ENGINE CONTROL MOTOR (EC MOTOR)
JT07065 Test Harness
The purpose of test is to check continuity of EC motor
wiring harness (F) and there is a signal from engine and
pump controller (EPC).
NOTE: The laptop computer with excavator diagnostics
program can be used to check the electrical signal
from the engine and pump controller to the engine
control motor. Select "15 EC motor position" from
Monitor Data Items. Typical readings are
110--114 steps at slow idle to 390--410 steps at
fast idle. The readings can vary from machine to
machine. What to look for is that the readings
change when the engine rpm dial is turned, and
when the E mode, HP mode, or auto-idle mode is
IMPORTANT: Turn key switch off before
disconnecting any electrical
connectors. Disconnecting electrical
connectors while engine is running or
D--Engine Control Motor
with key switch on can damage engine
E--Engine Control Sensor Wiring Harness
and pump controller or other electrical
F--Engine Control Motor Wiring Harness
1. Stop engine. Turn key switch to OFF.
IMPORTANT: Retainer tab on male half of wiring
harness connector halves must be
pushed down before pulling halves
apart. Never pull on wiring leads.
2. Push retainer tab down then pull connector halves
3. Install test harness in series with the engine control
motor wiring harness (F).
4. Turn key switch to ON.
5. While observing test indicator lights,
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