What this code means
B1129 may indicate that the driver's door lock knob switch signal is not being interpreted correctly by the power window master switch.
What the vehicle may do
- The driver's door lock operation may act oddly.
- The lock knob switch status may not report cleanly.
- The code may set while operating the driver's door lock knob switch.
Possible fault areas
- Possible driver's door lock knob switch signal circuit issue.
- Possible connector or harness issue in the driver's door wiring path.
- Possible driver's door latch connector or power window master switch connector concern.
- Possible power window master switch fault after the circuit checks pass.
Diagnostic path
Opening and code logic
On this 2020 to 2025 Honda CR-V hybrid, B1129 points to a possible driver's door lock knob switch malfunction. In plain language, the power window master switch may be seeing the lock and unlock signals as active at the same time. The vehicle may have odd driver's door lock behavior, the lock knob switch may not report cleanly, or the code may set during switch operation. The broad fault areas can include the driver's door lock knob switch signal circuits, connector or harness issues between the driver's door latch and the power window master switch, or the power window master switch itself. Start with the basic system checks first. If other codes are present, check what they mean first and follow a structured B-CAN diagnostic approach before focusing on this one code.
Confirm the symptom
To confirm the fault path for B1129, operate the driver's door lock knob switch ON and OFF several times. The key point is the setting logic: if the power window master switch detects the driver's door lock knob switch and the unlock switch ON at the same time, it treats that as an abnormal signal condition and stores B1129.
Choose the inspection path
For this code, the inspection item is the driver's door lock knob switch test. The wiring checks are focused on the DR_SILCON_LOCK and DR_SILCON_UNLOCK circuits. Before checking for shorts, disconnect the power window master switch connector, the 37P connector, and disconnect the driver's door latch connector, the 10P connector.
Shorted wire checks
With those connectors disconnected, perform the DR_SILCON_LOCK and DR_SILCON_UNLOCK shorted wire inspection. Keep IG Mode OFF for these checks. First, check DR_SILCON_LOCK to DR_SILCON_UNLOCK for a wire-to-wire short. Normal is more than 1 MΩ. Then check DR_SILCON_LOCK shorted to ground. Normal is more than 1 MΩ. Then check DR_SILCON_UNLOCK shorted to ground. Normal is more than 1 MΩ. If any of those checks are abnormal, the problem is in the circuit.
Do not guess on connector details
One caution on this diagnostic: the exact terminal identification and the detailed open-or-shorted circuit test method have to be correct before probing. If that connector information or test method is not available at the vehicle, pause and get the right connector and circuit details before continuing. Do not back-probe or jump terminals by guesswork.
Power window master switch decision
If the other inspection items show a normal condition, the remaining fault area is the power window master switch. At that point, the diagnostic decision is that there is a problem with the power window master switch.
Verification and takeaway
Keep verification separate from the circuit testing. After the diagnostic path is completed and any correction is made, repeat the same driver's door lock knob switch ON and OFF operation several times and confirm B1129 does not come back. The takeaway is simple: B1129 is a signal conflict code, so prove the lock and unlock signal circuits are not shorted together or to ground before condemning the master switch. For more diagnostic training, visit stepdiagnostics.com.
Final check
B1129 is often approached as a lock and unlock signal conflict: check the circuits first, then consider the power window master switch only after the other inspection items are normal.
For more guided automotive diagnostics, visit STEP Diagnostics.
