FA1844 Force HEX BOLT, 1/4 - 20 X 2 3/8

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 Electronic Control Module (ECM) detects an incorrect frequency or an incorrect duty cycle on the throttle signal.     The code is logged.
The throttle position is set to a default value of 0.    The speed control provides a throttle signal and a droop signal to the engine's ECM. The output for rated speed is a pulse width modulated signal (PWM) at a constant frequency. The speed signal varies with the position of the speed adjust potentiometer. The output for droop is a PWM signal at a constant frequency. The droop signal varies with the position of the droop adjust potentiometer. The output signal is referred to as a duty cycle or as a PWM signal. The output signal is expressed as a percentage between 0 and 100 percent for the speed adjust and a percentage between 0 and 10 percent for the droop adjust.The ECM calculates the desired engine rpm from the rated speed signal and the droop signal. The rated speed signal is valid when the duty cycle is in the range of 5 to 95 percent. If the ECM determines that the rated speed signal is invalid, the engine rpm will be set to the programmed low idle.Note: Desired speed can be adjusted from 1369 to 1945 rpm for a 60 Hz system and from 1141 to 1621 rpm for a 50 Hz system.The droop signal is valid when the duty cycle is in the range of 15 to 85 percent. If the ECM determines that the droop signal is invalid, the engine will run with no droop which is referred to as isochronous mode.Some applications may choose not to use the speed control. Some applications may use a load sharing module. The load sharing module is configured to provide the engine control with a rated speed signal. The signal has the same characteristics as the above defined signal. Some of these load sharing modules cannot provide a signal until the engine is running. In these cases, perform troubleshooting while the engine is running.
Illustration 1 g01444314
Typical circuit with engine control
Illustration 2 g01444508
Location of the ECM connectors (1) J2/P2 ECM connectors (2) J1/P1 ECM connectors
Illustration 3 g01444318
P1 ECM connector (P1-10) Rated speed
Illustration 4 g01444319
P2 ECM connector (P2-66) Digital return (P2-69) Speed droopTest Step 1. Inspect Electrical Connectors and Wiring
Turn the Engine Control Switch (ECS) to the OFF position. Turn the main disconnect switch to the OFF position.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM.Expected Result:All 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.