Ect Sensor 2 Troubleshooting - Honda BF135A Manual

• ECT Sensor 2 Troubleshooting

DTC 140-1: ECT sensor 2 voltage is low
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. Turn the ignition switch ON.
-3. Measure the ECT sensor 2 voltage using the HDS
pocket tester.
Is the measured voltage 0.08 – 4.99V?
YES – Temporary failure (Disappeared)
NO – Perform "2. ECT sensor 2 signal line short cir-
cuit check".
2. ECT sensor 2 signal line short circuit check
-1. Turn the ignition switch OFF. Disconnect the ECT sen-
sor 2 connector and the ECM connector B.
-2. Check for the continuity between the No. 2 (Red/Black)
terminal of the ECT sensor 2 harness side 2P con-
nector and the body ground.
ECT SENSOR 2 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE
TERMINAL SIDE
Is there the continuity?
YES – Repair short in the wire between the ECT
sensor 2 and the ECM.
NO – Perform "3. ECT sensor 2 check".
3. ECT sensor 2 check
-1. Turn the ignition switch OFF and connect the ECT sen-
sor 2 2P connector.
-2. Turn the ignition switch ON and measure the ECT sen-
sor 2 temperature using the HDS pocket tester.
Does the measurement correspond to the engine
coolant temperature?
YES – Substitute a known-good ECM and recheck.
NO – Replace the ECT sensor 2.
5-51
TOH1 (RED/BLACK)
DTC 140-2: ECT sensor 2 voltage is high
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. Turn the ignition switch ON.
-3. Measure the ECT sensor 2 voltage using the HDS
pocket tester.
Is the measured voltage 0.08 – 4.99V?
YES – Temporary failure (Disappeared)
NO – Perform "2. ECT sensor 2 signal line open cir-
cuit check".
2. ECT sensor 2 signal line open circuit check
-1. Turn the ignition switch OFF and disconnect the 2P
connector from the ECT sensor 2.
-2. Turn the ignition switch ON.
-3. Measure the voltage between the No. 2 (Red/Black)
terminal of the ECT sensor 2 harness side 2P con-
nector and the engine ground.
ECT SENSOR 2 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE
TERMINAL SIDE
Is the measured voltage 4.75 – 5.25V?
YES – Perform "3. ECT sensor 2 ground line open
circuit check".
NO – Repair open in the wire between the ECT
sensor 2 and the ECM.
BF135A•BF150A
TOH1 (RED/BLACK)