Dodge Ram Truck 1500-2500-3500. Manual — part 1066
P0251-CP3 PUMP REGULATOR CONTROL (CONTINUED)
For the Engine circuit diagram (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CON-
TROL MODULE - SCHEMATIC - ELECTRICAL)
For a complete wiring diagram Refer to Section 8W.
•
When Monitored:
When the ignition is on.
•
Set Condition:
The ECM detects a discrepancy between the PWM supplied to the Electronic Fuel Control Actuator and the
PWM returned from the Electronic Fuel Control Actuator.
Possible Causes
FUEL PUMP
(K181) FUEL CONTROL ACTUATOR DRIVER OPEN
(K31) RETURN CIRCUIT OPEN FROM FCA TO ECM
(K181) FUEL CONTROL ACTUATOR DRIVER CIRCUIT SHORTED TO EXTERNAL VOLTAGE
(K31) FUEL CONTROL ACTUATOR RETURN CIRCUIT SHORTED TO EXTERNAL VOLTAGE
(K31) FCA RETURN CIRCUIT SHORTED TO (K181) FCA DRIVER CIRCUIT
(K181) FUEL CONTROL ACTUATOR DRIVER CIRCUIT SHORTED TO GROUND
(K181) FUEL CONTROL ACTUATOR DRIVER CIRCUIT SHORTED TO ANOTHER CIRCUIT
(K31) FUEL CONTROL ACTUATOR RETURN CIRCUIT SHORTED TO ANOTHER CIRCUIT
INTERMITTENT CONDITION
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.
FUEL PUMP
Ignition on, engine not running.
Disconnect the Fuel Control Actuator (FCA) harness connector.
Connect an incandescent test light across the Fuel Control Actuator
driver circuit and the Fuel Control Actuator return circuit at the fuel
control actuator harness connector.
Observe the test light.
The ECM will perform a self test of the circuit which should momen-
tarily flash the test light brightly, one time, approximately 20 seconds
after being connected.
NOTE: Check connectors - Clean/repair as necessary.
NOTE: Compare test light brightness to that of a direct connec-
tion to the battery.
Did the light flash brightly?
Yes
>> Replace the Fuel Pump.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MOD-
ULE - DIAGNOSIS AND TESTING)
No
>> Go To 2
9 - 1186
ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL
DR/DH
P0251-CP3 PUMP REGULATOR CONTROL (CONTINUED)
2.
(K181) FUEL CONTROL ACTUATOR DRIVER OPEN
Turn the ignition off.
Disconnect the ECM harness connectors.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the FCA driver circuit between the elec-
tronic fuel control actuator harness connector and the ECM harness
connector.
Is the resistance less than 10 Ohms?
Yes
>> Go To 3
No
>> Repair the (K181) Fuel Control Actuator Driver circuit
OPEN.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
3.
(K31) RETURN CIRCUIT OPEN
Measure the resistance of the (K31) return circuit between the FCA
harness connector and the ECM harness connector.
Is the resistance less than 10 Ohms?
Yes
>> Go To 4
No
>> Repair or replace the engine wiring harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
DR/DH
ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL
9 - 1187
P0251-CP3 PUMP REGULATOR CONTROL (CONTINUED)
4.
(K181) FUEL CONTROL ACTUATOR DRIVER CIRCUIT SHORTED TO EXTERNAL VOLTAGE
Measure the voltage between the (K181) FCA driver circuit in the FCA
harness connector and battery negative.
Is the voltage greater than 1 volts?
Yes
>> Repair the (K181) FCA driver circuit shorted to external
voltage.
No
>> Go To 5
5.
(K31) FUEL CONTROL ACTUATOR RETURN CIRCUIT SHORTED TO EXTERNAL VOLTAGE
Measure the voltage between the (K31) FCA return circuit in the FCA
harness connector and battery negative.
Is the voltage greater than 1 volts?
Yes
>> Repair the (K31) FCA return circuit shorted to external
voltage.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No
>> Go To 6
9 - 1188
ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL
DR/DH
P0251-CP3 PUMP REGULATOR CONTROL (CONTINUED)
6.
(K31) FCA RETURN CIRCUIT SHORTED TO (K181) FCA DRIVER CIRCUIT
Measure the Resistance between the return circuit in the FCA harness
connector and Driver circuit.
Is the resistance less than 10 Ohms?
Yes
>> Repair the (K31) FCA Return circuit shorted to (K181)
FCA Driver circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No
>> Go To 7
7.
(K181) FUEL CONTROL ACTUATOR DRIVER CIRCUIT SHORTED TO GROUND
Measure the resistance between the (K181) FCA driver circuit in the
FCA harness connector and battery negative.
Is the resistance less than 10 Ohms?
Yes
>> Repair the (K181) FCA driver circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No
>> Go To 8
DR/DH
ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL
9 - 1189
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