Buell 2002 S3T Service Manual page 272

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TROUBLE CODE 15
GENERAL
Intake Air Temperature Sensor
The ECM supplies and monitors a signal at Pin 10 of [11] to
one side of the intake air temperature sensor (IAT sensor).
The other side of the IAT sensor is connected to a common
sensor ground, which is also connected to the ECM (Pin 7 of
[11]).
See Table 4-18. The IAT sensor is a thermistor device, mean-
ing that at a specific temperature, it will have a specific resis-
tance across its terminals. As this resistance varies, so does
the supplied voltage (Pin 10).
●
At high temperatures, the resistance of the sensor is
very low. This effectively lowers the signal voltage on Pin
10.
●
At low temperatures, the resistance is very high, allowing
the voltage to rise close to the supplied voltage of 5 volts.
The ECM monitors this voltage to compensate for various
operating conditions.
DIAGNOSTICS
Diagnostic Tips
The Scanalyzer displays intake air temperature in degrees.
An intermittent may be caused by a poor connection, rubbed
through wire insulation or a wire broken inside the insulation.
Check for the following conditions:
●
Poor connection. Inspect ECM harness connector for
backed out terminals, improper mating, broken locks
improperly formed or damaged terminals, poor terminal-
to-wire connection and damaged harness.
●
Perform 4.8 WIGGLE TEST
connections and harness check out OK, use the Scana-
lyzer to check intake air temperature reading while mov-
ing related connectors and wiring harness. If the failure
is induced, the IAT sensor display will change.
●
Shifted sensor. The temperature-to-resistance values
table may be used to test the ET sensor at various tem-
perature levels in order to evaluate the possibility of a
shifted (out-of-calibration) sensor which may result in
driveability problems.
to locate intermittents. If
Diagnostic Notes
The reference numbers below correlate with the circled num-
bers on the Code 15 flow charts.
1. Connect BREAKOUT BOX (Part No. HD-42682) to EFI
harness only (leave ECM disconnected). See
KOUT BOX.
2. Use HARNESS CONNECTOR TEST KIT (Part No. HD-
41404), gray socket probes and patch cord.
3. Use HARNESS CONNECTOR TEST KIT, gray pin probe
and patch cord.
Scanalyzer Notes
The Scanalyzer icon appears at those points in the flow chart
where the Scanalyzer can be used.
Table 4-18. Intake Air Temperature
Sensor Specifications
VOLTS RESISTANCE
0.49 1086
0.68 1561
0.86 2077
1.13 2920
1.40 3889
2.25 8149
3.09 16,178
3.52 23,670
3.94 37,170
4.24 55,359
4.53 96,383
4.68 146,250
4.83 284,118
NOTE
All voltage and resistance values are approximate (+/- 20%).
Intake air temperature sensor is measured between Terminal
10 of [11] and system ground (Terminals 2 and 11 of [10]).
2002 Buell S3T: Fuel System
4.20
4.7 BREA-
TEMP °C TEMP °F
125 257
113 234.5
100 212
90 194
80 176
60 140
40 104
30 86
20 68
10 50
0 32
-10 14
-20 -4
4-57