BODY-VALVE 8N9072 - Caterpillar

System Operation Description:Use this procedure in order to troubleshoot the electrical system if a problem is suspected with the throttle 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 Sensor abnormal frequency, pulse width, or period The Electronic Control Module (ECM) detects an abnormal throttle signal for five seconds. The code is logged. The direct fuel control mode enables the engine to be controlled by an external governor. You must install the components of the signal converter for the direct fuel control in order to operate in direct fuel control mode. The configuration parameter must be programmed to "ON" in order for the ECM to respond properly to the external governor.The input to the signal converter is a 0 to 200 mA signal. The signal is received from the external governor. The output signal from the signal converter is a Pulse Width Modulated signal (PWM).The output signal varies with the current to the signal converter. The ECM calculates the desired fuel from the PWM signal.The duty cycle for a valid signal is between 5 and 95 percent. If an invalid signal is received, the engine will automatically be set to a minimum fuel setting and the engine will shut down.The following functions are not used in direct fuel control mode.
Low idle
Crank terminate speed
Cooldown speed
Illustration 1 g01030195
Typical example
Illustration 2 g01444508
Location of the ECM connectors
(1) J2/P2 ECM connectors
(2) J1/P1 ECM connectors
Illustration 3 g01241475
P1 ECM connector
(P1-10) Desired fuel
(P1-05) Digital return Test Step 1. Inspect Electrical Connectors and Wiring
Turn the Engine Control Switch (ECS) to the OFF/RESET position. Turn the main disconnect switch to the OFF position.
Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors in 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 connector that are associated with the circuit.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
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 are OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 2. Check the Current Input to the Signal Converter
Turn the main disconnect switch to the ON position. Turn the ECS to the STOP position.
Measure the current to the signal converter. Note: Some external governors may only be able to output approximately 150 mA. This should not be seen as a problem with the external governor.Expected Result:The current range is between 0 and 200 mA.Results:
OK -