0337786 JOHNSON GROMMET

Illustration 1 g00839950
Typical schematic
Illustration 2 g01089290
P1 ECM connector (P1-14) Throttle backup switch (P1-29) Digital return (P1-35) 8 V digital supply
Illustration 3 g01091122
P2 ECM connector (P2-24) Throttle positionTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Thoroughly inspect the connectors J1/P1 and J2/P2 for the ECM. Inspect all of the other connectors. 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 of 6.0 N m (55 lb in).
Check the customer connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
Check the harness and the wiring for abrasion and for pinch points.Expected Result:The connectors and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - The connectors and wiring are okay. Proceed to Test Step 2.
Not OK - The connectors and/or wiring need repair.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 2. Check for Active Diagnostic Codes
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.Note: Wait at least 15 seconds in order for the diagnostic codes to become active.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: The problem may have been solved during the preceding inspection of the harness and connectors. The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - A 091-08 diagnostic code is active. Proceed to Test Step 3.Test Step 3. Inspect the Throttle AssemblyInspect the throttle assembly for damaged components.Expected Result:The throttle assembly should operate smoothly without excessive drag. The throttle assembly should return to the low idle position without assistance in less than one second.Results:
OK - The throttle assembly is operating correctly. Proceed to Test Step 4.
Not OK - The throttle assembly is not operating correctly.Repair: Repair the throttle assembly or replace the throttle assembly. The throttle assembly should operate smoothly without excessive drag. The throttle assembly should return to the low idle position without assistance in less than one second.STOPTest Step 4. Check the Throttle Position with Cat ET
Connect Cat ET to the cab service tool connector J42. Start Cat ET.
Turn the circuit breaker for the battery to the ON position.
Turn the keyswitch to the ON position. The engine should be off.
Observe the throttle position reading on Cat ET.
Depress the throttle and release the throttle.Expected Result:The throttle position reads 0 percent when the throttle pedal is released. The throttle position increases to 100 percent when the throttle pedal is fully depressed.Results:
OK - The throttle position reads 0 percent when the throttle pedal is released. The throttle position increases to 100 percent when the throttle pedal is fully depressed. The throttle position sensor is okay.Repair: There may be an intermittent problem. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - The throttle position does not read 0 percent when the throttle pedal is released. The throttle position does not increase to 100 percent when the throttle pedal is fully depressed. The ECM is not receiving a correct signal from the sensor. There may be a problem in the harness. Proceed to Test Step 5.Test Step 5. Check the Sensor Supply Voltage at the Throttle Position Sensor Connector
Turn the keyswitch to the OFF position.
Disconnect the connector for the throttle position sensor J35/P35.Note: If you remove the sensor common from a sensor, an open circuit diagnostic code will be generated for that sensor. Troubleshoot the original code. Delete the logged diagnostic code when you are finished.
Turn the keyswitch to the ON position. The engine should be off.
Measure the sensor supply voltage at the connector between P35-A and P35-B.Expected Result:The voltage is 8.0 0.4 VDC.Results:
OK - The voltage is 8.0 0.4 VDC. The supply voltage is reaching the sensor. Proceed to Test Step 6.
Not OK - The voltage is not 8.0 0.4 VDC. The supply voltage is not reaching the sensor. Proceed to Test Step 9.Test Step 6. Check the Signal Frequency and the Duty Cycle at the Throttle Position Sensor Connector
Turn the keyswitch to the OFF position.
Remove wire F702-GN from P35-C at the sensor connector.
Turn the keyswitch to the ON position. The engine should be off.
Measure the frequency and the duty cycle between wire F702-GN and P35-B.Note: Set the multimeter to "VDC". Press the "Hz" button twice so that the % symbol is displayed.
Depress the throttle and release the throttle.
Turn the keyswitch to the OFF position. The engine should be off.
Reconnect all connectors and wires.Expected Result:The frequency is between 150 and 1000 Hz.The duty cycle is between 10 and 22 percent when the throttle is released. The duty cycle should be between 75 and 90 percent when the throttle is fully depressed.Results: