
104 KENR8601
Troubleshooting Section
g00530097
Illustration 62
System Schematic For The Engine Speed Se nsor
The EMCP II+P system monitors engine speed. The
EMCP II+P system uses engine speed in order to
accomplish many tasks. These tasks are included
in the following list.
•
Activating a shutdown for engine overspeed
•
Termin ating e ng ine crank ing
•
Determining the oil step speed
•
Causing the air shutoff solenoid to engage during
some fault shutdowns
The EMCP II+P does not control engine speed. The
engine speed sensor is mounted on the flywheel
housing of the engine.
The sensor creates a sine wave signal. The signal
is created from passing ring gear teeth. The rate of
the signal is one pulse per tooth. The sensor sends
the sine wave signal to the GSC+P. The frequency
of the signal is directly proportional to the speed of
the e ngine.
The GSC+P treats a CID 190 FMI 3 as a shutdown
fault. The engine is not allowed to crank or the
engine is not allowed to run when a CID 190 FMI 3
diagnostic code is active.
Note: The Engine Speed Sensor is commonly
referred to as magnetic pickup.
Note: Engines that are equipped with an electronic
governor have a separate speed sensor. The cable
of the speed sensor that is used by the G SC+P is
marked with one of the following numbers: 838-873,
838-973, and 973-938
This troubleshooting procedure is for a CID 190 FMI
3 that is active or inactive.
The possible causes of a CID 190 FMI 3 are listed
below.
•
There is an op e n in the signal circuit.
Clear the diagnostic code from the fault log after
troubleshooting is complete.
Test Step 1. CHECK THE HARNESS AND
THE SPEED SENSOR.
A. Turn the En gine Co nt rol Switch ( ECS) to
OFF/RESET.
B. Disconnect the harness connector from the
GSC+P.
C. At the GSC+P harness connector, measure the
resistance from pin “1” to pin “2”.
Expected Result:
The resistance should be from 100 to 350 ohms.
Results:
•
OK – There is probably an intermittent problem.
Proceed to Test Step 2.
•
NOT OK – The harness wiring or the speed sensor
has failed. Proceed to Test Step 2.
Test Step 2. CHECK FOR AN
INTERMITTENT FAULT.
A. Turn the ECS to OFF/RESET.
B. Turn the ECS to STOP.
C. Check the upper display for a CID 190 FMI 3.
Expected Result:
CID 190 FMI 3 should not appear on the upper
display.
Results:
•
OK – CID 190 FMI 3 does not appear on the
upper display. This step has corrected the problem.
STOP.
•
NOT OK – CID 190 FMI 3 appears on the upper
display. Proceed to Test S tep 3.
Test Step 3. CHEC K TH E RESISTANCE
OF THE ENGINE SPEED SENSOR.
A. Disco nnect the sensor from the engine harness.
The sensor remains fastened to the engine.