Dodge Ram Truck 1500-2500-3500. Manual — part 1185

P0175-FUEL SYSTEM 2/1 RICH (CONTINUED)

2.

CHECKING FUEL PRESSURE

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.
Install a fuel pressure gauge.

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 379 KPa +/- 14 KPa (55 psi +/- 2 psi).

Choose a conclusion that best matches your fuel pressure reading.

Within Specification

Go To 3

Above Specification

Replace the fuel filter/pressure regulator.

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

CAUTION: Stop All Actuations.

3.

O2 SENSOR OPERATION

Ignition on, engine not running.

With the scan tool, monitor all of the O2 Sensor voltage readings.

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

Yes

>> Go To 4

No

>> Go To 11

4.

O2 SENSOR HEATER OPERATION

Turn the ignition off.

NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow
the O2 Sensor voltage to stabilize between 4 and 5 volts.
Ignition on, engine not running.

With the scan tool, actuate the O2 Heater Test.

With the scan tool, monitor O2 Sensor voltage for at least 2 minutes.

Does the voltage stay above 4.5 volts?

Yes

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

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

No

>> Go To 5

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P0175-FUEL SYSTEM 2/1 RICH (CONTINUED)

5.

EVAP SYSTEM OPERATION

NOTE: The engine must be at operating temperature and in closed loop to perform this test.
Start the engine.

WARNING: When the engine is operating, do not stand in a direct line with the fan. Do not put your hands
near the pulleys, belts, or fan. Do not wear loose clothing.
Allow the engine to reach normal operating temperature.

With the scan tool select System Tests, perform the Purge Vapors Test.

Observe the Short Term Adaptive value and press 3 to flow.

NOTE: Short Term Adaptive value change.

Did the Short Term Adaptive value change?

Yes

>> Go To 6

No

>> Refer to the Driveability category and perform the appropriate Diagnostic test.

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

6.

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

Ignition on, engine not running.

With the scan tool, read TP Sensor voltage.

NOTE: The throttle must be against the stop.

Is the voltage 0.92 of a volt or less with the Throttle closed?

Yes

>> Go To 7

No

>> Check for a binding throttle condition. If OK, replace the Throttle Position Sensor.

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

7.

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 8

No

>> Replace the Throttle Position Sensor.

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

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P0175-FUEL SYSTEM 2/1 RICH (CONTINUED)

8.

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.

Is the scan tool reading within 1

(

of the Vacuum Gauge reading?

Yes

>> Go To 9

No

>> Replace the MAP Sensor.

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

NOTE: Remove the vacuum gauge before continuing.

9.

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 value increase smoothly and reach at least 82°C?

Yes

>> Go To 10

No

>> Replace the Engine Coolant Temperature Sensor.

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

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P0175-FUEL SYSTEM 2/1 RICH (CONTINUED)

10.

ENGINE MECHANICAL PROBLEM

Check for any of the following conditions/mechanical problems.

AIR INDUCTION SYSTEM - must be free from restrictions.

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 Diagnostic Procedure.

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

11.

O2 SENSOR

Disconnect the sensor harness connector of the O2 Sensor(s) that had a voltage value greater than 4.5 volts in the
previous step.

Ignition on, engine not running.

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

Is the O2 Sensor voltage above 4.5 volts?

Yes

>> Replace the O2 Sensor.

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

No

>> Go To 12

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