PINION (17 Teeth) 3V5148 - 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 signal abnormal 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 mode in order to operate in direct fuel control mode. The configuration parameter "Direct Fuel Control Mode" 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 to the ECM 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.You have a valid signal when the duty cycle 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 droop is not used for the direct fuel control mode. Disconnecting the droop at the ECM will not affect engine operation.
Illustration 1 g01218198
Typical example
Illustration 2 g01218199
P1 ECM connector
(P1-10) Throttle signal
(P1-5) Digital return
Illustration 3 g01234146
Location of ECM connectors
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 corrosion, of abrasion, and of pinch points.Results:
OK - The connectors and wiring are 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.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Current Input
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 - The current is within the correct range. Proceed to Test Step 3.
Not OK - The current is not within the correct range.Repair: Replace the external