0127593 JOHNSON KEY, #77

Table 1
Diagnostic Codes Table    
Description    Conditions which Generate this Code    System Response    
190-8 Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period     The Electronic Control Module (ECM) detects a loss of signal from the primary speed/timing sensor for two seconds.
The ECM has been powered for at least three seconds.     The code is logged.
If equipped, the warning light will illuminate.
The ECM will use the signal from the secondary speed/timing sensor.
The engine will be derated. The engine will shut down if both of the speed-timing signals are lost.    
342-8 Secondary Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period     The ECM detects a loss of signal from the secondary speed/timing sensor for two seconds.
The ECM has been powered for at least three seconds.     The code is logged.
If equipped, the warning light will illuminate.
The loss of signal during start-up will prevent the engine from starting.
The ECM will use the signal from the primary speed/timing sensor.
. If both speed-timing signals are lost the engine will shut down.    The engine uses two engine speed/timing sensors. The primary crankshaft speed/timing sensor is located on the right hand side of the cylinder block close to the flywheel housing. The secondary pump speed/timing sensor is mounted on the fuel rail pump. The primary speed/timing sensor generates a signal by detecting the movement of the teeth that are on the speed/timing ring. The speed/timing ring is connected to the crankshaft. The ECM uses the engine speed/timing signal to calculate the position of the crankshaft. The signal is also used to determine the engine speed.The secondary speed/timing sensor is located in the fuel rail pump. The secondary speed/timing sensor generates a signal that is related to the camshaft position. The fuel rail pump is mechanically connected to the camshaft. The secondary engine speed/timing sensor detects the movement of the teeth on the speed/timing ring in the fuel rail pump. The ECM calculates the speed and the rotational position of the engine by using the signal. The secondary speed/timing sensor is required for starting purposes.During normal operation, the secondary speed/timing sensor is used to determine the engine timing. When the timing has been established, the primary speed/timing sensor is then used to determine the engine speed and the angular position.The primary sensor and the secondary sensor are interchangeable components. This will allow testing to determine if a speed/timing sensor is faulty.
Illustration 1 g01345702
The schematic for the speed/timing sensors
Illustration 2 g01325434
A typical view of the P2 connector (wire side) pin locations. (10) Speed/ Timing sensor supply (52) Crankshaft speed/timing sensor signal (53) Pump speed/timing sensor signal
Illustration 3 g01345706
A typical view of the P2 connector (ECM side) pin locations.
Illustration 4 g01325518
Typical view of the sensor locations on the C4.2 engine (1) Primary crankshaft speed/timing sensor (2) Secondary pump speed/timing sensor
Illustration 5 g01325522
Typical view of the sensor locations on the C6.4 engine (1) Primary crankshaft speed/timing sensor (2) Secondary cam/pump speed/timing sensor
Illustration 6 g01212995
Typical example of the speed/timing sensor (1) Supply (2) SignalTest Step 1. Inspect the Electrical Connectors and the Harness
Turn the keyswitch to the OFF position.
Illustration 7 g01325579
Typical engine ECM (1) P2 ECM connector (2) P1 ECM connector
Thoroughly inspect the P2 connector and the circuit that is associated with the suspect sensor. Refer to service Troubleshooting, "Electrical Connectors - Inspect".
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 serviceTroubleshooting, "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.
Check that the suspect sensor is installed correctly. Check that the suspect sensor is fully seated into the engine. Check that the sensor is securely latched.Expected Result:All of the 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 connectors and/or wiring are OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are Not OK.Repair: Repair the faulty connectors or the harness and/or replace the faulty connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly coupled.If a sensor must be replaced or the sensor must be reinstalled, complete all of the following tasks:
Lubricate the O-ring with clean engine lubricating oil.
Ensure that the plug for the sensor has a seal inside the connector body. If a seal is damaged or missing, replace the seal.
Ensure that the sensor is fully seated into the engine before tightening the bracket bolt.
Ensure that the connector is latched.
Ensure that the harness is correctly secured, and ensure that the harness is attached to the harness clip.Verify that the repair eliminates the problem.If applicable, use Caterpillar Electronic Technician (ET) to perform a wiggle test.STOPTest Step 2.