B2121

Code

Generic B — Body

Driver Seat Belt Pretensioner Circuit Fault

Brand: Generic

Type: B — Body

Views: UK: 29 EN: 80 RU: 33

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Page language: EN

Causes

Open circuit in pretensioner wiring (broken wire, disconnected connector)
Short to ground or battery (wiring pinched, chafed insulation)
High resistance in circuit (corroded connector, poor crimp)
Faulty driver seat belt pretensioner (squib)
Damaged or faulty clockspring/steering column harness (if pretensioner routing uses it)
Seat module or airbag/SRS control module fault

Symptoms

SRS/airbag warning lamp illuminated on dash
Possible passive seat belt/pretensioner warning (if equipped)
Front airbags may be suppressed or system placed in a reduced-protection state
Intermittent SRS light if wiring intermittently shorts or opens
Vehicle may fail SRS system self-test or diagnostic readiness

What to check

Read and record all stored SRS/airbag fault codes and freeze-frame data with a capable scan tool
Visually inspect driver seat and under-seat area for damaged connectors, aftermarket equipment, or signs of impact/repair
Inspect pretensioner connector for corrosion, bent pins, burn marks or water intrusion
Check wiring routing from pretensioner to SRS module for chafing, pinched sections or broken insulation
Confirm vehicle has not had an incomplete airbag deployment repair (missing or incorrect components)
Note: always follow manufacturer-required battery disconnect and SRS safe procedures before touching pretensioner wiring or connectors

Signal parameters

Pretensioner coil resistance (typical, varies by vehicle): roughly 0.5–5 ohms — infinite = open; ~0 ohm = hard short
Open-circuit condition: OL or infinite resistance between pretensioner terminals
Short-to-ground/power: near 0 ohms between pretensioner circuit and chassis ground or battery positive
Module input: SRS module monitors current/impedance; fault set when measured impedance falls outside manufacturer-defined thresholds
Scan-tool live data may show driver pretensioner circuit status (OK, Open, Short, High Resistance)

Diagnostic algorithm

Read and record SRS codes and freeze-frame with an airbag-capable scan tool; note any related codes
Follow safety: disable battery negative and wait the manufacturer-specified time before disconnecting SRS connectors or working on pretensioner wiring
Perform visual inspection of driver pretensioner connector, wiring, seat rails and under-seat area for damage, corrosion or aftermarket modifications
Disconnect driver pretensioner connector and measure resistance across pretensioner terminals; compare to OEM specification (typical 0.5–5 Ω). Infinite indicates open; near 0 indicates short
With connector disconnected, check continuity of harness from pretensioner connector back to SRS module connector; repair any open circuits
Check for short to ground/power by measuring resistance from each pretensioner pin to chassis ground and to battery positive; low resistance indicates a short
Inspect and test clockspring (if circuit routes through steering column) per service manual; replace if intermittent or out-of-spec
Inspect SRS module connector pins and wiring at the module; wiggle test with scan tool connected to check for intermittent faults
If pretensioner is open or shorted, replace pretensioner and any damaged wiring/connectors; if clockspring or module is faulty, follow OEM replacement procedures
After repairs, clear codes, perform SRS system self-test and verify no new SRS faults. If deployment occurred previously, follow manufacturer rules for module/pretensioner replacement and occupant protection system integrity