ENGINE GENERAL INFORMATION AND DIAGNOSIS (M13 ENGINE) 6-2-99
Troubleshooting
Step Action Yes No
1Was “Engine and Emission Control System
Check” performed?
Go to Step 2. Go to “Engine and Emis-
sion Control System
Check” in this section.
2Check HO2S–1 heater power circuit.
1) Disconnect connector from HO2S–1 sen-
sor with ignition switch turned OFF.
2) Check for proper connection to HO2S–1
sensor at “BLK/WHT” and “YEL” wire termi-
nals.
3) If wire and connection are OK, measure
voltage between “BLK/WHT” wire terminal
and engine ground with ignition switch
turned ON.
Is voltage over 10 V?
Go to Step 3. “BLK/WHT” wire open cir-
cuit or shorted to ground
circuit.
3Check HO2S–1 heater power circuit.
1) Disconnect connectors from ECM with igni-
tion switch turned OFF.
2) Measure resistance between “BLK/WHT”
wire terminal of HO2S–1 connector and
“E21-28” terminal wire of ECM connector.
Is resistance below 5
Ω
?
Go to Step 4. “BLK/WHT” wire high
resistance circuit.
4Check HO2S–1 heater drive circuit.
1) Measure resistance between “E23-4” wire
terminal of ECM connector and vehicle
body ground.
Is resistance infinity?
Go to Step 5. “YEL” wire shorted to
ground circuit.
5Check HO2S–1 heater drive circuit.
1) Turn ON ignition switch.
2) Measure voltage between “E23-4” wire ter-
minal of ECM connector and vehicle body
ground.
Is voltage 0 V?
Go to Step 6. “YEL” wire shorted to
power circuit.
6Check HO2S–1 heater drive circuit.
1) Connect connector to HO2S–1 with ignition
switch turned OFF.
2) Turn ON ignition switch.
3) Measure voltage between “E23-4” wire ter-
minal of ECM connector and vehicle body
ground with disconnect connector from
ECM.
Is voltage over 10 V?
Go to Step 7. “YEL” wire open circuit.
7 Check heater of sensor–1.
1) Disconnect HO2S–1 coupler with ignition
switch turned OFF.
2) Check HO2S–1 heater resistance. See Fig.
1.
It is 5.0 – 6.4
Ω
at 20°C (68°F)?
Go to Step 8. Replace HO2S–1.
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