Dodge Ram Truck 1500-2500-3500. Manual — part 1270

P1682-CHARGING SYSTEM VOLTAGE TOO LOW (CONTINUED)

5.

(K125) GEN FIELD SOURCE CIRCUIT OPEN

Ignition on, engine not running.

Carefully inspect all connectors for corrosion or spread terminals before continuing.

With the scan tool actuate the Generator Field Driver.

While backprobing, measure the voltage on the (K125) Generator Field Source circuit at back of Generator.

Is the voltage above 10.0 volts?

Yes

>> Go To 6

No

>> Repair the open in the (K125) Generator Field Source circuit.

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

6.

(K125) GEN FIELD SOURCE CIRCUIT SHORTED TO GROUND

Turn the ignition off.

Disconnect the PCM harness connectors.

Disconnect the Generator Field harness connector.

Measure the resistance between ground and the (K125) Generator
Field Source circuit in the PCM harness connector.

Is the resistance below 100 ohms?

Yes

>> Repair the short to ground in the (K125) Generator Field

Source circuit and replace the PCM.

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

No

>> Go To 7

7.

(K20) GEN FIELD CONTROL CIRCUIT OPEN

Measure the resistance of the (K20) Generator Field Driver circuit from
the Generator harness connector to the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 8

No

>> Repair the open in the (K20) Generator Field Control cir-

cuit.

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

9 - 2002

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P1682-CHARGING SYSTEM VOLTAGE TOO LOW (CONTINUED)

8.

GENERATOR FIELD COIL HIGH RESISTANCE

Measure resistance across the Generator Field Terminals at the Generator.

Is the resistance above 15 ohms?

Yes

>> Replace or repair the Generator as necessary.

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

No

>> Go To 9

9.

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

9 - 2003

P1687-NO CLUSTER BUS MESSAGE

9 - 2004

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

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P1687-NO CLUSTER BUS MESSAGE (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 on.

•

Set Condition:
The PCM has not received an expected Cluster Status Bus message from the instrument cluster within the last
20 seconds.

Possible Causes

(D25) OPEN BETWEEN PCM AND CLUSTER

(D25) SHORTED BETWEEN PCM AND CLUSTER

CLUSTER

PCM

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

Diagnostic Test

1.

NO CLUSTER BUS MESSAGE

Ignition on, engine not running.

With the scan tool, erase DTCs.

Cycle the ignition key on and off several times.

With the scan tool, read DTCs.

Does the DTC reset?

Yes

>> Go To 2

No

>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

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

2.

COMMUNICATE WITH CLUSTER

Ignition on, engine not running.

With the scan tool, attempt to communicate with the Instrument cluster.

Can communication be established with the Instrument Cluster?

Yes

>> Go To 3

No

>> Refer to the Communication Category of the Body Diagnostic Manual and perform the appropriate

symptom related to no communication with cluster.

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

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - SRT-10

9 - 2005