What it means
B0065 denotes an electrical fault in the left-front (driver) seat-belt pretensioner circuit. Factory diagnostics list specific set conditions—for example, the SDM detects pretensioner-LF high-control < 2.4 V under certain enable criteria, or interprets open/high resistance or shorts in the LF pretensioner circuits. Charm+1
Symptoms
- SRS indicator on; LF pretensioner inhibited until the fault is corrected. Charm
Severity / priority
High (safety-critical). A disabled pretensioner reduces restraint performance in a crash. Charm
Common causes
- Open/high resistance in the LF pretensioner wiring, damaged conductors, poor terminal tension.
- Short-to-ground/short-to-voltage in the LF high/low control circuits.
- Connector shorting-bar issues at the pretensioner; several OEM notes explain how shorting bars can tie high/low together if mis-positioned. Charm+1
Diagnostic notes
- Confirm with an SRS-capable scan tool; follow all SRS handling precautions.
- Inspect harness paths (under seat, IP, door pass-throughs); an OEM service bulletin directs rear side-door harness replacement when certain pretensioner DTCs (including B0065) are present—use the bulletin by VIN/applicability. NHTSA
- Perform pinpoint tests for open/high resistance and short-to-GND/B+; verify connector shorting-bar operation. Some platforms have shared connectors that affect both pretensioners (e.g., C202 under the glovebox on GMT platform). Charm+1
Possible fixes
- Repair/replace damaged wiring/terminals; correct routing and strain relief.
- Replace the LF pretensioner if it fails OEM electrical checks.
- Where applicable, replace the affected door/seat harness per TSB; clear codes and re-verify. NHTSA
Primary sources: GM service-manual extracts for B0065 (set conditions and diagnostics), OEM TSB covering pretensioner-related DTCs including B0065 (harness replacement), and OEM/practitioner notes on pretensioner connector shorting bars and shared connectors. GMTNation+4Charm+4Charm+4