Dodge Ram Truck 1500-2500-3500. Manual — part 831
P0174-FUEL SYSTEM 2/1 LEAN (CONTINUED)
7.
ENGINE MECHANICAL
Turn the ignition off.
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from leaks.
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector
Are there any engine mechanical problems?
Yes
>> Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 11
8.
O2 SENSOR
Ignition on, engine not running.
Disconnect the 2/1 O2 Sensor harness connector.
With the scan tool, monitor the 2/1 O2 Sensor voltage.
O2 Sensor voltage should read 5.0 volts on the scan tool with the con-
nector disconnected.
Connect a jumper wire between the (K43) O2 Sensor 2/1 Signal circuit
and the (K902) O2 Return Upstream circuit in the O2 Sensor harness
connector.
NOTE: The voltage should drop from 5.0 volts to 2.5 volts with
the jumper wire in place.
Did the O2 Sensor voltage change from 5.0 volts to 2.5 volts
when the jumper wire was installed?
Yes
>> Replace the 2/1 O2 Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 9
NOTE: Remove the jumper wire before continuing.
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ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L
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P0174-FUEL SYSTEM 2/1 LEAN (CONTINUED)
9.
O2 SENSOR SIGNAL CIRCUIT
With the scan tool, monitor all the O2 Sensor voltage reading with the jumper wire removed.
NOTE: The scan tool will display all O2 Sensor voltage readings approximately 5.0 volts when only one O2
Sensor’s Signal circuit is shorted to voltage.
NOTE: The scan tool will display one O2 Sensor voltage close to zero and the others will read lower than
normal when one O2 Sensor Signal circuit contains excessive resistance.
Is the voltage above 4.8 volts?
Yes
>> Go To 10
No
>> Check all the O2 Signal circuits for a short to ground, open, or short to voltage. Inspect the O2 Sensor
connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module
per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
10.
(K902) O2 RETURN UPSTREAM CIRCUIT
Disconnect the 2/1 O2 Sensor harness connector.
Measure the voltage on the (K902) O2 Return Upstream circuit in the
O2 Sensor harness connector.
Is the voltage at 2.5 volts?
Yes
>> Go To 11
No
>> Check the (K902) O2 Return Upstream circuit for a short
to ground, open, or short to voltage. Inspect the O2 Sen-
sor connector and the PCM harness connector. If OK,
replace and program the Powertrain Control Module per
Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)
11.
PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Yes
>> Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
DR/DH
ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L
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P0174-FUEL SYSTEM 2/1 LEAN (CONTINUED)
12.
RESTRICTED FUEL SUPPLY LINE
WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or ser-
vicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow
these instructions can result in personal injury or death.
Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.
Install special 5/16 fuel line adapter tool #6539 between disconnected fuel line and the fuel pump module.
Attach a fuel pressure test gauge to the T fitting on tool #6539.
Ignition on, engine not running.
With the scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge.
NOTE: Fuel pressure specification is 407 KPa +/- 34 KPa (59 psi +/- 5 psi).
CAUTION: Stop All Actuations.
Is the fuel pressure within specification?
Yes
>> Repair or replace fuel supply line as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 13
13.
FUEL PUMP INLET STRAINER
Turn the ignition off.
WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or ser-
vicing any fuel system hose, fitting or line, the fuel system pressure must be released.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?
Yes
>> Replace the Fuel Pump Inlet Strainer.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 14
14.
FUEL PUMP MODULE
If there are no possible causes remaining, view repair.
Repair
Replace the Fuel Pump Module.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L
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P0175-FUEL SYSTEM 2/1 RICH
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ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L
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