
RENR5622 147
Troubleshooting Section
Expected Result:
The throttle assembly operates smoothly without
excessive drag. The throttle assembly returns to the
low idle posit
ion without assistance in less than one
second.
Results:
•
OK – The throttle assembly is operating correctly.
Proceed to Tes
tStep2.
•
Not OK – The throttle assembly is not operating
correctly.
Repair: Repair the throttle assembly or replace
the throttle
assembly. The throttle assembly
should operate smoothly without excessive drag.
The throttle assembly should return to the low
idle positio
n without assistance in less than one
second.
STOP.
Test Step 2. Check the Throttle Position
with Caterpillar Electronic Technician
(ET)
A. Connect Cat ET to the service tool connector.
Start Cat ET.
B. Turn the k eyswitch to the ON position.
C. Observe th
e throttle position reading on Cat ET.
D. Depress the throttle and release the throttle.
Expected Result:
The thrott
le position reads 0 percent when the throttle
pedal is released. The throttle position increases
to 100 percent when the throttle pedal is fully
depresse
d.
Results:
•
OK – The throttle position reads 0 percent when
the throttle pedal is released. The throttle position
increase
s to 100 percent when the throttle pedal is
fully depressed. The throttle position sensor is OK.
Repair: T
here may be an intermittent problem. If
the problem is intermittent, perform the diagnostic
functional test Troubleshooting, “Inspecting
Electri
cal Connectors”.
STOP.
•
Not OK – The throttle position does not read 0
percent when th
e throttle pedal is released. The
throttle position does not increase to 100 percent
when the throttle pedal is fully depressed. The
ECM is not rece
iving a correct signal f rom the
sensor. There may be a problem in the harness.
ProceedtoTestStep3.
Test Step 3. Check the 8 Volt Sensor
Supply at the Throttle Position Sensor
Connector
A. Turn the key
switch to the OFF position.
B. Disconnect the connector for the throttle position
sensor.
C. Turn the keyswitch to the ON position.
D. Measure the sensor supply voltage at the
connector between Terminal A and Terminal B.
Expected Result:
The voltag
e is 8.0 ± 0.4 VDC.
Results:
•
OK – The voltage is 8.0 ± 0.4 VDC. The supply
voltage is reaching the sensor. Proceed to Test
Step 4.
•
Not OK – The voltage is not 8.0 ± 0.4 VDC. The
supply vol
tage is not reaching the sensor. Proceed
to Test Step 7.
Test Step 4
. Check the Duty Cycle at the
Throttle
Position Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Remove wire F702-GN from Terminal C at the
sensor connector.
C. Turn the keyswitch to the ON position.
D. Measure t
he duty cycle between wire F702-GN
and Terminal B at the sensor connector.
Note: Set
the multimeter to “VDC”. Press t he “Hz”
button twice so that the % symbol is displayed.
E. Depress
the throttle and release the throttle.
F. Turn the keyswitch to the OFF position.
G. Reconnect all connectors and wires.
Expecte
dResult:
The duty cycle is between 6 and 10 percent when the
throttl
e is released. The duty cycle is between 85 and
94 percent when the throttle is fully depressed.