COVER 1351964 - Caterpillar

Illustration 2 g00938637
P1 ECM connector
Illustration 3 g00770282
P2 ECM connector
Fabricate a jumper wire with pins at both ends.
Use the jumper wire to short P35:A (Digital Sensor +8 VDC) and P35:C (Throttle Position) together.
Measure the resistance between P2:24 (Throttle Position) and P1:35 (Digital Sensor +8 VDC).
Move the one end of the jumper wire from P35:A (+8 VDC) to P35:B (Return). Leave the other end in P35:C (Signal).
Measure the resistance between P2:24 (Throttle Position) and P1:29 (Digital Return).
Remove the jumper wire and reconnect all of the connectors.Expected Result:The resistance is less than 10 Ohms for each measurement.Results:
OK - The harness is good. Proceed to Test Step 8.
Not OK - There is an open circuit or excessive resistance in the harness or the connectors.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 8. Check the Signal Frequency and the Duty Cycle at the ECM
Illustration 4 g00938637
J1/P1 breakout
Illustration 5 g00770282
J2/P2 breakout
Install a 7X-1715 Adapter Cable (Forty-Pin Breakout) and a 134-5195 Adapter Cable at the J1/P1 ECM connector.
Install a 7X-1715 Adapter Cable (Forty-Pin Breakout) and a 134-5195 Adapter Cable at the J2/P2 ECM connector.
Turn the keyswitch to the ON position.
Measure the frequency and the duty cycle between P2:24 (Throttle Position) and P1:29 (Digital Return) at the breakouts while you operate the throttle pedal.
Turn the keyswitch to the OFF/RESET position.Expected Result:The frequency is between 150 and 1000 Hz. The duty cycle is between 10 and 22 percent when the pedal is released. The duty cycle is between 75 and 90 percent when the pedal is fully depressed.Results:
OK - A valid sensor signal is reaching the ECM. Proceed to Test Step 9.
Not OK - There is an intermittent problem in the wiring harness or the connectors.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOPTest Step 9. Check the Status of the Throttle Position
Turn the keyswitch to the ON position.
Observe the status for "Throttle Position" on Cat ET while you operate the throttle pedal.Expected Result:The status reads approximately 0 percent when the throttle pedal is released. The status progressively increases to 100 percent when the throttle pedal is fully depressed.Note: This range can change depending on the adjustment of the throttle pedal assembly.Results:
OK - The throttle position sensor is working properly.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - A valid signal appears at the ECM, but the ECM is not reading the signal properly.Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM.STOPTest Step 10. Check the Supply Voltage at the ECM
Illustration 6 g00938637
J1/P1 breakout
Install a breakout T at the J1/P1 ECM connector.
Turn the keyswitch to the ON position.
Measure the voltage between P1:29 (Digital Return) and P1:35 (Digital Sensor +8 VDC) at the J1/P1 breakout.
Turn the keyswitch to the OFF/RESET position.Expected Result:The supply voltage is 8.0 0.5 VDC.Results:
OK - There is an open circuit or excessive resistance in the harness between the ECM and the sensor.Repair: Repair the circuit.Verify that the repair eliminates the problem.STOP
Not OK - The ECM does not appear to be producing the correct