KENR9126 173
Troubleshooting Section
Test Step 5. Check the Sensor's
Resistance at the E CM
A. Disconnect the J2/P2 connectors.
Note: Be sure t
o wiggle the harness during the
following measurement in order to reveal an
intermittent condition.
B. Measure the resistance between P2-41 (fuel level
sensor) and P2-45 (sensor return) at the ECM
connector.
Expected Result:
The resistance measurement is approximately equal
to the resistance that was measured at the sensor
connector
.
Results:
•
OK – The resistance measurement is
approximately equal to the resistance
measurem
ent that w as recorded in the previous
Test Step.
Repair:
The fuel level sensor and the wiring are
OK. Perform the following procedure:
1. Connect
the J2/P2 connectors.
2. Restore the electrical power to the ECM. Check
for a di
agnostic code for the fuel level sensor
again. Wait at least 30 seconds in order for
codes to become active.
a. If the diagnostic code does not recur, the
problem is resolved. The original problem
was pr
obably caused by a poor electrical
connection. Return the engine to service.
STOP.
b. If the diagnostic code recurs, Replace the
ECM. Refer to electronic troubleshooting
Trou
bleshooting, “Replacing the ECM”.
Verify that the problem is resolved.
STO
P.
•
Not OK – The resistance measurement is not
app
roximately equal to the resistance that was
measured at the sensor connector. There is a
problem with the engine's wiring harness. There
ma
y be a problem with a connector.
Repair: Repair the wiring, when possible. Replace
pa
rts, if necessary. Verify that the problem is
resolved.
S
TOP.
i03460681
Fuel Rai l Pump So leno id - Test
System Operation Description:
Use this procedure to troubleshoot the system when
one of the following diagnostic codes is active or
easily repea
ted:
•
1779-05 Fuel Rail #1 Pressure Valve Solenoid
current bel
ow normal
•
1779-06 Fuel Rail #1 Pressure Valve Solenoid
current ab
ove normal
Note: The fuel rail pump is installed on the engine at
the factor
y. The fuel rail pump is not serviceable part.
The fuel rail pump solenoid is used to control the
output fr
om the fuel rail pump. The solenoid receives
an electrical supply from the Electronic Control
Module (ECM). The fuel rail pump solenoid is then
energize
d when the fuel is required to be pumped
into the fuel rail. Varying the timing of the voltage to
the solenoid controls the fuel delivery from the fuel
rail pum
p.
When the fuel rail pump solenoid is deactivated, the
fuel tha
t is not sent to the fuel rail is returned to the
fuel tank.
The fue
l rail pump solenoid forms part of the closed
loop control system for the fuel rail pressure in
conjunction with the fuel rail pressure sensor, ECM
and th
e software. The fuel rail pressure sensor
measures the fuel pressure in the high pressure fuel
rail. The signal from the fuel rail pressure sensor is
proce
ssed by the ECM and software. The measured
pressure is compared to the desired fuel rail pressure
for the given engine operating conditions.
If the fuel rail pump solenoid fails, it is likely that the
fuel will not be pumped into the high pressure fuel rail
and e
ngine shutdown or failure to start the engine is
expected. Fuel rail pressure can be observed on the
status screen of the electronic service tool.
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