the bus.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours

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