Ect Sensor 1 Troubleshooting - Honda BF135A Manual

BF135A•BF150A

• ECT Sensor 1 Troubleshooting

MIL comes ON 6 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 B-8 ter-
minal (+) and the A-2 terminal (–).
A-2
Is the measured voltage 0.22 – 3.15V?
YES – Temporary failure (Disappeared)
NO – Perform "2. ECT sensor 1 signal line open cir-
cuit check".
2. ECT sensor 1 signal line open circuit check
-1. Turn the ignition switch ON. Measure the voltage
between the No. 2 (Red/White) terminal of the ECT
sensor 1 harness side 2P connector and the engine
ground.
ECT SENSOR 1 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE TERMINAL SIDE
Is the measured voltage 4.30 – 5.25V?
YES – Perform "3. ECT sensor 1 line short circuit
check".
NO – Repair open in the wire between the ECM
and ECT sensor 1.
B-8
TE (RED/WHITE)
3. ECT sensor 1 line short circuit check
-1. Turn the ignition switch OFF and disconnect the ECM
connector B.
-2. Check for the continuity between the No. 2 (Red/White)
terminal of the ECT sensor 1 harness side 2P con-
nector and the body ground.
ECT SENSOR 1 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE TERMINAL SIDE
Is there the continuity?
YES – Repair short in the wire between the ECM
and the ECT sensor 1.
NO – Perform "4. ECT sensor 1 ground line short
circuit check".
4. ECT sensor 1 ground line short circuit check
-1. Turn the ignition switch OFF. Check for the continuity
between the No. 1 (Green/Red) terminal of the ECT
sensor 1 harness side 2P connector and the engine
ground.
ECT SENSOR 1 HARNESS SIDE
2P CONNECTOR
SG2 (GREEN/RED)
VIEWED FROM THE TERMINAL SIDE
Is there the continuity?
YES – Perform the 5. ECT sensor 1 check.
NO – Repair open in the wire between the ECM
and the ECT sensor.
TE (RED/WHITE)
5-74