Dodge Ram Truck 1500-2500-3500. Manual — part 1269

P1599-A/C PRESSURE SENSOR VOLTAGE TOO LOW (CONTINUED)

7.

(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Measure the resistance between the (F855) 5-volt Supply circuit and
ground in the A/C Pressure Transducer harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the (F855) 5-volt Supply cir-

cuit.

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

No

>> Go To 8

8.

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)

9 - 1998

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P1682-CHARGING SYSTEM VOLTAGE TOO LOW

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

9 - 1999

P1682-CHARGING SYSTEM VOLTAGE TOO LOW (CONTINUED)

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

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
With the ignition key on and the engine running over 1500 RPM after 25 seconds.

•

Set Condition:
When the PCM regulates the generator field and there are no detected field problems, but the voltage output
does not increase.

Possible Causes

BATTERY TEMPERATURE SENSOR

RESISTANCE IN THE BATTERY POSITIVE CIRCUIT

(K125) GENERATOR FIELD SOURCE CIRCUIT OPEN

RESISTANCE IN THE GENERATOR GROUND

(K125) GENERATOR FIELD SOURCE CIRCUIT SHORTED TO GROUND

(K20) GENERATOR FIELD CONTROL CIRCUIT OPEN

RESISTANCE IN THE GENERATOR FIELD COIL

PCM

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

Diagnostic Test

1.

CHARGING VOLTAGE BELOW 15.1 VOLTS

Turn the ignition off.

NOTE: Battery must be fully charged and capable of passing a battery load test.

NOTE: Generator Belt tension and condition must be checked before continuing.

NOTE: Inspect the vehicle for any aftermarket accessories that may exceed the maximum Generator output.

WARNING: When the engine is operating, do not stand in direct line of the fan. Do not put your hands near
the pulley, belts, or fan. Do no wear loose clothing.
Start the engine.

Record all DTCs and the related Freeze Frame data.

With the scan tool, read the target charging voltage.

Is the target charging voltage above 15.1 volts?

Yes

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

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

No

>> Go To 2

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ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P1682-CHARGING SYSTEM VOLTAGE TOO LOW (CONTINUED)

2.

BATTERY TEMPERATURE SENSOR

Turn the ignition off.

NOTE: Generator Belt tension and condition must be checked before continuing.
Start the engine.

Allow the engine to reach normal operating temperature.

With the scan tool in sensors, read the Battery Temp Sensor value.

Using a Thermometer, measure under hood temperature.

Is the temperature within 10° F of Battery temperature?

Yes

>> Go To 3

No

>> Replace the Battery Temperature Sensor.

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

3.

HIGH RESISTANCE IN THE BATTERY POSITIVE CIRCUIT

Ignition on, engine not running.

Measure the voltage between the Generator B+ Terminal and the Battery Positive Post.

WARNING: When the engine is operating, do not stand in direct line of the fan. Do not put your hands near
the pulley, belts, or fan. Do no wear loose clothing.

CAUTION: Make sure all wires are clear of the engine’s moving parts.
Start the engine.

Is the voltage above 0.4 of a volt?

Yes

>> Repair the excessive resistance in the Battery Positive circuit between the Generator and Battery.

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

No

>> Go To 4

4.

RESISTANCE IN THE GENERATOR GROUND

Start the engine.

WARNING: When the engine is operating, do not stand in direct line of the fan. Do not put your hands near
the pulley, belts, or fan. Do no wear loose clothing.
Warm the engine to operating temperature.

CAUTION: Make sure all wires are clear of the engine’s moving parts.
Measure the voltage between the Generator case and Battery Negative Post.

Is the voltage above 0.1 of a volt?

Yes

>> Repair the excessive resistance in the Generator Ground circuit between the Generator Case and Bat-

tery Negative side.

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

No

>> Go To 5

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

9 - 2001