FI SYSTEM 4-43
“C29” STP SENSOR CIRCUIT MALFUNCTION
DETECTED CONDITION POSSIBLE CAUSE
Signal voltage low or high. • STP sensor maladjusted.
Difference between actual throttle opening and • STP sensor circuit open or short.
opening calculated by ECM in larger than specified • STP sensor malfunction.
value. • ECM malfunction.
0.20 V
Sensor Voltage < 4.80 V
(
without the above range.
)
INSPECTION
• Remove the the fuel tank. ( 4-48)
Turn the ignition switch OFF.
Check the STP sensor coupler for loose or poor contacts.
If OK, then measure the STP sensor input voltage.
Disconnect the STP sensor coupler (White color).
Turn the ignition switch ON.
Measure the voltage at the Red wire and ground.
If OK, then measure the voltage at the Red wire and B/Br wire.
STP sensor input voltage: 4.5 – 5.5 V
(
+Red – -Ground
)
+Red – -B/Br
\ 09900-25008: Multi circuit tester
W Tester knob indication: Voltage (
)
No
Loose or poor contacts on
the ECM coupler.
Open or short circuit in the
Red wire or B/Br wire.
Ye s
Turn the ignition switch OFF.
Remove the air cleaner element. (2-4)
Disconnect the STP sensor coupler (White color).
Check the continuity between Yellow wire and ground.
STP sensor continuity:
∞Ω∞Ω
∞Ω∞Ω
∞Ω (Infinity)
(Yellow wire – Ground)
If OK, then measure the STP sensor resistance at the cou-
pler (between Yellow and Black wires).
Close and open the secondary throttle valve by finger
through the air cleaner box, and measure the valve clos-
ing and opening resistance.
STP sensor resistance
Secondary throttle valve is closed: Approx. 0.8 k
ΩΩ
ΩΩ
Ω
Secondary throttle valve is opened: Approx. 3.9 k
ΩΩ
ΩΩ
Ω
\ 09900-25008: Multi circuit tester
V Tester knob indication: Resistance (
ΩΩ
ΩΩ
Ω)
No
Reset the STP sensor
position correctly.
(4-62)
Replace the STP sensor
with a new one.
1
2
1
1
V
Red
Ground
2
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