What this code means
B1042 may mean the body control module is seeing a mismatch between the backup wiper signal and the front wiper data it expects.
What the vehicle may do
- The wipers may operate abnormally.
- The vehicle may store the code even if the symptom is intermittent.
Possible fault areas
- Possible BACK_UP(WIPER) circuit issue.
- Possible connector or wiring issue between the windshield wiper control unit and motor and the body control module.
- Possible windshield wiper control unit and motor issue.
Diagnostic path
Code overview
On this Accord Hybrid, B1042 is a front wiper security line error. In plain terms, the body control module may be seeing a mismatch between the backup wiper signal from the windshield wiper control unit and motor, and the front wiper data it expects to see over the network. The vehicle may have wiper operation concerns, or it may simply store the code. The broad areas to think about are the wiper backup signal circuit, the related connectors and wiring, the body control module side of the circuit, and the windshield wiper control unit and motor. Before getting into the pinpoint checks, start with the basic system checks and follow a structured diagnostic approach. If other codes are present, check what they mean first so you are not chasing a symptom caused by a larger network or body electrical issue.
Set up the circuit test
Turn the vehicle to the ON mode. For this B1042 path, the inspection is on the BACK_UP(WIPER) circuit. Disconnect the windshield wiper control unit and motor connector, the 5P connector. Then disconnect body control module connector A, the 66P connector. With both ends of that circuit isolated, perform the inspection in the same order as the test table.
Check for an open in the BACK_UP(WIPER) circuit
With the windshield wiper control unit and motor 5P connector disconnected, and body control module connector A 66P disconnected, check the BACK_UP(WIPER) circuit for an open with IG Mode OFF. A normal open-wire inspection is less than 1 Ω. If that reading is abnormal, the problem is in the circuit, so stay on the wiring and connector side of the diagnosis before moving on.
Check for a short to ground
Next, use the open or shorted wire inspection method for the shorted-circuit check, and apply it to the circuit condition you are testing. Keep the windshield wiper control unit and motor 5P connector disconnected, keep body control module connector A 66P disconnected, and check the BACK_UP(WIPER) circuit for a short to ground with IG Mode OFF. A normal short-to-ground inspection is more than 1 MΩ. If this check is abnormal, the problem is in the circuit.
Call the result and verify
If the circuit checks are normal, this diagnostic path points to a problem with the windshield wiper control unit and motor. Keep verification separate from the circuit testing: after the fault is corrected, verify the repair and confirm B1042 stays gone. The takeaway is simple: for B1042, isolate both ends of the BACK_UP(WIPER) circuit, prove the circuit is not open and not shorted to ground, then use those results to decide whether the fault remains in the circuit or points back to the wiper control unit and motor. For more diagnostic training, visit stepdiagnostics.com.
Final check
This code is often approached by proving the BACK_UP(WIPER) circuit condition first, then using the circuit test results to decide the next diagnostic direction.
For more guided automotive diagnostics, visit STEP Diagnostics.
