Honda BF135A - Knock Sensor Troubleshooting

BF135A•BF150A
5-43
3. VTEC signal line short circuit check
-1. Disconnect the ECM connector A.
-2. Check for the continuity between the No. 20
(Green/Yellow) terminal of the ECM connector A and
the body ground.
Is there the continuity?
YES – Repair short in the wire between the ECM
and the spool solenoid valve.
NO – Perform “4. VTEC signal line open circuit
check”.
4. VTEC signal line open circuit check
-1. Check for the continuity between the spool solenoid
valve harness side connector terminal and the No. 20
(Green/Yellow) terminal of the ECM connector A.
Is there the continuity?
YES – Substitute a known-good ECM and recheck.
NO – Repair open in the wire between the ECM
and the spool solenoid valve.
• Knock Sensor Troubleshooting
DTC 23-1: Knock sensor detects failure
1. Symptom reproduction test
-1. Connect the HDS pocket tester and clear the DTC
once. If the DTC can not be cleared, go on the trou-
bleshooting.
-2. Start the engine and warm it up for 5 minutes or more
by running the engine at 5,000 min
-1
(rpm) or more
under no load.
-3. Check the DTC again with the HDS pocket tester.
Does the DTC 23-1 appear?
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. Disconnect the knock
sensor connector and the ECM connector A.
-2. Check for the continuity between the (Red/Blue) termi-
nal of the knock sensor harness side connector and
the No. 15 (Red/Blue) terminal of the ECM connector
A.
Is there the continuity?
YES – Perform “3. Knock sensor signal line short cir-
cuit check”.
NO – Repair open in the wire between the knock
sensor and the ECM.
ECM CONNECTOR A
VIEWED FROM THE
TERMINAL SIDE
VTS (GREEN/YELLOW)
SPOOL SOLENOID
VALVE HARNESS
SIDE CONNECTOR
ECM CONNECTOR A
VTS (GREEN/YELLOW)
VIEWED FROM THE
TERMINAL SIDE
KNOCK SENSOR
HARNESS SIDE 1P
CONNECTOR
ECM CONNECTOR A
KS
(RED/BLUE)
VIEWED FROM THE
TERMINAL SIDE