CARTRIDGE GP-TURBOCHARGER 4N6860 - Caterpillar

System Operation Description:The Throttle Position Sensor (TPS) eliminates the mechanical throttle and governor linkages. The TPS utilizes the lever movement by the operator to send an electrical signal to the ECM for the engine. The signal from the TPS and the signal from the speed/timing sensors are processed by the ECM in order to control the engine speed.Ensure that all parameters are programmed properly.Remove the pins J3:34 and J3:35 (if applicable) from the customer connectors on both the PORT and STBD engines. This will ensure that each ECM will respond to the appropriate throttle signal.Proceed with this test if the following occurrence happens.
Desired Engine Speed does not change when the throttles are moved.Refer to the following test if the Desired Engine Speed changes as the throttles are moved.
Troubleshooting, "Engine Synchronize Switch Circuit - Test"
Illustration 1 g00879007
Table 1
Pin Assignment on the Sensor     Connection    
Pin A     Switched Positive Battery    
Pin B     Negative Battery Bus Bar    
Pin C     Throttle Position Signal    The output of the sensor is a constant frequency signal with a pulse width that varies with the throttle position. The pulse width measures the duty cycle. The Pulse Width Modulated signal (PWM) is expressed as a percentage of the duty cycle. This percentage is between 0 and 100 percent. The TPS will produce a minimum duty cycle when the throttle is released. The TPS will produce a maximum duty cycle when the throttle is fully actuated.
Illustration 2 g00751431
Duty Cycle
Illustration 3 g00751478
Definition of PWM
Illustration 4 g00766798
Percent of Throttle Position versus PWM Input
Table 2
Throttle Position     Duty Cycle     Nominal Duty Cycle    
Low idle     5-10%     8%    
High idle     90-95%     92%    PWM Input RequirementsThe following criteria are required for the correct operations of a throttle position sensor that is not Caterpillar:"Activepull up/pull down with output protection""Sensor stop"
Low stop 7.5% 2.5%
High stop 92.5% 2.5%"Output frequency"
Minimum of 300 Hz
Nominal of 500 Hz
Maximum of 700 Hz"High output voltage"
Minimum of 4.5 VDC
Maximum of 32 VDC"Low output voltage"
Minimum of -0.3 VDC
Maximum of 0.5 VDC"Sink current"
-1.5 mA"Source current"
-2.0 mANote: The sourcing driver must be capable of sinking 1.5 mA if the output voltage of the output driver is less than 13.0 VDC."Output linearity"
2.5 % duty cycle versus throttle lever position
Illustration 5 g00762874
Simulated Load for the ECM
Illustration 6 g00885265
SchematicTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Check the connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment. Pay close attention to the following areas:
J1/P1 ECM connector
J3/P3 Customer connector
J35/P35 Throttle Position Sensor (Port)
J35/P35 Throttle Position Sensor (STBD)Refer to Troubleshooting, "Electrical Connectors - Inspect" for more information.Expected Result:The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.Clear all logged diagnostic