BF135A•BF150A
5-92
6. Heater line open circuit check
-1. Connect the No.3 (Black/White) and the No.4 (White)
terminals of the A/F sensor harness side 4P connector
respectively to the engine ground with the jumper
wires.
-2. Check for the continuity between the test harness C-3
terminal and the engine ground, and between the C-4
terminal and the engine ground.
Is there the continuity?
YES –
Perform "7. Sensor line short circuit check".
NO –
Repair open in the wire between the A/F sen-
sor and the ECM.
7. Sensor line short circuit check
-1. Disconnect the ECM connector B.
-2. Disconnect the A/F sensor 4P connector.
-3. Check for the continuity between the test harness C-3
terminal and the respective terminals of A-4 and A-14
terminals, and between the C-4 terminal and the
respective terminals of A-4 and A-14 terminals.
Is there the continuity?
YES –
Repair short in the wire between the A/F sen-
sor and the ECM.
NO –
Replace the A/F sensor and recheck. If it is
still abnormal, substitute a known-good ECM
and recheck.
• A/F Sensor Troubleshooting
MIL blinks 48 times
1. Symptom reproduction test
-1. Reset the ECM.
-2. Start the engine and let it warm up by running the
engine at 3,000 rpm for 5 minutes or more under no
load. Run the engine at idling for an additional one
minute under no load.
-3. Check the MIL.
Does the MIL come ON?
YES –
Perform "2. A/F sensor line open circuit
check".
NO –
Temporary failure (Disappeared)
2. A/F sensor line open circuit check
-1. Turn the ignition switch OFF. Disconnect the A/F sen-
sor connector and the ECM connector A.
-2. Connect the No.1 (White/Black) terminal of the A/F
sensor harness side 4P connector to the engine
ground to short using a jumper wire.
-3. Check for the continuity between the test harness A-4
terminal and the engine ground.
Is there the continuity?
YES –
Go to the step 4.
NO –
Repair open in the wire between the A/F sen-
sor and the ECM.
-4. Connect the No.2 (Black/Yellow) terminal of the A/F
sensor harness side 4P connector to the engine
ground to short using a jumper wire.
-5. Check for continuity between the test harness A-14 ter-
minal and the engine ground.
Is there the continuity?
YES –
Perform "3. A/F sensor line short circuit
check".
NO –
Repair open in the wire between the A/F sen-
sor and the ECM.
A-4
A-14
A-4
A-14
C-3
C-4
C-4
C-3