Buell 2002 X1, Service Manual

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4-58 2002 Buell X1: Fuel System
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TROUBLE CODE 15 4.20
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
DiagnosticTips
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 to locate intermittents. If
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.
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 4.7 BREA-
KOUT BOX.
2. Use HARNESS CONNECTOR TEST KIT (Part No. HD-
41404), gray socket probes and patch cord.
3. Use HARNESS CONNECTOR TEST KIT (Part No. HD-
41404), 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.
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]).
Table 4-18. Intake Air Temperature
Sensor Specifications
VOLTS RESISTANCE TEMP °C TEMP °F
0.49 1086 125 257
0.68 1561 113 234.5
0.86 2077 100 212
1.13 2920 90 194
1.40 3889 80 176
2.25 8149 60 140
3.09 16,178 40 104
3.52 23,670 30 86
3.94 37,170 20 68
4.24 55,359 10 50
4.53 96,383 0 32
4.68 146,250 -10 14
4.83 284,118 -20 -4