Code
B0073
HUMMER
B — Body
Supplemental Deployment Loop #1 Resistance Low
AI status
Completed
Completed
100%
Causes
- Shorted squib/pretensioner wiring (short to ground or battery).
- Damaged or corroded connector at airbag or pretensioner.
- Faulty airbag squib or pretensioner with internal short.
- Moisture intrusion in connector or wiring harness.
- Incorrect replacement component or incorrect resistor installed during prior repairs.
- Faulty Sensing and Diagnostic Module (SDM)/airbag control module.
Symptoms
- Airbag/SRS warning lamp illuminated on dash.
- Possible disablement of one or more airbags or pretensioners.
- Vehicle stores B0073 in airbag/SDM memory (may be accompanied by other SRS codes).
- No deployment when commanded (system precaution).
What to check
- Read SRS/SDM codes and freeze frame data with a capable scan tool.
- Confirm battery voltage is stable before and during diagnosis.
- Visual inspection of connectors, wiring, and components for damage, corrosion, or repair evidence.
- Check harness routing under seats, in door sills, behind trim where loop #1 runs.
- Measure resistance at squib/pretensioner connector and at module harness (with power removed).
- Check for continuity to ground (short) from the deployment circuit conductors.
Signal parameters
- Expected: Manufacturer-specified low-ohm squib resistance (device-specific; typically a small resistance value — often in the low ohm range).
- Fault condition: Measured resistance well below the manufacturer lower limit or near 0 Ω (indicating a short).
- Open-circuit condition: Very high or infinite resistance (different DTC).
- Voltage checks: With system powered, shorted circuit may pull voltage low on the deployment driver; measure only with proper procedures and tools.
Diagnostic algorithm
- Safety first: Disable SRS power per manufacturer procedure (disconnect battery and wait the specified time for capacitors to discharge) before inspecting or disconnecting any airbag components.
- Retrieve and record all SRS codes and freeze-frame data with a compatible scanner. Note any other related codes.
- Perform a careful visual inspection of connectors, wiring, and components associated with loop #1 (under seats, in doors, seat belt pretensioner area, steering column/clock spring if applicable). Look for chafing, pinching, corrosion, or signs of previous repair.
- With battery disconnected and following safety rules, disconnect the squib/pretensioner connector(s) for loop #1 and measure resistance across the squib pins. Compare to manufacturer spec. A value significantly below the specified minimum or near 0 Ω indicates an internal short in the device or shorted wiring.
- Measure resistance from the squib pin to chassis ground and to battery positive to check for short-to-ground or short-to-voltage paths. If low resistance to ground is found, trace and repair wiring insulation faults or connector damage.
- If squib/pretensioner measures correct while disconnected, measure resistance from the SDM connector end of the harness to the squib connector to isolate whether the short is in the harness or the device. Perform a wiggle test while monitoring resistance to find intermittent shorts.
- Inspect and test related components such as the clock spring (if steering wheel squib is involved) and seatbelt pretensioner functionality.
- If wiring and components test OK, consider SDM/module driver fault. Follow manufacturer procedures for SDM bench testing or replacement; some SDM faults require dealer-level tools and programming.
- After repairs, clear codes, reconnect battery, and perform SRS system self-test with scan tool. Verify code does not return and perform road/seat checks as required by service manual.
Likely causes
- Damaged wiring under seat or in door/side-panel harness where loop #1 circuits run.
- Corroded or bridged pins in the squib/pretensioner connector.
- Shorted airbag squib (deployed or internally damaged).
- Clock spring (if loop includes steering wheel squib) failure causing low resistance path.
- Prior crash repair left improper wiring or aftermarket parts.
Fault status
Status
Supplemental Deployment Loop #1 Resistance Low — The SRS control module has detected abnormally low resistance in deployment circuit #1 (possible short). Airbag/pretensioner function may be impaired.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Repair manuals
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138
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