Ect Sensor 4 Troubleshooting - Honda BF135A Manual

• ECT Sensor 4 Troubleshooting

MIL blinks 27 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. Turn the ignition switch ON.
-4. Measure the voltage between the test harness A-6 ter-
minal (+) and the A-2 terminal (–).
A-2
Is the voltage 0.08 – 4.99V?
YES – Temporary failure (Disappeared)
NO – Perform "2. ECT sensor 4 signal line open cir-
cuit check".
2. ECT sensor 4 signal line open circuit check
-1. Turn the ignition switch OFF and disconnect the 2P
connector from the ECT sensor 4.
-2. Turn the ignition switch ON.
-3. Measure the voltage between the No.2 (Red/Green)
terminal of the ECT sensor 4 harness side 2P con-
nector and the engine ground.
ECT SENSOR 4 HARNESS
SIDE 2P CONNECTOR
VIEWED FROM THE TERMINAL SIDE
Is the voltage 4.75 – 5.25V?
YES – Perform "3. ECT sensor 4 signal line short cir-
cuit check".
NO – Repair open in the wire between the ECT
sensor 4 and the ECM.
5-89
A-6
TOH3 (RED/GREEN)
3. ECT sensor 4 signal line short circuit check
-1. Turn the ignition switch OFF. Disconnect the ECT sen-
sor 4 connector and the ECM connector B.
-2. Check for the continuity between the No.2 (Red/
Green) terminal of the ECT sensor 4 harness side 2P
connector and the body ground.
ECT SENSOR 4 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE TERMINAL SIDE
Is there the continuity?
YES – Repair short in the wire between the ECT
sensor 4 and the engine ground.
NO – Perform "4. ECT sensor 4 ground line open
circuit check".
4. ECT sensor 4 ground line open circuit check
-1. Connect the ECM connector B.
-2. Check for the continuity between the No.1 (Green/
Red) terminal of the ECT sensor 4 harness side 2P
connector and the body ground.
ECT SENSOR 4 HARNESS SIDE
2P CONNECTOR
SG2 (GREEN/RED)
VIEWED FROM THE TERMINAL SIDE
Is there the continuity?
YES – Perform "5. ECT sensor 4 check".
NO – Repair open in the wire between the ECT
sensor 4 and the engine ground.
BF135A•BF150A
TOH3 (RED/GREEN)