Honda BF135A - Iat Sensor Troubleshooting

BF135A•BF150A
5-78
6. CMP sensor check
-1. Reset the ECM.
-2. Start the engine and let it run at idling under no load.
Check the MIL.
Does the MIL come ON?
YES – Replace the CMP sensor and recheck. If the
MIL comes ON again, substitute a known-
good ECM and recheck.
NO – End of the check
• IAT Sensor Troubleshooting
MIL blinks 10 times.
1. Symptom reproduction check
-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 B-11 terminal (+)
and the A-2 terminal (-) of the test harness.
Is the voltage 0.08 – 4.92V?
YES – Temporary failure (Disappeared)
NO – Perform "2. IAT sensor signal line open circuit
check".
2. IAT sensor signal line open circuit check
-1. Turn the ignition switch OFF and disconnect the IAT
sensor 2P connector.
-2. Turn the ignition switch ON. Measure the voltage
between the No. 2 (Red/Yellow) terminal of the IAT
sensor harness side 2P connector and the engine
ground.
Is the voltage 4.75 – 5.25V?
YES – Perform “3. IAT sensor signal line short circuit
check”.
NO – Repair open in the wire between the IAT sen-
sor and the ECM.
A-2
B-11
IAT SENSOR HARNESS SIDE
2P CONNECTOR
VIEWED FROM THE TERMINAL SIDE
TA (RED/YELLOW)