B1792 – Front passenger seat belt pretensioner 2 not connected (BYD)

B1792 means the front passenger seat belt pretensioner circuit has an “unconnected” condition on your BYD. In plain terms, the SRS system cannot “see” one of the passenger-side belt pretensioner stages, so crash protection may not work as designed. You will usually get an airbag/SRS warning and a stored fault that will not clear until the wiring issue gets fixed. According to BYD factory diagnostic data, this manufacturer-specific code indicates: Front passenger seat belt pretensioner 2 not connected. Because BYD controls the exact logic, confirm the fault in the SRS module with a scan tool that fully supports BYD SRS functions.

B1792 Quick Answer

On a BYD Dolphin (2020), B1792 points to an open or disconnected circuit for the front passenger seat belt pretensioner 2. Diagnose the connector, harness, and seat-side components using OEM SRS-safe test methods before replacing parts.

What Does B1792 Mean?

Official meaning (BYD-defined): “Front passenger seat belt pretensioner 2 not connected.” In practice, the SRS system flags the passenger belt pretensioner as unavailable or unreliable, and it turns the SRS warning on. This matters because pretensioners tighten the belt in a crash, and the system needs confirmed connectivity to arm them.

What the module checks and why it sets the code: The SRS control unit monitors the pretensioner 2 circuit for continuity and a valid electrical signature. When it reads a value that matches an open circuit, unplugged connector, or excessive resistance, it logs B1792. That “not connected” decision guides your diagnosis toward wiring, connectors, and seat-area damage first, not immediate pretensioner replacement.

Theory of Operation

Under normal conditions, the BYD SRS control unit continuously supervises each belt pretensioner stage. It does this with a low-energy monitoring method that verifies the circuit remains intact. The module expects a stable, plausible signature at all times while the vehicle runs.

For B1792, the supervision result matches a disconnected state on the front passenger pretensioner 2 circuit. A loose under-seat connector, a partially backed-out terminal, or harness strain from seat movement can break that signature. Once the SRS module sees the fault for long enough, it stores the code and commands the warning indicator.

Symptoms

These are the most common signs you will notice with this BYD SRS connectivity fault.

• SRS warning Airbag/seat belt warning lamp stays on
• Message Cluster warning about SRS or restraint system (wording varies by BYD)
• Stored DTC B1792 present in SRS module memory and returns after key cycles
• Failed readiness SRS self-check does not complete normally
• Scan data Passenger pretensioner 2 status shows “fault,” “open,” or “not connected” (tool-dependent)
• Intermittent fault Warning flickers after moving the passenger seat or hitting bumps
• Other SRS codes Companion seat/buckle/occupant-related codes may appear if the harness gets disturbed

Common Causes

• Partially unseated pretensioner connector: A connector that looks latched can still leave the squib pins open, so the SRS module flags the circuit as not connected.
• Harness damage under the passenger seat: Seat track movement can pinch or stretch the pretensioner 2 wiring and create an open circuit.
• Terminal spread or poor pin fit: Loss of terminal tension raises contact resistance until the module interprets the pretensioner circuit as disconnected.
• Corrosion or moisture in the seat-area connector: Moisture film or corrosion products interrupt the low-energy SRS circuit and cause an open-circuit style fault.
• Incorrect prior seat removal or interior work: Work around the BYD Dolphin passenger seat can leave the pretensioner 2 branch disconnected or routed incorrectly.
• Aftermarket seat cover or accessory interference: Added accessories can tug on the harness, strain the connector, or prevent full engagement of the lock.
• Open circuit in the pretensioner 2 wiring (either leg): A break in either conductor between the SRS module and pretensioner assembly prevents the module from seeing a valid load.
• Short to ground or short to power on the pretensioner circuit: A short can force the module to shut down that output and report the device as not connected.
• Incorrect or incompatible pretensioner/seat belt assembly installed: A mismatched BYD component can present the wrong electrical signature and the module will treat it as disconnected.

Diagnosis Steps

You need a scan tool with full BYD SRS access, including SRS DTC subtypes and data. Use OEM-approved SRS depowering procedures before touching any seat belt or airbag connector. Avoid standard test lights and piercing probes on SRS wiring. Use a DVOM for power and ground voltage-drop checks at approved points, and follow BYD-approved methods for any pretensioner circuit load testing.

1. Confirm B1792 in the SRS/Restraint module and record all stored and pending DTCs. Save freeze frame data if available, especially battery voltage, ignition state, vehicle speed, and any event counters. Freeze frame shows the conditions when the module set the fault. Use a scan tool snapshot later to capture an intermittent while you move the seat or harness.
2. Perform a quick visual inspection before any meter work. Check the passenger seat area for loose connectors, harness strain at the seat track, and signs of prior seat removal. Inspect the fuse and power distribution that feeds the SRS system and related body power supplies. A low system voltage event can create misleading SRS connectivity faults.
3. Verify SRS module power and ground integrity with voltage-drop testing under load. Command an approved SRS self-test with the scan tool if supported, then measure ground drop during module activity. Keep ground drop under 0.1 V with the circuit operating. Do not rely on continuity checks alone for SRS grounds.
4. Depower the SRS system using OEM procedures and wait the specified time before disconnecting any SRS connectors. Confirm the system stays powered down. Treat the seat belt pretensioner circuit as live until you complete the depower process. Do not skip this step for “just a quick look.”
5. Inspect the front passenger seat belt pretensioner 2 connector(s) and any in-line connectors in that branch. Look for a broken CPA/lock, bent pins, terminal push-out, corrosion, or evidence of overheating. Verify the connector fully seats and the lock engages. Correct routing matters, so confirm the harness does not pull tight at full seat travel.
6. Check harness integrity from the pretensioner connector back toward the body harness. Focus on common stress points under the seat and near the seat track. Look for crushed conduit, rubbed insulation, or spots where the harness can snag. If you find damage, repair the wiring using OEM-approved methods for SRS circuits.
7. Use only OEM-approved test methods to evaluate the pretensioner 2 circuit. Many BYD platforms use SRS-specific shorting bars and monitoring logic, so generic resistance probing can damage components or give false readings. If BYD service information allows, test for opens and shorts in the two circuit legs using an approved break-out or test adapter. Verify neither leg shorts to ground or power.
8. With the system reassembled and safe, run the scan tool’s SRS data checks. Look for any parameter that indicates “pretensioner not connected” or “circuit open” for the front passenger pretensioner 2. If the tool supports it, perform a wiggle test while monitoring status. Use a snapshot to capture the exact moment the status flips during seat movement.
9. If B1792 returns immediately on key-on after proper connector seating, isolate the fault by section. Confirm the issue follows the seat/harness movement or stays fixed with the seat stationary. A fault that changes with motion points to a connector or harness issue under the seat. A fixed hard fault points to a persistent open, short, or incorrect component.
10. After you correct the verified root cause, clear SRS DTCs with the proper scan tool and rerun the SRS self-check. Confirm the code does not reset and the SRS warning lamp operates normally. Recheck seat travel end-to-end to ensure the harness stays protected and the fault does not return.

Professional tip: On seat-mounted SRS circuits, intermittent “not connected” faults often come from terminal fit, not the pretensioner itself. Do not condemn the pretensioner until you prove connector lock engagement and pin tension. Always verify power and ground health first, because low voltage can trigger false SRS connectivity decisions. Use freeze frame to see if the fault set during cranking or a low battery event.

Possible Fixes

• Reseat and lock the pretensioner 2 connector: Fully engage the connector and CPA/secondary lock, then confirm the harness has strain relief through full seat travel.
• Repair damaged wiring under the passenger seat: Correct opens, shorts, or chafed insulation using OEM-approved SRS wiring practices and routing protection.
• Clean and correct terminal fit issues: Address corrosion, terminal push-out, or pin spread, and restore proper terminal retention and contact pressure.
• Correct an installation or compatibility error: Verify the BYD Dolphin uses the correct front passenger belt/pretensioner configuration and correct any mismatched components.
• Secure the harness to prevent repeat failures: Re-clip, re-route, and protect the harness so seat movement cannot pull on the connector or wiring.
• Clear DTCs and confirm the repair with an SRS self-check: Use a scan tool with full BYD SRS access and confirm B1792 stays cleared after multiple key cycles.

Can I Still Drive With B1792?

You can usually drive a 2020 BYD Dolphin with B1792, but you should treat it as a safety-critical fault. This BYD manufacturer-specific code means the SRS control unit believes the front passenger seat belt pretensioner 2 circuit is not connected. That condition can disable that pretensioner and may affect how the SRS system manages a crash event. Drive only as needed to reach a qualified repair facility. Do not transport a front passenger until you confirm proper operation. Do not unplug or move under-seat connectors while the SRS stays powered. Follow BYD depowering procedures before any inspection.

How Serious Is This Code?

This code is serious because it involves the occupant restraint system. Unlike comfort or body codes, an SRS “not connected” status indicates the system may not protect the front passenger as designed. Sometimes the root cause is simple, like a partially seated connector under the seat. Other times, the harness or pretensioner has damage. Treat the entire SRS function as potentially compromised until testing proves otherwise. Diagnosis requires an SRS-capable scan tool that can read BYD SRS data and run guided checks. Use only OEM-approved test methods. Avoid probing squib or pretensioner circuits with standard meters and leads.

Common Misdiagnoses

Technicians often replace the pretensioner or seat belt assembly immediately because the code says “not connected.” That wastes money when the real fault is a loose CPA lock, corrosion, a pin pushed back in the connector, or harness strain from seat travel. Another common mistake involves checking continuity with a standard ohmmeter across a pretensioner circuit. That test can violate OEM handling rules and can damage SRS components. Some shops also clear the code to “see if it comes back,” which erases freeze-frame and status data that helps pinpoint an intermittent disconnect. Confirm connector fit, terminal tension, and harness integrity first, with SRS-safe procedures.

Most Likely Fix

The most frequent confirmed repair direction is restoring a reliable connection at the front passenger seat belt pretensioner 2 connector and its mating harness. That includes reseating the connector, correcting terminal damage, and securing the harness so seat movement cannot pull it. A second common direction involves repairing an open in the pretensioner circuit wiring between the SRS module and the pretensioner connector, then verifying the SRS module sees the circuit as connected in live data. Do not condemn the pretensioner until you prove power, ground, and circuit integrity per BYD service information.

Repair Costs

SRS/airbag repair costs vary significantly by component. Diagnosis must be performed by a qualified technician with SRS-capable equipment. Do not attempt airbag system repairs without proper training and safety procedures.

Last updated: March 29, 2026