5-72 FI SYSTEM
Step 2 (When indicating C44/P0135:)
1) Connect the HO2 sensor coupler.
2) Insert the needle pointed probes to the HO2 sensor coupler.
3) Turn the ignition switch ON and measure the heater voltage
between W/B wire A and ground.
4) If the tester voltage indicates the battery voltage, it is good
condition.
Heater voltage: Battery voltage
NOTE:
Battery voltage can be detected only before starting the engine.
09900-25008: Multi-circuit tester set
09900-25009: Needle pointed probe set
Tester knob indication: Voltage ()
Is the voltage OK?
• O/W or W/B wire open or shorted to ground, or
poor Z connection
• Recheck each terminal and wire harness for
open circuit and poor connection.
YES
• If wire and connection are OK, intermittent trou-
ble or faulty ECM.
• Replace the ECM with a known good one, and
inspect it again.
• Open or short circuit in the W/B wire or O/W
wire
NO
• Loose or poor contacts on the ECM coupler
(terminal Z) or HO2 sensor coupler
5) After repairing the trouble, clear the DTC using SDS tool.
(5-25)
(+ W/B A – - Ground)
2
2
ECM coupler (Harness side)
V