Dodge Ram Truck 1500-2500-3500. Manual — part 1180

P0171-FUEL SYSTEM 1/1 LEAN (CONTINUED)

9.

TP SENSOR SWEEP

With the scan tool, read the TP Sensor voltage.

While monitoring the scan tool, slowly open and close the throttle.

Does the voltage increase and decrease smoothly?

Yes

>> Go To 10

No

>> Replace the Throttle Position Sensor.

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

10.

MAP SENSOR OPERATION

Turn the ignition off.

Connect a Vacuum Gauge to a Manifold Vacuum source.

Start the engine.

Allow the engine to idle.

NOTE: If engine will not idle, maintain a constant RPM above idle.
With the scan tool in Sensors, read the MAP Sensor vacuum value.

NOTE: Remove the vacuum gauge before continuing.

Is the scan toolreading within 1

(

of the Vacuum Gauge reading?

Yes

>> Go To 11

No

>> Replace the MAP Sensor.

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

11.

ECT SENSOR OPERATION

NOTE: For this test to be valid, the thermostat must be operating correctly.

NOTE: This test works best if performed on a cold engine (cold soak)
Ignition on, engine not running.

With the scan tool, read the Engine Coolant Temperature Sensor value. If the engine was allowed to sit overnight
(cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.

NOTE: If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is
reached.
Start the Engine.

During engine warm-up, monitor the Engine Coolant Temperature value. The temp value change should be a
smooth transition from start up to normal operating temp 82°C (180°F). The value should reach at least 82°C
(180°F).

Did the Engine Coolant Temperature increase smoothly and did it reach at least 82°C (180°F)?

Yes

>> Go To 12

No

>> Replace the Engine Coolant Temperature Sensor.

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

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P0171-FUEL SYSTEM 1/1 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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P0171-FUEL SYSTEM 1/1 LEAN (CONTINUED)

14.

(K41) O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.

Disconnect the PCM harness connectors.

Measure the resistance between ground and the (K41) O2 Sensor 1/1
Signal circuit at the PCM harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the (K41) O2 Sensor 1/1 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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P0172-FUEL SYSTEM 1/1 RICH

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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