0439189 JOHNSON CARBURETOR ASSY., Lower

Illustration 1 g01290036
Schematic for the engine speed/timing sensors
Test Step 1. CHECK FOR DIAGNOSTIC CODES
Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to electronic troubleshooting Troubleshooting, "Electronic Service Tools".
Restore the electrical power to the ECM.
Start the engine and run the engine until the engine is at normal operating temperature.Note: If the engine will not start, monitor the engine rpm on Cat ET while the engine is being cranked. Another battery may be needed while the engine is being cranked.
Look for these codes on Cat ET:Note: Wait at least 30 seconds for any codes to become active.
190-08
342-08Expected Result:One or both of the diagnostic codes that are listed above are logged or active.Note: If the engine will not start and Cat ET displayed 0 rpm during cranking, select "No Engine rpm".Results:
No Engine rpm - Engine rpm is not indicated on Cat ET. Proceed to Test Step 2.
08 code - There is an active diagnostic code or a logged diagnostic code for the engine speed/timing sensor. Proceed to Test Step 4.Test Step 2. CHECK THE INSTALLATION OF THE SENSOR
Remove the electrical power from the ECM.
Illustration 2 g01248724
Engine speed/timing sensors
(1) Bracket
(2) Primary speed/timing sensor
(3) Mounting plate
(4) O-ring seals
(5) Bracket
(6) Secondary speed/timing sensor
Remove the suspect engine speed/timing sensor from the engine.
Ensure that O-ring seals (4) are installed on the sensor and on the mounting plate. Ensure that the O-ring seals are free of damage.
Ensure that mounting brackets are holding the sensor securely to the engine and that the brackets are not damaged or bent.Expected Result:All the O-ring seals are properly installed and free of damage. The bracket is free of damage.Results:
OK - The O-ring seals are properly installed. The bracket is free of damage.Repair: Perform the following procedure to install a sensor:
Lubricate the O-ring seals with oil.
Fully seat the sensor into the housing.
Tighten the bracket bolt.
Connect the connector and verify that the latch tab of the connector is latched on both sides.
Ensure that the harness is properly secured, and ensure that the harness is attached to the harness clip. Proceed to Test Step 3.
Not OK - At least one of the sensor assembly components is not OK.Repair: Replace the component.Note: Do not switch the positions of the sensors. The sensors are not interchangeable. A timing calibration is not required when the sensors are replaced.
Lubricate each O-ring with oil.
Fully seat the sensor into the housing.
Tighten the bracket bolt.
Connect the connector and verify that the latch tab of the connector is latched on both sides.
Ensure that the harness is properly secured, and ensure that the harness is attached to the harness clip.Verify that the problem is resolved.STOPTest Step 3. INSPECT THE ELECTRICAL CONNECTORS AND THE WIRING
Illustration 3 g01248737
Engine speed/timing sensors (typical example)
(7) J44/P44 connectors for the primary engine speed/timing sensor
(8) J20/P20 connectors for the secondary engine speed/timing sensor
(9) J2/P2 ECM connectors
Thoroughly inspect connectors (5), (6), (7), and (8). Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Illustration 4 g01248836
ECM connections for the engine speed/timing sensors
(P1-12) Secondary engine speed/timing −
(P1-18) Secondary engine speed/timing +
(P2-4) Primary engine speed/timing −
(P2-39) Primary engine speed/timing +
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine speed/timing sensors.
Check the torque of the allen head screws for the ECM connectors. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from each sensor back to the ECM.Expected Result:All the connectors, pins, and sockets are coupled and/or inserted. 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 4.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all the seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminates the problem.STOPTest Step 4. MEASURE THE SENSOR RESISTANCE THROUGH THE ENGINE HARNESS
Disconnect the J1/P1 and J2/P2 ECM connectors.
If you are troubleshooting a problem with the primary engine speed/timing sensor, perform the following procedure:
Measure the sensor resistance between P2-39 (Primary engine speed/timing +) and P2-4 (Primary engine speed/timing -).
Check for an intermittent open circuit or for a short circuit by moving the harness while you take the resistance measure