825046 Mercury SCREW

Table 1
Diagnostic Codes Table    
Description    Conditions which Generate this Code    System Response    
91-8 Throttle Position Sensor abnormal frequency, pulse width, or period     The Engine Electronic Control Module (ECM) detects a sensor frequency that is less than 150 Hz or a sensor frequency that is greater than 1000 Hz for two seconds.
OR
The engine ECM detects a duty cycle that is less than 5 percent or a duty cycle that is greater than 95 percent for one second.
The ECM has been powered for three seconds.
    The code will be active.
The throttle signal defaults to a zero percent duty cycle.    
1249-8 Secondary Throttle Position signal abnormal    
1923-8 Remote Throttle Position Sensor abnormal frequency, pulse width, or period    Marine propulsion engines have two modes of operation for speed control. Each mode has a set of three governor gain factors that can be adjusted.
The default mode is a variable speed control that is used for propulsion.
A constant speed control can be selected by grounding an input to the engine's electronic control module. This mode is used with an electronic propulsion system during occasions when it is necessary for the vessel to maintain a fixed position.Some parameters must be programmed in order for the mode for the constant speed control to operate:
The "Engine Governor Desired Constant Speed" is programmed with the desired rpm.
The Governor Gain Factor 2 ("Prop Gain 2") is validated or adjusted.
The Governor Minimum Stability Factor 2 ("Prop Int Min 2") is validated or adjusted.
The Governor Maximum Stability Factor 2 ("Prop Int Max 2") is validated or adjusted.The factors for the governor gain are programmed at the factory in order to provide good performance. However, these factors are validated during the commissioning procedure. The factors are adjusted, if necessary.The engine ECM has three different inputs for a throttle signal. The three throttle inputs to the ECM are listed below:
"Local Throttle"
"Remote Throttle"
"Global Throttle"The signal for the "Local Throttle" and the "Global Throttle" is a PWM signal. The ECM can be configured in order to accept the signal for the "Remote Throttle" as either a PWM signal or a 4-20mA current signal.The ECM monitors the following switches in order to determine the correct throttle signal to use:
"Global Throttle Select Switch"
"Local/Remote Select Switch"The ECM must use a variable speed map or a constant speed map for the governor gain. The "Dual Dyamic Select Switch" is used to make that selection. If the "Dual Dyamic Select Switch" is open the variable speed map will be used. If the "Dual Dyamic Select Switch" is closed the constant speed map will be used. The following Illustration 1 gives the various switch positions that determine the correct throttle signal to use:
Illustration 1 g01401409
The duty cycle of the PWM signal must be between 5 percent and 95 percent for a valid signal. The frequency of the PWM signal must be a frequency between 150 Hz and 1000 Hz. The ECM converts the throttle signal into a usable throttle position. The ECM displays the throttle position as a percentage between 0 and 100 percent.The 4 to 20 mA current signal is provided by the customer. The current signal is isolated through a pair of isolation transformers that are mounted in the user interface panel.
Illustration 2 g01400977
Typical schematic "MMSII"
Illustration 3 g01400979
Typical schematic for a "Retrofit" or "ECP" panel
Illustration 4 g01400980
P1 ECM connector (P1-10) Remote PWM (P1-11) Global PWM (P1-20) "Local/Remote Switch" (P1-22) "Global Throttle Select Switch" (P1-28) "Dual Dynamic Select Switch" (P1-36) Remote 4-20 mA + (P1-37) Remote 4-20 mA -
Illustration 5 g01249301
P2 ECM connector (P2-68) Local PWM
Illustration 6 g01400983
Connector for the user interface panelA-C2/KJ-C2 and AC-C2/KJ-C2 connector (Terminal 9) Global PWM (Terminal 13) Remote 4-20 mA + (Terminal 14) Local PWM (Terminal 15) Remote PWM (Terminal 20) "Local/Remote Switch" (Terminal 23) Remote 4-20 mA - (Terminal 33) "Global Throttle Select Switch" (Terminal 34) "Dual Dynamic Select Switch"
Illustration 7 g01404714
Customer ConnectorAC-C1 connector (Terminal 10) Remote PWM (Terminal 29) Global PWM (Terminal 31) "Local/Remote Switch" (Terminal 33) Potentiometer (Terminal 34) Potentiometer (Terminal 35) Potentiometer (Terminal 37) "Global Throttle Select Switch" (Terminal 38) "Dual Dynamic Select Switch" (Terminal 39) Remote 4-20 mA - (Terminal 40) Remote 4-20 mA +
Illustration 8 g01234146
Location of ECM connectorsTest Step 1. Check the Throttle Position with Caterpillar Electronic Technician (ET)
Connect Cat ET to the service tool connector. Start Cat ET.
Turn the local/remote switch on the control panel to the LOCAL position.
Observe the throttle position on Cat ET.
Adjust the