EXTENSION-TORQUE WRENCH 9U5932 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the throttle signal or if the diagnostic code in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Description Conditions which Generate this Code System Response
91-8 Throttle Position Sensor abnormal frequency, pulse width, or period The Engine's Electronic Control Module (ECM) detects a sensor frequency that is less than 150 Hz or a sensor frequency that is greater than 1000 Hz for two seconds.
or
The ECM detects a duty cycle that is less than 5 percent or a duty cycle that is greater than 95 percent for one second. The code is logged.
The throttle signal defaults to a zero percent duty cycle (low idle). The customer supplied throttle signal provides a 500 Hz pulse width modulated signal (PWM) to the engine's ECM. The signal is expressed as a percentage between 1 and 100 percent. The signal will produce a duty cycle of 5 to 10 percent at the low idle setting. The signal will produce a duty cycle of 90 to 95 percent at the high idle setting. The percent duty cycle is translated by the ECM into a throttle position of 0 to 100 percent.
Illustration 1 g01938834
Typical schematic
Illustration 2 g01259643
P1 ECM connector
(P1-10) Throttle
Illustration 3 g01259644
Connector "A"
(Terminal 14) Throttle
Illustration 4 g01259645
Connector "F"
(Terminal 29) Throttle
Illustration 5 g01234146
Location of ECM connectors
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the breaker for the ECM to the OFF position.
Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the proper procedure for inspecting system wiring.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/or wiring.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.STOPTest Step 2. Check the Throttle Signal at Connector G on the Remote Junction Box
Remove the wire for the throttle from terminal 29 on connector G in the remote junction box.
Connect a multimeter between the wire that was removed in the previous test step and engine ground.
Set the multimeter to "VDC". Press the "Hz" button twice so the "%" symbol is displayed.
Monitor the duty cycle as you move the throttle from the low idle position to the highest engine speed setting.
Reconnect all wires. Expected Result:The duty cycle is between 5 and 10 percent at the low idle position and