Honda BF135A - Knock Sensor Troubleshooting

BF135A•BF150A
5-83
3. VTEC signal line open circuit check
-1. Check for the continuity between the spool solenoid
valve harness side connector terminal and A-20 termi-
nal of the test harness.
Is there the continuity?
YES – Perform "4. Symptom reproduction test".
NO – Repair open in the wire between the ECM
and the spool solenoid valve.
4. Symptom reproduction test
-1. Disconnect the test harness and connect each con-
nector securely.
-2. Reset the ECM.
-3. Start the engine and let it warm up by running the
engine at 3,000 min
-1
(rpm) for 5 minutes under no
load.
-4. Disconnect the neutral switch 2P connector.
-5. Increase the engine speed gradually until it reaches
4,500 min
-1
(rpm), and run the engine for a few sec-
onds.
-6. If there is any abnormality, substitute a known-good
ECM and recheck.
• KNOCK Sensor Troubleshooting
MIL blinks 23 times
1. Symptom reproduction test
-1. Reset the ECM.
-2. Turn the ignition switch OFF and connect the test har-
ness.
• Hold the sensor connector connected.
-3. Start the engine and let it warm up by running the
engine at 5,000 min
-1
(rpm) or more for 5 minutes or
more under no load.
-4. Check the MIL.
Does the MIL come ON?
YES – Perform "2. Knock sensor signal line open cir-
cuit check".
NO – Temporary failure (Disappeared)
2. Knock sensor signal line open circuit check
-1. Turn the ignition switch OFF and disconnect the knock
sensor 1P connector.
-2. Check for the continuity between the knock sensor har-
ness side connector (Red/Blue) terminal and the test
harness A-15 terminal.
Is there the continuity?
YES – Perform "3. Knock sensor signal line short cir-
cuit check".
NO – Repair open in the wire between knock sen-
sor and the ECM.
SPOOL SOLENOID VALVE
SIDE CONNECTOR
A-20
A-15