What this code means
B1658 may indicate a keyless access control unit concern related to the rear exterior antenna circuit.
What the vehicle may do
- The keyless access system may behave inconsistently around the rear of the vehicle.
- Rear trunk or tailgate area antenna functions may not respond as expected.
Possible fault areas
- Rear bumper LF antenna
- EXT TR+ and EXT TR- circuit wiring
- Loose or poor connector contact
- Keyless access control unit
Diagnostic path
Opening context
On this 2010 through 2017 Honda Accord with the 2.4 gas engine, B1658 is a keyless access control unit code. In plain language, the system may be seeing a problem in the rear exterior antenna circuit used by the keyless access system. The customer may notice keyless access behavior that is inconsistent around the rear of the vehicle, and the possible fault areas can include the rear bumper LF antenna, the EXT TR+ and EXT TR- wiring, connector condition, or the keyless access control unit itself. We’re going to keep the diagnosis tight: first prove the code is current, then check whether the control unit can drive the rear bumper antenna circuit, and then check the circuit for an open or high resistance condition.
Confirm whether B1658 is current
Start by clearing the DTCs with the HDS. From the HDS, select MODE MENU, go into SELF CHECK, run the self check, and then check for DTCs again. If B1658 comes right back, continue with the rear bumper antenna circuit test. If B1658 does not return, treat it as an intermittent failure. The system is OK at this time, so concentrate on loose or poor connections rather than guessing at parts.
Check the EXT TR+ and EXT TR- output at the rear bumper antenna connector
Next, check the keyless access control unit output on the EXT TR+ and EXT TR- lines. Press the engine start/stop button to select OFF mode, then disconnect the rear bumper LF antenna 2P connector. Press the engine start/stop button again to select ON mode. On the HDS, select KEYLESS ACCESS CONTROL from the ONE-PUSH START system menu, enter FUNCTIONAL TESTS, and set up the test for TRUNK/TAILGATE/REAR BUMPER ANTENNA. Connect the voltmeter between rear bumper LF antenna 2P connector No. 1, the LT GRN wire, and connector No. 2, the GRY wire. If there is voltage during this test, the diagnostic path calls for replacing the rear bumper LF antenna. If there is no voltage, move on and check the wiring between the antenna connector and the keyless access control unit.
Check for an open or high resistance in the EXT TR lines
For the wiring check, press the engine start/stop button to select OFF mode. Leave the rear bumper LF antenna 2P connector disconnected, and disconnect keyless access control unit connector A, the 32P connector. Now check continuity on both circuits. For EXT TR+, check between keyless access control unit connector A 32P No. 24, LT GRN, and rear bumper LF antenna 2P connector No. 1, LT GRN. For EXT TR-, check between keyless access control unit connector A 32P No. 8, GRY, and rear bumper LF antenna 2P connector No. 2, GRY. If both checks have continuity, the diagnostic path calls for replacing the keyless access control unit. If there is no continuity, repair the open or high resistance in the wire.
Takeaway
The key to B1658 is not to jump straight to a module. Prove the code is current, check whether the rear bumper LF antenna is being driven, then prove the EXT TR+ and EXT TR- wiring before making the final call. For more diagnostic training, visit stepdiagnostics.com.
Final check
B1658 is often approached by confirming the code first, then separating an antenna-side problem from a wiring or control-unit-side problem.
For more guided automotive diagnostics, visit STEP Diagnostics.
