Code
U02A6
Generic
U — Network/User
Lost Communication With Safety Integration Control Module
Views:
UK: 10
EN: 17
RU: 8
AI status
Completed
Completed
100%
Causes
- Faulty Safety Integration Control Module (SICM)/SDM
- Open or short in CAN/LIN communication wiring
- Corroded, loose or damaged connector at the module
- Blown fuse or loss of module supply/ground
- Network termination or wiring short to battery/ground
- Intermittent battery/low voltage condition or poor battery connections
Symptoms
- Airbag/airbag light or SRS warning lamp illuminated
- Possible disablement of other safety features (seatbelt pretensioners, side curtain deployment)
- Stored communication-related DTCs in multiple modules
- No responses from the Safety Integration Control Module when scanned
- Intermittent or permanent loss of specific safety functions
What to check
- Retrieve all stored and pending DTCs from all modules with a capable scan tool and save freeze frame data
- Inspect battery voltage and battery connections; verify good charging system voltage (12.4–14.7 V during cranking/running)
- Visually inspect fuses and fusible links related to the restraint/SICM circuits
- Visually inspect the safety module connector for corrosion, bent pins, or water intrusion
- Check for other U0xxx/U1xxx communication codes in other modules that indicate wider bus issues
- Perform wiggle tests on harnesses while monitoring communications (use caution near airbag connectors)
Signal parameters
- CAN bus idle voltages: CAN High ≈ 2.5–3.5 V, CAN Low ≈ 1.5–2.5 V (nominal common-mode ≈ 2.5 V)
- Differential CAN voltage during activity: ±1 V typical (dominant ~2.5 V difference)
- Module awake/sleep states: expected periodic messages from SICM when key on (~several messages/sec)
- Message frequencies: verify expected LIN/CAN message IDs and frequency for safety module (refer to factory data)
- No response: absence of expected CAN IDs from SICM or CRC/frame errors on bus
Diagnostic algorithm
- Record all codes and freeze frame from this and other control modules. Note if SCCM/SICM is present in module list. 2) Verify good battery voltage and charging system. Recharge or provide stable power if battery low. 3) Inspect fuses and relays for restraint/SICM power; replace if blown and re-test. 4) Visually inspect module connector and harness for damage, corrosion, bent pins; repair as necessary. 5) Using a scan tool, confirm whether SICM appears on network (module list) and whether it returns data or communicates. 6) If module not present on bus, check for proper supply and ground at the module connector with key on (verify parasitic current only with service procedures). 7) Check CAN high/low voltages at the module connector with key on and engine off; compare to expected values. 8) Use an oscilloscope or high-speed CAN data logger to check signal quality, bus contention, and message frames; look for stuck-dominant conditions or excessive noise. 9) If bus is failing, isolate sections by disconnecting other modules one at a time (where serviceable) to find a shorted node or faulty module. 10) If wiring/connector repair found, repair and retest communications. 11) If wiring and power/ground are good and no other module causes the fault, suspect SICM internal failure—consult manufacturer data for module replacement, required programming, and SRS/airbag initialization procedures. 12) After repair, clear codes and verify functionality; perform any required restraint system self-tests and learn/calibration procedures per factory instructions.
Likely causes
- Disconnected or corroded connector at the safety module
- Failed module power or ground circuit (blown fuse, open ground)
- Damaged CAN high/low wiring or pinched harness near collision zones
- Faulty restraint module (internal failure)
- Another module on the same bus holding the network inactive
Fault status
Status
Safety Integration Control Module not responding on vehicle network (lost communication). Verify power, ground, connectors and CAN/LIN bus integrity.
Repair difficulty: Hard
Diagnostic time: 1.5-4.0 hours
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