0391064 JOHNSON PROPELLER 10 X 17

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 engine's ECM detects a pattern for the timing ring that is incorrect for five seconds.     The secondary engine speed/timing signal will be used if the primary engine speed/timing signal is lost.
The code is logged if the pattern from the timing ring returns for five seconds.    
342-8 Secondary Engine Speed Sensor abnormal frequency, pulse width, or period     The engine's ECM detects a pattern for the timing ring that is incorrect for five seconds.     The primary engine speed/timing signal will be used if the secondary engine speed/timing signal is lost.
The code is logged if the pattern from the timing ring returns for five seconds.    The timing signal is created as the timing reference gear rotates past the engine speed/timing sensor. The timing reference gear is mounted on the rear of the right camshaft. A unique tooth pattern on the timing reference gear allows the ECM to determine the crankshaft position, the camshaft position, engine rotation, and engine rpm.The engine speed/timing sensor generates a signal to the ECM as each tooth passes the sensor. The ECM counts the number of signals in order to determine the engine rpm. The ECM memorizes the pattern of the signals. The ECM compares that pattern to a standard pattern in order to determine the crankshaft position. The ECM uses this information to determine the position of the No. 1 cylinder. The ECM then triggers each fuel injector to fire in the correct firing order and at the correct time. The actual timing and duration of each injection is determined by the ECM. The ECM uses engine rpm and engine load to determine the timing and duration of injection. The loss of the signal from the engine speed/timing sensor generates a diagnostic code. The loss of the signals from the primary engine speed/timing sensor and from the secondary engine speed/timing sensor triggers the termination of the signals to the fuel injectors by the ECM.If the primary engine speed/timing sensor fails, the ECM will use the secondary engine speed/timing sensor until electrical power is removed from the ECM. To prevent any unnecessary down time, repair the primary engine speed/timing sensor at the earliest possible convenience.
Illustration 1 g01248850
Typical schematic
Illustration 2 g01251226
Typical locations of engine speed/timing sensors on 6 and 8 cylinder engines (1) Secondary engine speed/timing sensor (2) Primary engine speed/timing sensor
Illustration 3 g01257640
Typical locations of engine speed/timing sensors on 12 and 16 cylinder engines (3) Primary engine speed/timing sensor (4) Secondary engine speed/timing sensor
Illustration 4 g01164614
P1 ECM connector (P1-32) Primary engine speed/timing + (P1-33) Primary engine speed/timing - (P1-40) Secondary engine speed/timing + (P1-41) Secondary engine speed/timing -
Illustration 5 g01248856
Connector for the railR-C7/K-C7 connector or RH-C1/K-C8 connector (Terminal 25) Primary engine speed/timing - (Terminal 26) Primary engine speed/timing + (Terminal 27) Secondary engine speed/timing - (Terminal 28) Secondary engine speed/timing +
Illustration 6 g01234146
Location of ECM connectorsTest Step 1. Check for an "ACTIVE" Diagnostic Code
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the local/remote switch on the control panel to the LOCAL position.
Check for one of the following diagnostic codes on Cat ET:
190-8
342-8Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: The problem is no longer present. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - A diagnostic code is active. Proceed to Test Step 2.Test Step 2. Measure the Resistance of the Suspect Engine Speed/Timing Sensor at the Sensor's Connector
Turn the local/remote switch on the control panel to the OFF/RESET position.
Disconnect the connector for the suspect engine speed/timing sensor.
Measure the resistance between terminal 1 and terminal 2 at the sensor connector.Expected Result:The resistance is between 600 Ohms at a temperature of −40 °C (−40 °F) and 1800 Ohms at a temperature of 120 °C (248 °F).Results:
OK - The resistance is correct. Proceed to Test Step 3.
Not OK - The resistance is not correct.Repair: The engine speed/timing sensor has a short or an open. Replace the engine speed/timing sensor. Verify that the diagnostic code is no longer active.STOPTest Step 3. Measure the Resistance of the Suspect Engine Speed/Timing Sensor at the Connector for the Rail
Reconnect the suspect engine speed/timing sensor to the harness.
Disconnect the connector for the rail.
Measure the resistance between the terminals for the suspect engine speed/timing sensor at the connector for the rail. Refer to Illustration 1 for the correct terminals for the suspect engine speed/timing sensor.Expected Result:The resistance is between 600 Ohms at a temperature of −40 °C (−40 °F) and 1800 Ohms at a temperature of 120 °C (248 °F).Results:
OK - The resistance is correct. Proceed to Test Step 4.
Not OK - The resistance is not correct.Repair: The open or the short is in the harness between the connector for the rail and the connector for the suspect engine speed/timing sensor. Repair the connectors and/or wiring or replace the connectors and/or wiring.STOPTest Step 4. Measure the Resistance of the Suspect Engine Speed/Timing Sensor at the ECM Connector
Reconnect the connector for the rail.