SEAL 5M3374 - Caterpillar

System Operation Description:The throttle position sensor eliminates the mechanical throttle and governor linkages. The sensor that is installed depends on the engine's configuration.
Illustration 1 g01123466
Electronic throttle position sensor
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Throttle position sensor with a lever
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Throttle position sensor with a knob
Refer to Illustration 4. Pulse Width Modulation (PWM) is used to provide the throttle position to the ECM. The duty cycle varies with the throttle position. The signal has a low duty cycle when the throttle is at low idle. The signal has a high duty cycle when the throttle is at high idle. The Electronic Control Module (ECM) processes the signal in order to control the engine speed.
Illustration 4 g01122143
Duty cycle versus throttle position
The signal from the throttle position sensor has a specific frequency. The frequency of the signal must be between 150 Hz and 1050 Hz or the ECM will activate a 91-08 diagnostic code.
Illustration 5 g01213002Schematic for the throttle position sensorTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
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Engine view (typical example)
(1) J1/P1 ECM connectors
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Engine view (typical example)
(2) J61 customer connector
Thoroughly inspect connectors (1) and (2). Also, inspect the connector for the throttle position sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
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P1 terminal that is associated with the throttle position sensor
(P1-66) Throttle position signal
Illustration 9 g01213033
Terminal location at the P61 customer connector that is associated with the throttle position sensor
(10) Throttle position signal
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the throttle position sensor.
Check the allen head screw on each ECM connector for the proper torque. Also, check the allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and wiring for abrasions and for pinch points from the throttle position sensor to the ECM and from the throttle position sensor to the keyswitch and the engine ground. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The wiring and the connectors are OK. Proceed to Test Step 2.
Not OK - There is a problem with the wiring and/or the connectors.Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all of the seals are in good repair. Verify that the repair eliminates the problem.STOPTest Step 2. Check for Supply Voltage at the Throttle Position Sensor
Disconnect the P403 connector.
Turn the keyswitch to the ON position.
Measure the voltage between terminals P403-A and P403-B. Expected Result:The supply voltage is at least 11 VDC for a 12 volt system. The supply voltage is at least 22 VDC for a 24 volt system.Results:
OK - The supply voltage is within specifications. The supply voltage is reaching the sensor. Proceed to Test Step 3.
Not OK - The supply voltage is incorrect.Repair: The configuration of the wiring between the keyswitch and the throttle position sensor depends on the engine's configuration. The problem could