GEAR (43 & 13 Teeth) 2V0817 - Caterpillar

System Operation Description:Use this procedure in order to troubleshoot the electrical system if a problem is suspected with the throttle position signal. Use this procedure 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 signal abnormal The Electronic Control Module (ECM) detects an abnormal throttle signal for five seconds. The code is logged. 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.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 can not provide a signal until the engine is running. In these cases, troubleshooting should be performed while the engine is running.
Illustration 1 g01218219
Typical schematic
Illustration 2 g01218220
P1 ECM connector
(P1-5) Digital return
(P1-10) Throttle signal
Illustration 3 g01218221
P2 ECM connector
(P2-69) Droop signal
Illustration 4 g01218222
"Connector "A""
(Terminal 12) Droop signal
(Terminal 14) Throttle signal
(Terminal 25) Digital return
Illustration 5 g01234146
Location of ECM connectors
Illustration 6 g01218225
Customer connector
(Terminal 36) Throttle signal
(Terminal 37) Potentiometer Terminal 1
(Terminal 38) Potentiometer Terminal 2
(Terminal 39) Potentiometer Terminal 3 Test Step 1. Inspect Electrical Connectors and Wiring
Turn the ECS to the OFF position.
Thoroughly inspect the ECM connectors. Inspect all of the other connectors for the circuit. 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 ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" 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