Honda BF135A Manual page 198

Is there the battery voltage?
YES – Go to the step 5.
NO – Blown No. 1 fuse, or repair open in the wire
between the A/F heater relay and the No. 1
fuse.
-5. Turn the ignition switch ON. Measure the voltage
between the No. 3 (White) terminal of the A/F heater
relay harness side 4P connector and the engine
ground.
A/F HEATER RELAY HARNESS
SIDE 4P CONNECTOR
AFHT+ (WHITE)
VIEWED FROM THE
TERMINAL SIDE
Is there the battery voltage?
YES – Go to the step 6.
NO – Repair open in the wire between the A/F
heater relay and the No. 5 fuse.
-6. Check the A/F heater relay (P. 18-20).
Is the A/F heater relay normal?
YES – Go to the step 7.
NO – Replace the A/F heater relay.
-7. Turn the ignition switch OFF and disconnect the ECM
connector A.
-8. Check for the continuity between the No. 4 (Green/
Orange) terminal of the A/F heater relay harness side
4P connector and the No. 25 (Green/Orange) terminal
of the ECM connector A.
A/F HEATER RELAY
HARNESS SIDE
4P CONNECTOR
AFHT-
(GREEN/ORANGE)
Is there the continuity?
YES – Go to the step 9.
NO – Repair open in the wire between the A/F
heater relay and the ECM.
5-45
ECM CONNECTOR A
VIEWED FROM THE
TERMINAL SIDE
-9. Check for the continuity between the No. 3 (White) ter-
minal of the A/F heater relay harness side 4P connec-
tor and the No. 3 (White) terminal of the A/F sensor
harness side 4P connector.
A/F SENSOR HARNESS
SIDE 4P CONNECTOR
AFHT+ (WHITE)
VIEWED FROM THE
TERMINAL SIDE
Is there the continuity?
YES – Perform "3. A/F sensor heater check".
NO – Repair open in the wire between the A/F
heater relay and the A/F sensor.
3. A/F sensor heater check
-1. Turn the ignition switch OFF and disconnect the A/F
sensor 4P connector.
-2. Measure the resistance between the No. 3 (Black) and
the No. 4 (Black) terminals of the A/F sensor side 4P
connector.
A/F SENSOR SIDE 4P
CONNECTOR
AFHT (BLACK)
VIEWED FROM THE
TERMINAL SIDE
Is the resistance 2 – 3
YES – Perform "4. Heater line short circuit check".
NO – Replace the A/F sensor.
BF135A•BF150A
A/F HEATER RELAY
HARNESS SIDE
4P CONNECTOR
AFHT+ (WHITE)
AFHT+ (BLACK)
(at room temperature)?