What this code means
B1E77 may indicate an open condition in the right-side BSI radar unit indicator circuit.
What the vehicle may do
- The right-side blind spot alert indicator may not operate normally.
- The blind spot information system may show a warning or limited operation.
Possible fault areas
- Right BSI alert indicator issue
- Possible open or connector concern in the indicator circuit
- Possible ground circuit concern
- Possible right-side BSI radar unit concern
Diagnostic path
Open and code context
On this Accord Hybrid, B1E77 points to an open condition in the right-side BSI radar unit indicator circuit. In plain terms, the radar unit may not be seeing the indicator circuit voltage behave the way it expects when the alert indicator is commanded on or off. The customer may notice the right-side blind spot alert indicator not working normally, or the blind spot system may flag a warning. The broad fault areas can include the right BSI alert indicator, the indicator and ground circuits, connector issues, or the right-side BSI radar unit itself. Since there is no direct bench-style test for the indicator component here, the diagnosis works through the related circuit checks instead of jumping straight to a part.
Start with the basic checks
Before getting into the circuit test, start with the basic system checks and follow a structured diagnostic approach. If other codes are present, treat them as context and make sure they are understood first, but keep this path focused on B1E77.
Confirm the fault is active
For confirmation, turn the vehicle to ON mode and wait for at least 5 seconds. That gives the system time to run the check before you move into the circuit inspection.
Simulate the right alert indicator circuit
Next, prepare for the right BSI alert indicator inspection by disconnecting the right BSI alert indicator 2P connector. Then connect terminals No. 1 and No. 2 of that connector with a jumper wire. Turn the vehicle back to ON mode. If the result is normal, B1E77 changes over to the related indicator-circuit code, and that points to a problem with the right BSI alert indicator. If the result is abnormal, the problem is still in another related part of the circuit path, so keep testing instead of condemning the indicator.
Check the indicator and ground circuits for opens
If the jumper check does not isolate the indicator, move to the BSI_R_IND and ground open-wire inspection. Disconnect the right BSI alert indicator 2P connector and the right-side BSI radar unit 6P connector. Then perform the open-wire checks for the indicator circuit and the ground circuit. The normal result for the BSI_R_IND open-wire inspection is less than 1 Ω, and the normal result for the ground open-wire inspection is also less than 1 Ω. If either check is abnormal, the fault is in the circuit. The exact terminal-to-terminal measurement points need to be identified correctly before measuring, so pause and confirm the connector cavities before probing; do not guess at the terminals.
If the related checks pass
If the other inspection items all show normal results, then the remaining fault area is the right-side BSI radar unit. At that point, the circuit and indicator checks have been used to narrow the diagnosis, instead of assuming the radar unit at the beginning.
Verify the repair
After the fault area is corrected, verify the repair and confirm B1E77 stays gone under the same operating conditions that allowed the code to set. The takeaway is simple: prove the indicator circuit response first, then check the indicator and ground wiring, and only leave the right-side radar unit as the fault area after the related checks pass. For more diagnostic training, visit stepdiagnostics.com.
Final check
B1E77 is best approached as a guided electrical circuit diagnosis: confirm the code behavior, simulate the indicator circuit, check the indicator and ground wiring, and only narrow toward the radarユニt
For more guided automotive diagnostics, visit STEP Diagnostics.
