3176C Engine for the R1600G and the R1700G Load Haul Dumps Speed Control (Remote Throttle) - Test Caterpillar


Speed Control (Remote Throttle) - Test
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System Operation Description:

Use this procedure to troubleshoot the electrical system if a problem is suspected with the remote throttle control or if the diagnostic code in Table 1 is active or easily repeated.

Table 1
Diagnostic Codes Table    
Code and Description     Conditions which Generate this Code     System Response    
91-8 Throttle Position Sensor abnormal frequency, pulse width, or period     The Electronic Control Module (ECM) detects an incorrect duty cycle on the throttle signal. The duty cycle is less than 5 percent or the duty cycle is greater than 95 percent.     The code is logged. The ECM flags the throttle position as invalid data and a default value of zero percent is used. The engine speed is limited to low idle.    

The remote throttle control provides the throttle signal to the ECM when the remote control system is used. The output from the remote throttle control is a pulse width modulated signal (PWM) that varies with the position of the remote throttle control. The remote throttle control produces a minimum duty cycle in the lowest setting and a maximum duty cycle in the highest setting. When the remote throttle control is at the lowest setting, the ECM translates the output of the remote throttle control to a throttle position of 0 percent. When the remote throttle control is at the highest setting, the ECM translates the output signal to a throttle position of 100 percent.




Illustration 1g01410644

Typical schematic for a R1600G machine




Illustration 2g01411042

Typical schematic for a R1700G machine

Test Step 1. Inspect the Electrical Connectors and the Wiring

  1. Turn the keyswitch to the OFF position.

  1. Remove electrical power from the ECM.



    Illustration 3g01139425

    ECM

    (1) J1/P1 connectors

    (2) J2/P2 connectors

  1. Thoroughly inspect the J1/P1 ECM connector. Inspect all of the connectors that are associated with the circuit.

    Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.




    Illustration 4g01410625

    P1 ECM connector

    (P1-31) Remote throttle




    Illustration 5g01410631

    CN24 or CN28Machine connector

    (CN24-38 or CN28-38) Remote throttle

  1. Perform a 45 N (10 lb) pull test on each of the wires in the circuit.

  1. Check the allen head screw from each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.

  1. Check the harness and the wiring for abrasion and for pinch points.

Expected Result:

All of the 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 harness and connectors appear to be OK. Proceed to Test Step 2.

  • Not OK - The connectors and/or wiring are 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.

    STOP

Test Step 2. Check the Status for "Throttle Position"

  1. Connect AVSpare Electronic Technician (ET) to the service tool connector.

  1. Restore electrical power to the ECM.

  1. Turn the keyswitch to the ON position.

  1. Observe the status for "Throttle Position" on Cat ET while you operate the remote throttle control through the entire range of travel.

Expected Result:

The status is zero percent when the remote throttle control is set to the lowest setting. The status progressively increases to 100 percent when the remote throttle control is set to the highest setting.

Results:

  • OK - The remote throttle control is working properly.

    Repair: There may be an intermittent electrical problem with the harness or the connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.

    STOP

  • Not OK - The throttle position that is displayed on Cat ET does not correspond to the movement of the remote throttle control. Proceed to Test Step 3.

Test Step 3. Check the Signal Frequency and the Duty Cycle of the Remote Throttle Control

  1. Perform the following test steps if you are troubleshooting a R1600G machine.

    1. Remove the signal wire for the remote throttle from connector CN103-18. Remove the wire from the harness side of the connector.

    1. Turn the keyswitch to the ON position.

    1. Measure the frequency and the duty cycle between connector CN103-18 and engine ground while you operate the remote throttle control.

    1. Turn the keyswitch to the OFF position.

    1. Restore the wires to the original configuration.

  1. Perform the following test steps if you are troubleshooting a R1700G machine.

    1. Remove the signal wire for the remote throttle from the connector to the remote control. Remove the wire from the harness side of the connector.

    1. Turn the keyswitch to the ON position.

    1. Measure the frequency and the duty cycle between the terminal for the signal wire and engine ground while you operate the remote throttle control.

    1. Turn the keyswitch to the OFF position.

    1. Restore the wires to the original configuration.

Expected Result:

The frequency is between 150 and 1000 Hz. The duty cycle is between 5 and 95 percent.

Results:

  • OK - The frequency and the duty cycle are within specifications for the entire range of the remote throttle control. Proceed to Test Step 4.

  • Not OK - The frequency or the duty cycle are not within specifications.

    Repair: A valid signal is not present at the connector to the remote control. Repair the wiring to the remote throttle control or repair the remote throttle control. Verify that the repair eliminates the problem.

    STOP

Test Step 4. Check the Duty Cycle at the ECM

  1. Remove the signal wire for the remote throttle control from ECM connector P1-31.

  1. Turn the keyswitch to the ON position.

  1. Measure the duty cycle for the remote throttle control at the ECM connector. Measure the duty cycle between the wire that was removed from P1-31 and terminal P1-29 while you operate the remote throttle control.

  1. Turn the keyswitch to the OFF position.

Expected Result:

The duty cycle is between 5 and 95 percent.

Results:

  • OK - The duty cycle is within specifications for the entire range of the remote throttle control.

    Repair: A valid signal appears at the ECM, but the ECM is not reading the signal properly. Replace the ECM. Refer to Troubleshooting, "ECM - Replace" for complete instructions. Verify that the repair eliminates the problem.

    STOP

  • Not OK - The frequency and the duty cycle are not within specifications.

    Repair: There is not a valid signal at the ECM connector. Repair the signal wire between the connector to the remote control and the ECM. Verify that the repair eliminates the problem.

    STOP

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