Keyless Access System Symptom Troubleshooting Index (2025)

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2025 Honda Odyssey, 2024 Honda Odyssey, 2023 Honda Odyssey, 2022 Honda Odyssey, and 2021 Honda Odyssey. However, it is still accessible from the selected car via links, so may be relevant.

Symptom	Diagnostic procedure	Also check for
Cannot select ON mode with keyless access and with the keyless remote touching the engine start/stop switch	Poor connections at the body control module Keyless remote Body control module Engine start/stop switch Harness/connections
Cannot select ON mode with keyless access, but can select ON mode with the keyless remote touching the engine start/stop switch	Body control module LF antenna Keyless remote Low or weak keyless remote battery Harness/connections
Cannot select ON mode with the keyless remote touching the engine start/stop switch, but can select ON mode with keyless access	Check the body control module	Body control module is not registered Body control module IGN TRX line open/short Harness/connections
The mode changes between ACCESSORY and ON, but it does not change to OFF	Check the body control module Check the TCM	Body control module ATP-P line open TCM
The mode changes between ACCESSORY and ON, but it is difficult to change to OFF	Check the body control module Check the gauge control module Check the TCM	Gauge control module Body control module PCM B-CAN communication line open/short F-CAN communication line open/short Speed signal line open TCM
Engine start/stop switch does not work	Check for DTCs. If any DTC is indicated, go to the DTC troubleshooting	ACC relay circuit Body control module Engine start/stop switch SS1(+) line short SS2(-) line short Harness/connections
Engine does not crank (power supply is normal)	Check the brake pedal position switch Check the body control module	Body control module STS line open/short Brake pedal position switch STOP SW line open/short
The engine starts, but stalls immediately	No power to PCM No power to body control module Body control module Gauge control module Harness/connections

Symptom	Diagnostic procedure	Also check for
Immobilizer/security indicator blinks	Gauge control module Body control module PCM Harness/connections
All the doors will not lock and unlock	Body control module LF antenna Driver's door lock knob switch Door outer handle touch sensor/lock switch Door lock actuators Keyless remote Low or weak keyless remote battery Not registered
The doors will not unlock or lock with the keyless remote, but will unlock or lock with the door outer handles	Keyless remote battery dead Keyless remote Body control module Harness/connections B-CAN communication line
The doors will not unlock or lock with the door outer handle touch sensor or lock switch, but will unlock or lock with the keyless remote	Door outer handle touch sensor/lock switch Body control module Keyless remote Not registered Harness/connections