Dodge Ram Truck 1500-2500-3500. Manual — part 829

P0172-FUEL SYSTEM 1/1 RICH (CONTINUED)

5.

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 a scan tool, read the MAP Sensor vacuum value.

Is the scan tool reading within 1

(

of the Vacuum Gauge reading?

Yes

>> Go To 6

No

>> Replace the MAP Sensor.

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

NOTE: Remove the vacuum gauge before continuing.

6.

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 a 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 ECT value increase smoothly and reach at least 180°F (82°C)?

Yes

>> Go To 7

No

>> Replace the Engine Coolant Temperature Sensor.

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

7.

EVAP PURGE SOLENOID OPERATION

Turn the ignition off.

Disconnect the hoses at the Evap Purge Solenoid.

Using a hand vacuum pump, apply 10 inches of vacuum to the Evap Purge Solenoid vacuum source port on the
component side.

Did the Evap Purge Solenoid hold vacuum?

Yes

>> Go To 8

No

>> Replace the EVAP Purge Solenoid.

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

NOTE: Connect the vacuum hoses before continuing.

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ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L

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P0172-FUEL SYSTEM 1/1 RICH (CONTINUED)

8.

ENGINE MECHANICAL

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

>> Go To 12

9.

1/1 O2 SENSOR

NOTE: Perform the following test on the O2 Sensors whose volt-
age was not switching properly in the previous step.
Ignition on, engine not running.

Disconnect the 1/1 O2 Sensor harness connector.

With a scan tool, monitor the 1/1 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 (K41) O2 Sensor 1/1 Signal circuit
and the (K902) O2 Return Upstream circuit in the O2 Sensor harness
connector.

NOTE: The voltage should drop from 5.0 volts down to 2.5 volts
with the jumper wire connected.

Did the O2 Sensor voltage drop from 5 volts to 2.5 volts when
the jumper wire was installed?

Yes

>> Replace the 1/1 O2 Sensor

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

No

>> Go To 10

NOTE: Remove the jumper wire before continuing.

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ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L

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P0172-FUEL SYSTEM 1/1 RICH (CONTINUED)

10.

(K41) O2 SENSOR 1/1 SIGNAL CIRCUIT

WARNING: When the engine is operating, do not stand in direct
line with the fan. Do not put your hands near the pulleys, belts, or
fan. Do not wear loose clothing. Failure to follow these instruc-
tions can result in personal injury or death.
Start the engine.

Measure the voltage on the (K41) O2 Sensor 1/1 Signal circuit in the
O2 Sensor harness connector.

Is the voltage above 4.8 volts?

Yes

>> Check the (K41) O2 Sensor 1/1 Signal circuit for damage,

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)

No

>> Go To 11

11.

(K902) O2 SENSOR RETURN UPSTREAM CIRCUIT

Engine still running.

Measure the voltage on the (K902) O2 Return Upstream circuit in the
1/1 O2 Sensor harness connector.

Is the voltage at 2.5 volts?

Yes

>> Go To 12

No

>> Check the (K902) O2 Return Upstream circuit for damage,

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)

NOTE: Turn the ignition off before continuing.

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ENGINE - ELECTRICAL DIAGNOSTICS - 3.7L/4.7L/5.7L

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P0172-FUEL SYSTEM 1/1 RICH (CONTINUED)

12.

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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