Table 2. Engine Troubleshooting with Codes for the 120M Motor Grader - Continued.
CDI FMI CODE
1779-05 Fuel Rail #1 Pres-
sure Valve Solenoid Current
A warning will display on instrument
panel. ECM will log diagnostic code.
Possible Performance Effect:
An electrical fault may prevent pres-
surized fuel to fuel rail, and may result
in loss of fuel injection. If solenoid for
fuel rail pump fails, it is likely that fuel
will not be pumped into fuel rail.
Engine will stall or engine will not
N OT E
The Engine ECM uses data from the fuel pressure sensor to control a
solenoid in the pump in order to maintain the desired fuel pressure in
the rail. Excess fuel returns to the fuel tank through a one-way return
valve. The fuel injection pump is not serviceable. Only personnel that
have had the correct training should adjust pump timing.
The fuel injection pump solenoid co trol circuit Y950-YL starts at engine
ECM harness connector EA-C1 terminal 25 and is routed to fuel rail
pump solenoid harness connector EA-C2 terminal 1. The solenoid
ground circuit starts at fuel rail pump solenoid harness connector EA-
C2 terminal 2 and is routed to the engine ECM harness connector EA-
C1 terminal 26.
Verify Diagnostic Code is Active.
N OT E
Always inspect the harness connectorsthat are involved in the circuit.
Poor connections can often be the cause of a problem in an electrical
circuit. Verify that all connections in the circuit are clean and secure,
and that all connections are in good condition. If a problem with a
connection is found, correct the problem and verify that this diagnostic
code is active before performing this procedure.
Perform open or short circuit test ateach harness connection to identify
correct harness to replace.
Perform this test only if condition is active.
1. Perform Fuel Rail Pump Solenoid 1779-05 Diagnostic Code Active -
Test (WP 0035) and check if diag- Proceed to Test Step 2.
nostic code 1779-05 becomes
Test Step 2. Test Solenoid Control
1. Turn the ignition switch to the