17643 1 Mercury ROD SNAP

Illustration 1 g00479965
System Schematic For Starting Motor Relay (SMR)
Illustration 2 g00479969
System Schematic For Electronic Governor Relay
Illustration 3 g00479971
System Schematic For Air Shutdown Relay (ASR)To find the cause of an overcrank shutdown, perform this procedure.
Initial Check Before you proceed with the troubleshooting procedures, perform the following preliminary checks.
Check for active diagnostic codes and other flashing indicators on the GSC+. The only exception is the CID 566 FM 7. If the fault is present, then correct the fault first. Go to the appropriate procedure for that fault.
Check the fuel level and quality. Refer to the Engine Service Manual.
Check for a plugged fuel filter. Refer to the Engine Service Manual.
Check for a plugged air filter. Refer to the Engine Service Manual.
Check the air shutoff solenoid (if equipped) for activation. The solenoid must be deactivated in order for the engine to start. See Testing And Adjusting, "Troubleshooting Diagnostic Codes".
Check fuse "F2" and "F4" on the relay module. If either fuse is blown, proceed to 10.
Check the engine starting system and the fuel system. (To check the fuel control solenoid, see Testing And Adjusting, "Troubleshooting Diagnostic Codes".) If there is a fault, refer to the Engine Service Manual. If there is no engine fault or fuel system fault, proceed to 2.
Check setpoints.This step checks setpoints P17 (total cycle crank time) and P18 (cycle crank time).
Note setpoints P17 and P18. See Systems Operation, "Engine/Generator Setpoint Viewing OP2".
Compare the setpoints that are viewed with the specified setpoints. The default value for a P17 is 90 seconds. The default value for a P18 is 10 seconds.Expected Result: The setpoint value that is viewed and the specified setpoint value should agree.Results:
OK: Proceed to Step 3.
NOT OK: The setpoints do not agree. Reprogram setpoints P17 and P18. See Systems Operation, "Engine/Generator Programming OP5". STOP.
Check the battery voltage.
Make sure that the engine is off. Measure the system voltage at the batteries.Expected Result:For 24 volt systems, the voltage should be from 24.8 to 29.5 DCV.For 32 volt systems, the voltage should be from 33.1 to 39.3 DCV.Results:
OK: Proceed to Step 3.
NOT OK: Further checking of the battery system is necessary. See Testing And Adjusting, "Troubleshooting Diagnostic Codes". STOP.
Check the engine starting function. Steps 4 through 9 require voltage measurements to be made during simulated engine cranking. The starting motor is disabled.Note: The GSC+ is attempting to crank whenever the K4 indicator is ON. The K4 indicator is on the lower display. Be aware of the 10 second crank cycle that is factory set. Ensure that the K4 indicator is ON while you are making the following measurements. An assistant should observe the GSC+, if necessary. More than one start may be required to complete this test.
Disconnect the pinion solenoid wire of the starting motor. The pinion solenoid wire remains disconnected for all of the remaining steps of this procedure.
Prepare to measure the DC voltage from the disconnected "B+" pinion solenoid wire to "B-" (ground).
Turn the ECS to the OFF/RESET position and then turn the ECS to the START position.
Measure the voltage.Expected Result: The voltage that is measured voltage should equal the system voltage ( 2.0 DCV). The system voltage is