0901889 JOHNSON SCREW,Stern brackets

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 governor that is supplying the controlling current.Repair CompleteTest Step 3. Check the Voltage at the Signal Converter
Connect one probe of the voltmeter to the +Battery terminal at the signal converter.
Connect one probe of the voltmeter to the −Battery terminal at the signal converter. Expected Result:The voltage measures 24 3 VDC.Results:
OK - The voltage measures 24 3 VDC. Proceed to Test Step 4.
Not OK - The voltage does not measure 24 3 VDC.Repair: Check the wiring and/or the connectors that are between the battery and the signal converter. Repair the wiring and/or connectors.Repair CompleteTest Step 4. Check the Desired Fuel Position
Connect Caterpillar Electronic Technician (ET) to the service tool connector. Start Cat ET.
Turn the ECS to the STOP position.
Observe the throttle position reading on Cat ET.
Vary the current to the signal converter. Expected Result:The throttle position on Cat ET varies from 5 percent to 95 percent as the current input is adjusted from 0 mA to 200 mA.Results:
OK - The throttle position on Cat ET corresponds with the current input.Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - The throttle position does not correspond to the current input. Proceed to Test Step 5.Test Step 5. Check the Hardware
Remove the signal wire from the signal converter.
Set the multimeter to "VDC".
Press the "Hz" button twice so that the "%" symbol is displayed.
Place one probe on the signal terminal of the signal converter.
Place the other probe on the −Battery terminal of the signal converter.
Monitor the output of the percent duty cycle from the signal converter.
Adjust the current input from a low current setting to a high current setting. Expected Result:The duty cycle is between 3 and 5 percent at the low setting and above 60 percent at the high setting.Results:
OK - The correct signal is being supplied by the signal converter. Proceed to Test Step 6.
Not OK - The duty cycle is not correct on the multimeter.Repair: Replace the signal converter.Repair CompleteTest Step 6. Check the ECM
Turn the ECS to the STOP position.
Replace the wire of the desired fuel output on the signal converter.
Set the multimeter to "VDC".
Press the "Hz" button twice so that the "%" symbol is displayed.
Measure the signal between P1-10 Throttle signal and P1-5 Digital return.
Monitor the output of the percent duty cycle on the multimeter.
Monitor the percent throttle position on Cat ET.
Vary the input current to the signal converter. Expected Result:The duty cycle is between 3 and 5 percent at the low setting and above 60 percent at the high setting. The percent throttle position is between 5 and 85 percent.Results:
OK - The duty cycle and the throttle position are correct.Repair: Check the system for any diagnostic codes.STOP
Not OK - Duty Cycle - The duty cycle is not correct.Repair: There is a problem in the wiring between P1-10 and the signal converter.STOP
Not OK - Throttle Position - The duty cycle is OK. The throttle position on Cat ET is incorrect.Repair: Replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".STOP