U0154

Code

Generic U — Network/User

Lost Communication With Restraints Occupant Classification System Module

Brand: Generic

Type: U — Network/User

Views: UK: 45 EN: 197 RU: 46

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Blown fuse or lost power to the OCS module
Poor or missing ground connection for the OCS module
Damaged or disconnected module wiring or connector
Corroded or water-damaged connector at the OCS module
Faulty OCS module (internal failure)
Faults or interruptions on the vehicle CAN/communication bus

Symptoms

Airbag / SRS warning lamp illuminated or flashing
Seat occupant detection not functioning (seatbelt reminders incorrect)
No display or incorrect occupant classification on service tool
Other network modules report lost communication or related U-codes
Possible disablement of passenger airbag deployment logic

What to check

Use a capable scan tool to read all stored U and B codes and verify U0154 presence and freeze frame
Confirm whether the OCS module appears on the vehicle network (module list / ID) with scan tool
Check battery voltage (12.2–14.8 V) and battery condition before diagnosis
Inspect fuses and fusible links related to restraints/OCS power
Visually inspect harness and connector at the OCS module and seat (look for water, corrosion, damage)
Wiggle test harness while monitoring communication status to reproduce intermittent faults

Signal parameters

CAN bus idle common-mode ~2.5 V; CANH ~2.5 V, CANL ~2.5 V with ignition off
Differential CAN amplitude typically ~2.5 V peak-to-peak during activity
Expected CAN bus message rate from OCS: periodic heartbeat (varies by manufacturer, typically 1–10 Hz)
Module should respond to diagnostic requests when wake/IGN on
Power supply at OCS pin: battery voltage present with key ON (approx. 12 V)
Ground continuity to chassis ground (low ohms)

Diagnostic algorithm

Record all DTCs and freeze-frame data with a full-function scan tool. Note related U-codes and B-codes.
Confirm battery voltage is within spec. Recharge or connect a stable power source if low.
Attempt to communicate with the OCS module using the scan tool. Note whether the module is detected and any module response errors.
Inspect and secure the OCS module connector and seat harness. Look for corrosion, bent pins, water intrusion, or physical damage.
Check fuses and power supply to the OCS module. Verify key ON voltage at the module power pins and good chassis ground at ground pins.
If connectors look good, perform a wiggle/strain test while monitoring module presence; this can reveal intermittent wiring faults.
Evaluate the vehicle CAN bus: verify bus speed, observe message frames, and inspect the CANH/CANL waveforms for noise, reflections, or missing termination using an oscilloscope or CAN tool.
Check continuity and resistance of CAN high/low between OCS and gateway/BCM and verify termination resistances (~60 ohms total across CANH-L) when bus awake.
If wiring and bus are intact but the module does not respond, verify whether the BCM/gateway is blocking communication or requires configuration. Check for software updates or reprogramming requirements.
If confirmed faulty, replace the OCS module with a correct part number and perform required coding/programming per manufacturer procedure. Clear codes and perform self-tests.
After repair, verify system operation: confirm OCS presence on the network, clear DTCs, perform diagnostic tests, and road-test to ensure no reoccurrence.
Safety note: Restraints system work may be hazardous. Follow vehicle manufacturer procedures and disconnect battery per safety guidelines when required. Refer airbag service work to qualified technicians if unsure.