Dodge Ram Truck 1500-2500-3500. Manual — part 1184

P0174-FUEL SYSTEM 2/1 LEAN (CONTINUED)

12.

ENGINE MECHANICAL PROBLEM

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

>> Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

13.

O2 SENSOR

NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test.
Ignition on, engine not running.

Disconnect the harness connector(s) of the O2 Sensor(s) that had a voltage reading below 4.5 volts in the previous
step.

With the scan tool, monitor the O2 Sensor voltage reading(s).

Is the voltage above 4.5 volts for any of the O2 Sensors?

Yes

>> Replace the O2 Sensor that had a voltage reading above 4.5 volts.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 14

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0174-FUEL SYSTEM 2/1 LEAN (CONTINUED)

14.

(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.

Disconnect the PCM harness connectors.

Measure the resistance between ground and the (K43) O2 Sensor 2/1
Signal circuit at the PCM harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the (K43) O2 Sensor 2/1 Sig-

nal circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer
to 9 - ENGINE - STANDARD PROCEDURE)

No

>> Go To 15

15.

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.

If there are no possible causes remaining, view repair.

Repair

Replace and program the Powertrain Control Module per Service Information.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0175-FUEL SYSTEM 2/1 RICH

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0175-FUEL SYSTEM 2/1 RICH (CONTINUED)

For the Engine circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

The fuel feedback system will maintain a stoiciometric fuel/air mixture, 14.7:1, by modifying the injector pulsewidth
according to the oxygen content of the exhaust gas. The PCM makes short term and long term fuel corrections to
maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. Short term fuel correction is based on
upstream O2 sensor output and is designed for quick engine response. The long term fuel correction compensated
for variations in the engine specifications, sensor tolerances and component aging and is designed to correct rich
and lean conditions over a longer period of time.

•

When Monitored:
With the engine running in closed loop mode, the ambient/battery temperature above 20 deg. F and altitude
below 8500 ft.

•

Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a purge fuel multiplier and the result
is below a certain value for 30 seconds over two trips, a freeze frame is stored, the MIL illuminates and a
trouble code is stored. Two Trip Fault. Three good trips to turn off the MIL.

Possible Causes

O2 SENSOR

(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT OPEN

(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT SHORTED TO VOLTAGE

2/1 O2 SENSOR HEATER OPERATION

EVAP SYSTEM OPERATION

TP SENSOR VOLTAGE GREATER THAN 0.92 OF A VOLT WITH THROTTLE CLOSED

TP SENSOR

FUEL FILTER/PRESSURE REGULATOR

MAP SENSOR

ECT SENSOR

ENGINE MECHANICAL CONDITION

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).

Diagnostic Test

1.

GOOD TRIP EQUAL TO ZERO

NOTE: Check for contaminates that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.

With the scan tool, read DTCs and record the related Freeze Frame data.

NOTE: Any O2 Sensor, TPS, ECT, MAP, or EVAP DTCs must be repaired before continuing.

Is the Good Trip Counter displayed and equal to zero?

Yes

>> Go To 2

No

>> Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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