Chrysler Town, Dodge Caravan. Manual - part 624

TEST

ACTION

APPLICABILITY

Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing 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 DRBIII

t, actuate the ASD Fuel System test and observe the fuel pressure

gauge.
NOTE: Fuel pressure specification is 400 KPa +/- 34 KPa (58 psi +/- 5 psi).
Turn the ignition off.
Choose a conclusion that best matches your fuel pressure reading.

All

Within Specification

Go To

Below Specification

Go To

Caution: Stop All Actuations.

NOTE: If one of the O2 Sensors Signal or Return circuits are shorted to
ground or voltage, all the other O2 Sensor voltage readings will be affected.
NOTE: After the repairs have been made, verify proper O2 Sensor operation.
If all the O2 Sensor voltage readings have not returned to normal, follow the
diagnostic procedure for the remaining O2 Sensors.
Start the engine.
Allow the engine to reach normal operating temperature.
With the DRBIII

t, read the O2 Sensor voltage.

Is the voltage switching between 2.5 and 3.4 volts?

All

Yes

→ Go To 4

→ Go To 9

Turn the ignition off.
NOTE: Allow the O2 Sensor to cool down before continuing the test. The O2
voltage should stabilize at 5.0 volts. Raising the hood may help in reducing
under hood temps.
Ignition on, engine not running.
With the DRBIII

t, actuate the O2 Heater Test.

With the DRBIII

t, monitor O2 Sensor voltage for at least 2 minutes.

Does the voltage stay above 4.5 volts?

All

Yes

→ Replace the O2 Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

→ Go To 5

Ignition on, engine not running.
With the DRBIII

t, read the TP Sensor voltage.

While monitoring the DRBIII

t, slowly open and close the throttle.

Does the voltage increase and decease smoothly?

All

Yes

→ Go To 6

→ Replace the Throttle Position Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

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P0171-FUEL SYSTEM 1/1 LEAN —

Continued

TEST

ACTION

APPLICABILITY

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 DRBIII

t in Sensors, read the MAP Sensor vacuum value.

Is the DRBIII

t reading within 19 of the Vacuum Gauge reading?

All

Yes

→ Go To 7

→ Replace the MAP Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

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 DRBIII

t, read the Engine Coolant Temperature (ECT) 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 ECT Sensor value. The temperature value
change should be a smooth transition from start up to normal operating temperature
82°C (180°F). The value should reach at least 82°C (180°F).
Did the ECT value increase with a smooth transition and did it reach at least 82°C?

All

Yes

→ Go To 8

→ Replace the Engine Coolant Temperature Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

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?

All

Yes

→ Repair as necessary.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

→ Test Complete.

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P0171-FUEL SYSTEM 1/1 LEAN —

Continued

TEST

ACTION

APPLICABILITY

Ignition on, engine not running.
Disconnect the O2 Sensor harness connector.
With the DRBIII

t, monitor the O2 Sensor voltage.

The O2 Sensor voltage should read 5.0 volts on the DRBIII

t with the connector

disconnected.
Using a jumper wire, jump across the O2 Sensor harness connector from the O2
Signal circuit to the O2 Return circuit at 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 volts change from 5.0 volts to 2.5 volts?

All

Yes

→ Replace the O2 Sensor

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

→ Go To 10

Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Ignition on, engine not running.
With the DRBIII

t, monitor the O2 Sensor voltage.

Is the voltage above 4.8 volts?

All

Yes

→ Go To 11

→ Check the O2 Signal circuit 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 in accordance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Ignition on, engine not running.
Measure the voltage on the O2 Return circuit in the O2 Sensor harness connector.
Is the voltage at 2.5 volts?

All

Yes

→ Check the fuel system for contaminates. Also, check the exhaust

system for any leaks.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

→ Check the O2 Return circuit for a short to ground, open, or short

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P0171-FUEL SYSTEM 1/1 LEAN —

Continued

TEST

ACTION

APPLICABILITY

Turn the ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
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 the disconnected fuel line
and the fuel pump module.
Turn the ignition on.
With the DRBIII

t, actuate the ASD Fuel System test and observe the fuel pressure

gauge.
NOTE: Fuel pressure specification is 400 KPa +/- 34 KPa (58 psi +/- 5 psi).
Is the fuel pressure within specification?

All

Yes

→ Repair or replace fuel supply line as necessary.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

→ Go To 13

Caution: Stop All Actuations.

All

Yes

→ Replace the Fuel Pump Inlet Strainer.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

→ Go To 14

If there are no possible causes remaining, view repair.

All

Repair

Replace the Fuel Pump Module.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.

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P0171-FUEL SYSTEM 1/1 LEAN —

Continued

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