
RENR9348-01 135
Troubleshooting Section
B. Restore electrical power to the ECM.
C. Monitor the active diagnostic code screen on Cat
ET. Look for an active diagnostic code for an
engine pressu
re sensor.
Note: Wait at least 30 seconds so that any codes
may become act
ive.
D. Determine if the problem is related to an open
circuit diagn
ostic code (03) or a short circuit
diagnostic code (04).
Expected Res
ult:
No diagnostic codes are active.
Results:
•
OK – No diagnos
tic codes are active for the engine
pressure sensors.
Repair: The p
roblem seems to be resolved.
The problem may have been related to a faulty
connection in the harness. Carefully reinspect the
connectors
and wiring. Refer to Troubleshooting,
“Electrical Connectors - Inspect”.
STOP.
•
Not OK – A 03 diagnostic code is active at
this time. T
he ECM is detecting an open circuit
condition. Proceed to Test Step 5.
•
Not OK – A 04 d
iagnostic code is active at this
time. The ECM is detecting a short circuit condition.
Proceed to Test Step 4.
Test Step 4. Disconnect the Suspect
SensorinOrdertoCreateanOpenCircuit
A. Remove ele
ctrical power from the ECM.
B. Disconnect the sensor connector of the sensor
with the sh
ort circuit diagnostic code (04).
C. Restore electrical power to the ECM.
D. Access the “Active Diagnostic Code” screen on
Cat ET. Check for an active open circuit diagnostic
code (03)
while the sensor is disconnected.
Note: Wait at least 30 seconds for activation of the
diagnost
ic codes.
E. Remove electrical power from the ECM.
Expected Result:
A 03 diagn
ostic code became active after the sensor
was disconnected.
Results:
•
OK – A 04 diagnostic code was active before the
sensor was disconnected. A 03 diagnostic code
became active
after the sensor was disconnected.
Repair: There may be a problem with a sensor.
Temporarily c
onnect a new sensor to the harness,
but do not install the new sensor in the engine.
Verify that there are no active diagnostic codes for
the sensor. I
f there are no active diagnostic codes
for the sensor, permanently install the new sensor.
Clear any logged diagnostic codes.
STOP.
•
Not OK – When t
he sensor is disconnected, a 04
diagnostic code remains active for the suspect
sensor. There is a problem in the circuit between
the sensor h
arness connector and the ECM. The
problem may be in the ECM. Leave the sensor
disconnected. Proceed to Test Step 6.
Test Step 5. Create a Short at the Suspect
Sensor Connector
A. Remove ele
ctrical power from the ECM.
B. Fabricate a jumper wire that is long enough to
short the t
erminals at the sensor connector. Crimp
connector sockets to each end of the jumper wire.
C. Install th
e jumper wire between terminal B (sensor
return) and terminal C (sensor signal) on the
harness side of the suspect sensor’s connector.
D. Restore electrical power to the ECM.
E. Monitor t
he “Active Diagnostic Codes” screen on
Cat ET. Check for an active short circuit diagnostic
code (04) while the jumper wire is installed.
Note: Wait at least 30 seconds for activation of the
diagnostic code.
F. Remove electrical power from the ECM.
G. Remove th
e jumper wire.
Expected Result:
A 04 diagnostic code was active when the jumper
wire was installed.
Results:
•
OK – A 04 di
agnostic code was active when the
jumper wire was installed.