Code
B0086
HUMMER
B — Body
Supplemental Deployment Loop #2 Resistance Low
AI status
Completed
Completed
100%
Causes
- Short to ground in the deployment loop wiring
- Damaged, chafed, or pinched harness conductor
- Corroded, pushed-out, or poorly seated connector pins
- Faulty airbag squib or pretensioner with abnormally low resistance
- Poor repair/incorrect connector reassembly after previous work
- Internal short in the SRS (SDM) module (less common)
Symptoms
- SRS / airbag warning lamp illuminated on instrument cluster
- Diagnostic trouble code B0086 stored in SRS module
- Possible disabling of associated airbag/pretensioner circuit
- No immediate drivability effects, but increased risk that the related restraint will not deploy in a crash
- Related SRS messages or other SRS codes may be present
What to check
- Read SRS codes and freeze-frame data using a capable scan tool; note any additional SRS codes
- Visually inspect wiring harness routing along seat tracks, door hinges, floor, and under seats for damage
- Inspect connectors at the SRS module, affected airbag/pretensioner, and intermediate connectors for corrosion, bent pins, or moisture
- With vehicle service manual procedures followed (battery disconnected and required SRS discharge/wait time), measure resistance of the deployment loop with an ohmmeter
- Check for short to ground by measuring continuity between the deployment circuit and chassis ground (after safety precautions)
- Verify that no aftermarket accessories or recent repairs have disturbed the airbag wiring
Signal parameters
- Monitored parameter: loop resistance of supplemental deployment circuit #2
- Low-resistance condition: measured resistance significantly below manufacturer specification (approaching 0 Ω indicates a short)
- Normal condition: resistance within manufacturer specified range for the squib/pretensioner (refer to service manual)
- Open-circuit would show very high or infinite resistance (different DTC)
- No supply voltage is applied to the squib except during deployment; do not attempt high-voltage tests
Diagnostic algorithm
- Safety first: Disable the battery per the vehicle service manual and observe the required SRS wait time before touching any airbag connectors or components.
- Retrieve and record all SRS codes and freeze-frame data with a scan tool. Note occurrence counters and history.
- Perform a thorough visual inspection of the wiring harness and connectors for circuit #2: check seat tracks, door hinges, under-seat routing, and any points where the harness bends or is secured.
- Disconnect the connector for the affected squib/pretensioner and check resistance across the squib terminals with a low-ohm meter (service manual procedure). Compare to spec. If resistance is very low, suspect a shorted component.
- With the squib disconnected, check for continuity between the squib circuit conductor and chassis ground. Continuity indicates a short to ground in the harness.
- To isolate the fault, disconnect intermediate connectors or harness sections and re-test resistance/continuity to find where the low resistance disappears. Repair or replace the damaged section.
- If harness and connectors test good and low resistance remains at the squib, replace the airbag/pretensioner (follow manufacturer replacement and disposal procedures).
- If wiring and component are good, suspect internal SRS (SDM) module fault; confirm with manufacturer-level diagnostics before replacing module.
- After repairs, reconnect everything, reconnect the battery, clear codes with a scan tool, and perform required SRS system checks and any post-service self-tests.
- Confirm that the B0086 code does not return and that the SRS lamp functions normally at key-on and self-test.
Likely causes
- Wiring abrasion or insulation damage causing short to chassis ground
- Connector contamination/corrosion or bent pins at the airbag or SDM connector
- Failed squib (inflator) or seatbelt pretensioner with internal short
- Harness routed over sharp edge or pinched at hinge/seat/door area
- Incorrect part installation or accidental bridging of pins during previous service
Fault status
Status
Supplemental Deployment Loop #2 Resistance Low — SRS control module detects abnormally low resistance in deployment circuit #2; inspect wiring, connectors, squib/pretensioner and associated module connections. Risk: affected restraint may not deploy.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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