Illustration 1 g03319752
Schematic for the active sensors
Troubleshooting Test Steps Values Results
1. Check for Diagnostic CodesA. Establish Diagnostic Result: A -3 diagnostic code is
communication between Caterpillar Electronic code active.Proceed to Test Step 2.
Technician (ET) and the ECM . Refer to
Result: A -4 diagnostic code is active.
Troubleshooting, “Electronic Service Tools”, if
necessary. Proceed to Test Step 3.
B. Turn the keyswitch to the ON position. Result: A 2458-2 or a 3251-2 diagnostic
code is active.
C. Look for “-3″, or ” -4″ active or logged codes.
Proceed to Test Step 6.
2. Create a Short at the Sensor ConnectorA. Use a Short Result: A -4 diagnostic code became
test lamp in order to create a short between terminal created active after creating the short at the
3 (signal) and terminal 2 (sensor return) at the sensor sensor connector.The wiring is OK.
connector. Replace the sensor.
Verify that the problem is resolved.
B. Turn the keyswitch to the ON position.
Result: A -4 diagnostic code does not
C. Monitor the diagnostic codes on Cat ET. Check for
become active for the suspect sensor.
an active -4 diagnostic code for the suspect sensor.
Proceed to Test Step 4.
D. Turn the keyswitch to the OFF position.
3. Create an Open at the Suspect Sensor Create an Result: A -3 diagnostic code became
ConnectorA. Turn the keyswitch to the OFF position. Open active after disconnecting the sensor.The
wiring is OK. Replace the sensor.
B. Disconnect the sensor connector of the suspect
Verify that the problem is resolved.
sensor with the active -4 diagnostic code.
Result: A -3 diagnostic code did not
C. Turn the keyswitch to the ON position.
became active after disconnecting the
D. Monitor the diagnostic codes on Cat ET. Check for sensor.
an active -3 diagnostic code for the suspect sensor.
Proceed to Test Step 4.
E. Turn the keyswitch to the OFF position.
4. Check the 5 VDC Supply Voltage at the Sensor Test Result: The supply voltage is
ConnectorA. Turn the keyswitch to the ON position. passed approximately 5.0 ± 0.2 VDCConnect the
sensor and then proceed to Test Step 5
B. Measure the voltage between pin 1 and pin 2 at
the suspect sensor. Result: The supply voltage is not
approximately 5.0 ± 0.2 VDC.
There is a short in the harness to the
battery. Repair the wiring or replace the
harness
Verify that the problem is resolved.
STOP
5. Perform the Wiggle Test Test Result: The wiring failed the Wiggle
passed Test.There is a problem with the wiring.
Carefully following this procedure is the best way to
Repair the wiring or replace the wiring.
identify the root cause of an intermittent problem.
Verify that the problem is resolved.
A. Turn the keyswitch to the ON position. STOP
B. Use CAT ET to run the “Wiggle Test”. Result: The wiring passed the Wiggle
Test.
C. Slowly wiggle the wiring and the connectors
between the P2 connector and the sensor. Pay The problem may be intermittent. Inspect
particular attention to the wiring near each the wiring. Refer to Troubleshooting,
connector. Be sure to wiggle all of the wiring. “Electrical Connectors – Inspect”.
As you wiggle the wiring look for these problems. If the wiring looks OK perform the
1. Loose connectors or damaged connectors following procedure.
2. Moisture on the connectors or the wiring 1. Turn the keyswitch to the OFF position.
3. Damaged that is caused by excessive heat 2. Disconnect the connectors. Carefully
4. Damage that is caused by chafing inspect the terminals for proper
5. Improper routing of wiring installation. Make sure that each terminal
6. Damaged insulation is clean and dry.
3. Insert a pin into each socket. Verify
that each socket grips the pin firmly.
Repair any problems.
4. Connect all connectors.
5. Verify that the problem is resolved.
6. Return the unit to service.
STOP
Table 2
Illustration 2
(1) Differential pressure lines
6. Inspect the DPF Differential Pressure Lines, Fittings, Result: The DPF differential pressure
and Manifold lines, fittings, and manifold are
Lines
connected and free from obstructions.
A. Ensure that the DPF differential pressure lines are inspected
connected. Proceed to Test Step 7
B. Ensure that the DPF differential pressure lines, Result: The DPF differential pressure
fittings, and manifold are free from obstructions. Make lines are not connected or the lines,
sure that moisture has not frozen in the lines, fittings, fittings, and manifold have
and manifold. obstructions.
Note: The 2458-2 or the 3251-2 code will not activate Repair or replace the DPF differential
for several hours if the ambient temperature is below pressure line. Clear all codes. Return
7° C (45° F) or if an active regeneration has not been the engine to service.
performed. If troubleshooting a 2458-2 or a 3251-2
code and ambient temperature is below
7° C (45° F), perform a “Manual DPF regeneration”
after completing the repair to verify that the problem
has been resolved.
7. Inspect the Electrical Connectors for the ARD Pilot Connectors Result: A 2458-2 or a 3251-2 diagnostic
Fuel Pressure Sensor and the DPF Differential inspected code will appear when the connectors
Pressure Sensor are switched between sensors, be
certain the connectors are connected
A. Check the connectors for the differential pressure
to the correct sensors.
sensor and the pilot fuel pressure sensor to ensure
Connect the connectors to the correct
that the connectors are connected to the proper
sensors. Verify that the problem is
sensor.
resolved. Clear all codes. Return the
Note: The 2458-2 or the 3251-2 code will not activate engine to service.
for several hours if the ambient temperature is below
7° C (45° F) or if an active regeneration has not been
performed. If troubleshooting a 2458-2 or a 3251-2
code and ambient temperature is below
7° C (45° F), perform a “Manual DPF regeneration”
after completing the repair to verify that the problem
has been resolved.
Table 3
Test Step 1.
Complete the procedure in the order in which the steps are listed.
Results:
• The procedure corrected the issue. – STOP
• The procedure did not correct the issue. –Repair: Contact your Cat dealer Technical Communicator
(TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).
STOP
