CORE AS-RADIATOR 2040996 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system 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 speed control is used to provide a throttle signal to the engine control. The output for rated speed is a pulse width modulated signal. The output signal is expressed as a percentage between 0 and 100 percent.The ECM calculates the desired engine speed. The desired engine speed is produced by the signal from the rated speed setting. The rated speed signal is valid when the duty cycle is in the range of 5 to 95 percent. If the rated speed signal is invalid, the engine will be set to the low idle.
Illustration 1 g01287955
Typical schematic
Illustration 2 g01287957
P1 ECM connector (P1-10) Primary throttle
Illustration 3 g01285750
Location of ECM connectorsTest Step 1. Inspecting Electrical Connectors and Wiring
Turn the "main disconnect switch (MDS)" to the OFF position.
Thoroughly inspect the ECM connector J1/P1. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
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 harness and the wiring for abrasion and pinch points.Expected Result:The components and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - The wiring and connectors are OK. Proceed to Test Step 2.
Not OK - The wiring and/or connectors need repair.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 2. Check the Throttle Position on Caterpillar Electronic Technician (ET)
Turn the "MDS" to the ON position.
Observe the position of the throttle on Cat ET.
Adjust the throttle from the lowest setting to the highest setting.
Monitor the position of the throttle on Cat ET.Expected Result:The throttle position on Cat ET reads 0 percent at the lowest setting and 0 to 100 percent as the throttle is adjusted.Results:
OK - The throttle signal is being received by the ECM.Repair: There may be an intermittent problem. If the problem is intermittent perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - The throttle position on Cat ET does not change correctly. Proceed to Test Step 3.Test Step 3. Check the Throttle Signal at the Main Junction Box
Turn the "MDS" to the OFF position.
Remove wire F702-RD/BK to the ECM from terminal TBI-7 in