
148 RENR5622
Troubleshooting Section
Results:
•
OK – A valid duty cycle is present at the sensor
connector. Proceed to Test Step 5.
•
Not OK – A valid duty cycle is not present at the
sensor connector.
Repair: Replace the throttle position sensor. Verify
that the new sensor is operating correctly.
STOP.
Test Step 5. Ch
eck the Duty Cycle at the
ECM
A. Remove wire F702-GN from P1-10 at the ECM
connector P1
.
B. Turn the k eyswitch to the ON position.
C. Measure the duty cycle between wire F702-GN
and P1-5 of ECM connector J1/P1.
Note: Set the multimeter to “VDC”. Press the “Hz”
button twice so that the % symbol is displayed.
D. Depress the throttle and release the throttle.
E. Turn the key
switch to the OFF position.
F. Reconnect all connectors and wires.
Expected Result:
The duty cyc
le is between 6 and 10 percent when the
throttle is released. The duty cycle is between 85 and
94 percent when the throttle is fully depressed.
Results:
•
OK –Avalidd
uty cycle is present at the ECM
connector. Proceed to Test Step 6.
•
Not OK – A val
id duty cycle is not present at the
ECM connector.
Repair: The
re is a problem in the wiring and/or
connectors between the ECM and the throttle
position sensor. Repair the connectors or wiring
and/or rep
lace the connectors or wiring.
STOP.
Test Step 6. Check the Throttle Position
with the Cat ET
A. Turn the k
eyswitch to the ON position.
B. Observe the throttle position on Cat ET.
C. Depress the throttle and release the throttle.
D. Turn the keyswitch to the OFF position.
Expected Resul
t:
The throttle position reads 0 percent when the throttle
pedal is relea
sed. The throttle position increases
to 100 percent when the throttle pedal is fully
depressed.
Note: The throttle position on Cat ET will not match
the percent duty cycle on the multimeter.
Results:
•
OK – 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 depr
essed. The throttle position sensor is
OK. There is an intermittent problem in the wiring
and/or connectors between the ECM and the
throttle po
sition sensor.
Repair: If the problem is intermittent, perform
the diagnos
tic functional test Troubleshooting,
“Inspecting Electrical Connectors”.
STOP.
•
Not OK – The throttle position does not read 0
percent whe
n the throttle pedal is released. The
throttle position does not increase to 100 percent
when the throttle pedal is fully depressed.
Repair: The ECM is not reading the throttle
position sensor signal correctly. Replace the ECM.
Refer to th
e diagnostic procedure T roubleshooting,
“Replacing the ECM.”.
STOP.
Test Step 7. Check the 8 Volt Supply
Voltage at the ECM
A. Disconnect the J1/P1 ECM connector.
B. Fabricat
e two jumper wires that are long enough
to be used to measure the supply voltage at the
ECM connectors. Crimp connector sockets to one
end of ea
ch jumper wire.
C. Remove the wires from terminal locations P1-4 (8
Vsensor
supply) and P1-60 (sensor return). Install
a jumper wire into each of these terminal locations.
D. Connect
the J1/P1 ECM connector.
E. Restore electrical power to the engine ECM.