B1C02

Code

Generic B — Body

Occupant Classification Sensor 2 Circuit Short to Ground

Brand: Generic

Type: B — Body

Views: UK: 7 EN: 7 RU: 8

AI status

Completed

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Page language: EN

Causes

Damaged wiring insulation with conductor contacting vehicle chassis ground
Corroded or bent connector pins at the OCS or occupancy ECU
Failed occupant classification sensor (pad/module)
Faulty Occupant Classification ECU / airbag control module
Water/moisture intrusion into seat or connector
Improper previous seat/airbag repairs or aftermarket seat components

Symptoms

Airbag warning lamp illuminated or airbag system disabled
Passenger airbag enable/disable indicator incorrect or inoperative
Seat belt reminder or occupant detection messages
Unable to calibrate or clear occupant classification system faults
Possible loss of seat heater/other seat electronics (if shared harness)

What to check

Read and record all stored DTCs and freeze frame data with a capable scan tool
Visually inspect seat wiring, connectors and harness routing for damage or pinching
Check connectors for corrosion, bent pins, tight fit and evidence of moisture
Backprobe OCS harness for reference voltage, signal and continuity to ECU
Wiggle test harness while watching live data to reproduce fault
Disconnect battery and inspect for previous repair splices or aftermarket wiring

Signal parameters

Reference/supply voltage to OCS typically ~5 V (manufacturer specific) with key ON; verify per vehicle service data
Signal voltage from OCS sensor varies with occupant load (0–5 V nominal range); short to ground commonly presents as ~0 V
Open circuit often shows no signal or floating voltage; short to battery shows near VBAT
Low resistance to chassis ground on the sensor signal/return (
Resistance of intact sensor elements typically measured in kΩ range — consult vehicle-specific spec

Diagnostic algorithm

Retrieve DTC(s), note freeze frame and clear codes. See if B1C02 returns immediately.
With ignition ON (engine off), monitor occupant classification sensor #2 live data/value using a scan tool while a helper sits in the passenger seat or applies a test weight.
Visually inspect the passenger seat (bottom and track area), connectors under the seat, and harness routing for chafing, pinched wires, corrosion or water damage.
Backprobe the OCS #2 signal wire and measure voltage vs. chassis ground. A reading near 0 V suggests a short to ground; compare to reference voltage and other OCS channels where applicable.
With battery disconnected, measure continuity between the OCS #2 signal conductor and chassis ground. Low resistance confirms short to ground. Also check continuity to airbag/occupant ECU pins per wiring diagram.
Disconnect the OCS connector at the sensor module. Re-check continuity from sensor-side harness conductor to ground. If short remains on harness side, repair wiring; if short disappears, suspect the sensor.
Inspect and repair any damaged insulation, replace corroded connectors, and secure harness away from seat metal edges. Use factory-style terminals and seals for replacements.
If wiring and connectors are good, swap or bench-test the OCS module (if service manual allows) or replace the sensor assembly and retest.
If fault persists after sensor replacement, inspect/replace the occupant classification ECU or airbag control module per manufacturer procedures and verify vehicle-specific programming/initialization.
After repairs, clear codes and verify that the DTC does not return and that occupant detection/airbag enable function is normal.

Likely causes

Chafed seat harness where it passes through seat frame contacting metal
Connector terminal corrosion at the seat bottom connector
Shorted sensor element inside the OCS pad due to foam contamination or water
Broken internal OCS wiring that is contacting seat frame ground
Defective occupant classification module reporting shorted input

Fault status

⚠️ Status

B1C02 - Occupant Classification Sensor 2 Circuit Short to Ground. Inspect seat wiring, connectors and sensor for short to chassis ground; possible sensor or module failure.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours