0383464 JOHNSON CARBURETOR ASSEMBLY COMPLETE, Lower

Table 1
Diagnostic Codes Table    
Code and Description     Conditions which Generate this Code     System Response    
262-3 5 Volt Sensor DC Power Supply voltage above normal     The analog sensor supply voltage is above normal for two seconds.
The Electronic Control Module (ECM) has been powered for three seconds.     The code is logged.
All sensors are set to default values.    
262-4 5 Volt Sensor DC Power Supply voltage below normal     The analog sensor supply voltage is below normal for two seconds.
The ECM has been powered for three seconds.    
263-3 Digital Sensor Power Supply (8V Or 12V) voltage above normal     The digital sensor supply voltage is above normal for two seconds.
The ECM has been powered for three seconds.     The code is logged.
The sensor is set to a default value.    
263-4 Digital Sensor Power Supply (8V Or 12V) voltage below normal     The digital sensor supply voltage is below normal for two seconds.
The ECM has been powered for three seconds.    System OperationThe ECM supplies a regulated voltage of 5.0 0.2 VDC to the following sensors:
Engine oil pressure sensor
Atmospheric pressure sensor
Injection actuation pressure sensor
Intake manifold pressure sensor
Engine coolant temperature sensor
Engine oil temperature sensor
Fuel temperature sensorThe ECM supplies a regulated voltage of 8.0 0.4 VDC to the throttle position sensor.The supply voltage for the sensors is routed from the ECM to terminal A of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal B of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If any of the -3 diagnostic codes are active, it is possible that a sensor has been damaged. Repair the sensor supply and check for any active sensor diagnostic codes in order to determine if a sensor has failed.
Illustration 1 g01395313
Typical schematicTest Step 1. Inspect Electrical Connectors and Wiring
Remove electrical power from the ECM.
Illustration 2 g01408242
ECM (8) J1/P1 connectors (9) J2/P2 connectors
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01828456
P1 ECM connector (P1-29) Digital sensor return (P1-35) +8 V Sensor (P1-37) Injection actuation pressure (P1-30) Sensor return (P1-36) +5 V Sensor (P1-31) Engine oil temperature
Illustration 4 g01828457
P1 ECM connector (P2-24) Throttle position (P2-23) Turbocharger outlet pressure (P2-8) Engine oil pressure (P2-20) Atmospheric pressure (P2-9) Engine coolant temperature (P2-15) Fuel temperature
Illustration 5 g01159881
Sensor connector (A) +5 V or +8 V sensor supply (B) Sensor return (C) Signal
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with 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 for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Look for the following diagnostic codes:
262-3
262-4
263-3
263-4 Note: Wait at least 30 seconds in order for the diagnostic codes to become active.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic code is active.Repair: The problem is no longer present. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - A 262-3 or 262-4 diagnostic code is active at this time. Proceed to Test Step 3.
Not OK - A 263-3 or 263-4 diagnostic code is active at this time. Proceed to Test Step 5.Test Step 3. Disconnect the 5 Volt Sensor(s) and Monitor the Active Diagnostic Codes
Use this procedure for any 262 diagnostic codes.
Monitor the active diagnostic code screen on Cat ET while you disconnect each 5 Volt sensor at the sensor connector. Check for an active 262-3 code or an active 262-4 code.Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Disconnect the following sensors one at a time:
Injection actuation pressure sensor
Engine oil pressure sensor
Atmospheric pressure sensor
Turbocharger outlet pressure sensor
Engine coolant temperature
Fuel temperature
Engine oil temperature
Remove electrical power from the ECM.Expected Result:The diagnostic code deactivates when a particular sensor is disconnected.Results:
OK - The diagnostic code deactivates when a particular sensor is disconnected.Repair: Connect the suspect sensor. If the code returns, replace the sensor. Connect the connector(s). Verify that the problem is resolved.STOP
Not OK - The diagnostic code remains active after a sensor is disconnected. Leave the sensor disconnected. The sensor is not the cause of the diagnostic code. Proceed to Test Step 4.