815950 1 Mercruiser BUSHING

Table 1
Event Code
Description Conditions which Generate this Code System Response
190-8 Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period The engine speed is greater than zero rpm and the pattern from the timing ring is incorrect for five seconds. The engine speed is set to zero rpm.
The code is active.
The code is logged if the pattern from the timing ring returns for five seconds. The Electronic Control Module (ECM) provides the engine speed/timing sensor with 12 1.0 VDC. The engine speed/timing sensor provides a pulse signal to the ECM. The signal is created as the timing reference gear rotates past the pickup of the engine speed/timing sensor. The timing reference gear is mounted on the rear of the left camshaft. A unique tooth pattern on the timing reference gear allows the ECM to determine the crankshaft position, rotation, and rpm.The engine speed/timing sensor generates a pulse signal to the ECM as each tooth passes the sensor. The ECM counts the pulses in order to determine the engine rpm. The ECM memorizes the pattern of the pulses. 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 piston in 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 and will cause the ECM to stop the fuel injection.Note: If the engine timing gear is installed backward, the ECM will not fire the injectors and a 190-08 Engine Speed signal abnormal diagnostic code will be generated.
Illustration 1 g01208740
Left side view
(1) Engine speed/timing sensor
Illustration 2 g01524537
Schematic
Test Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Illustration 3 g01234146
Location of ECM connectors
Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors for the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g01524544
P1 ECM connector
(P1-51) Digital return
(P1-33) Engine speed/timing signal
(P1-40) Engine timing calibration -
(P1-41) Engine timing calibration +
(P1-43) +12 V supply
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. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion or 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 a "Logged" Diagnostic Code
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Check the diagnostic codes on Cat ET. Expected Result:Cat ET indicates that a 190-08 diagnostic code has recently been logged.Results:
OK - The 190-08 diagnostic code is logged. Proceed to Test Step 3.
Not OK - The 190-08 is not logged.Repair: The problem is no longer present. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect".STOPTest Step 3. Check the Supply Voltage to the Sensor
Disconnect the connector for the engine speed/timing sensor.
Turn the keyswitch to the ON position.
Measure the voltage between terminal A and terminal B at the sensor connector. Expected Result:The supply voltage is 12 1.0 VDC.Results:
OK - The supply voltage is 12 1.0 VDC. Proceed to Test Step 4.
Not OK - The supply voltage is not 12 1.0 VDC. Proceed to Test Step 6.Test Step 4. Check the Signal Voltage at the Sensor
Turn the keyswitch to the OFF position.
Remove the wire from terminal C of the sensor connector.
Turn the keyswitch to the ON position.
Measure the voltage between the sensor signal wire and terminal B of the sensor connector. Crank the engine and measure the voltage between the sensor signal wire and terminal B.
Turn the keyswitch to the OFF position.
Reconnect the signal wire. Expected Result:The voltage measures less than 3 VDC or more than 9 VDC when the keyswitch is in the ON position and the engine is not cranking. While the engine is cranking, the voltage is between 2.0 VDC and 7.0 VDC.Note: The voltage output is determined by the presence or the absence of a tooth on the timing gear.Results:
OK - The engine speed/timing sensor is producing the correct output signal. Proceed to Test Step 5.
Not OK - The engine speed/timing sensor is not producing the correct output signal.Repair: Replace the engine speed/timing sensor. Calibrate the sensor. Perform the calibration procedure Troubleshooting, "Timing - Calibrate".STOPTest Step 5. Check the Signal Voltage at the ECM
Turn the keyswitch to the OFF position.
Disconnect ECM connector J1/P1.
Remove the wire from ECM connector P1-33.
Reconnect ECM connector J1/P1.
Turn the keyswitch to the ON position.
Measure the signal voltage between the signal wire that was removed from terminal connector P1-33 and engine ground.
Crank the engine and measure the signal voltage between the signal wire that was removed from terminal connector P1-33 and engine ground.
Turn the keyswitch to the OFF position.
Replace all wires. Reconnect ECM connector J1/P1. Expected Result:The voltage measures less than 3 VDC or more than 9 VDC when the keyswitch is in the ON position and the engine is not cranking. While the engine is cranking, the voltage is between 2.0 VDC and 7.0 VDC.Note: The voltage signal is generated by the presence or the absence of a tooth on the timing gear.Results:
OK - A correct voltage appears at ECM connector P1 but the ECM is not reading the signal.Repair: