BF135A•BF150A
5-56
DTC 143-2: ECT sensor 4 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 4 voltage using the HDS
pocket tester.
Is the measured 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.
Is the measured voltage 4.75 – 5.25V?
YES –
Perform “3. ECT sensor 4 ground line open
circuit check”.
NO –
Repair open in the wire between the ECT
sensor 4 and the ECM.
3. 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.
Is there the continuity?
YES –
Perform “4. ECT sensor 4 check”.
NO –
Repair open in the wire between the ECT
sensor 4 and the engine ground.
4. ECT sensor 4 check
-1. Turn the ignition switch OFF and connect all the con-
nectors.
-2. Turn the ignition switch ON and measure the ECT sen-
sor 4 temperature using the HDS pocket tester.
Does the measurement correspond to the engine
coolant temperature?
YES –
When the DTC appears again, substitute a
known-good ECM and recheck.
NO –
Replace the ECT sensor 4.
ECT SENSOR 4 HARNESS
SIDE 2P CONNECTOR
VIEWED FROM THE
TERMINAL SIDE
TOH3
(RED/GREEN)
ECT SENSOR 4 HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE
TERMINAL SIDE
SG2
(GREEN/RED)