Honda BF135A - Ect Sensor 3 Troubleshooting

BF135A•BF150A
5-52
3. ECT sensor 2 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 2 harness side 2P
connector and the body ground.
Is there the continuity?
YES – Perform “4. ECT sensor 2 check”.
NO – Repair open in the wire between the ECT
sensor 2 and the engine ground.
4. ECT sensor 2 check
-1. Turn the ignition switch OFF and connect all the con-
nectors.
-2. Turn the ignition switch ON. Measure the ECT sensor
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.
• ECT Sensor 3 Troubleshooting
DTC 141-1: ECT sensor 3 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 3 voltage using the HDS
pocket tester.
Is the measured voltage 0.08 – 4.99V?
YES – Temporary failure (Disappeared)
NO – Perform “2. ECT sensor 3 signal line short cir-
cuit check”.
2. ECT sensor 3 signal line short circuit check
-1. Turn the ignition switch OFF. Disconnect the ECT sen-
sor 3 connector and the ECM connector B.
-2. Check for the continuity between the No. 2 terminal
(Red) of the ECT sensor 3 harness side 2P connector
and the body ground.
Is there the continuity?
YES – Repair short in the wire between the ECT
sensor 3 and the ECM.
NO – Perform “3. ECT sensor 3 check”.
3. ECT sensor 3 check
-1. Turn the ignition switch OFF and connect the ECT sen-
sor 3 2P connector.
-2. Turn the ignition switch ON and measure the ECT sen-
sor 3 temperature using the HDS pocket tester.
Does the measurement agree with the engine
coolant temperature?
YES – Substitute a known-good ECM and recheck.
NO – Replace the ECT sensor 3.
ECT SENSOR 2 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE
TERMINAL SIDE
SG2
(GREEN/RED)
ECT SENSOR 3 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE
TERMINAL SIDE
TOH2 (RED)