Dodge Ram Truck 1500-2500-3500. Manual — part 1111

P0643-HIGH VOLTAGE AT THE #2 SENSOR SUPPLY CIRCUIT (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 key on.

•

Set Condition:
Voltage detected on the #2 sensor supply circuit was above a calibrated value.

Possible Causes

FAN CLUTCH ASSEMBLY

(K668) 5-VOLT SHORTED TO VOLTAGE

INTERMITTENT CONDITION

ECM

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

Diagnostic Test

1.

FAN CLUTCH ASSEMBLY

Disconnect the Fan clutch harness connector.

NOTE: Check connectors - Clean/repair as necessary.
With the scan tool, read DTCs.

Did P0483 set?

Yes

>> Replace the Fan clutch assembly.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)

No

>> Go To 2

9 - 1366

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

DR/DH

P0643-HIGH VOLTAGE AT THE #2 SENSOR SUPPLY CIRCUIT (CONTINUED)

2.

(K668) 5-VOLT SHORTED TO VOLTAGE

Disconnect the ECM harness connectors.

Disconnect the Fan harness connector.

NOTE: Check connectors - Clean/repair as necessary.
Measure the voltage between the fan speed sensor (K668) 5-volt sup-
ply circuit and battery negative.

Is the voltage greater than 1 volt?

Yes

>> Repair the (K668) 5-volt supply shorted to voltage.

Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)

No

>> Go To 3

3.

ECM

Turn the ignition off.

Reconnect the ECM harness connectors.

Turn the ignition on.

Measure the voltage between the (K668) 5-volt supply circuit in the
sensor harness connector and battery negative.

Is the voltage greater than 6 volts?

Yes

>> Replace the ECM.

Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)

No

>> Refer to the INTERMITTENT CONDITION Symptom

(Diagnostic Procedure). (Refer to 9 - ENGINE - DIAGNO-
SIS AND TESTING)

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

9 - 1367

P0646-LOW VOLTAGE DETECTED AT THE A/C CLUTCH RELAY

9 - 1368

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

DR/DH

P0646-LOW VOLTAGE DETECTED AT THE A/C CLUTCH RELAY (CONTINUED)

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

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
When the ignition is on.

•

Set Condition:
When the signal from the A/C Clutch output does not match the signal from the A/C Clutch feedback.

Possible Causes

A/C CLUTCH RELAY

LOOSE CONNECTION

FUSED BATTERY SUPPLY

(C13) A/C SIGNAL CIRCUIT OPEN

(C13) A/C SIGNAL CIRCUIT SHORTED TO GROUND

INTERMITTENT CONDITION

ECM

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

Diagnostic Test

1.

CLUTCH CLICKING

Ignition on, engine not running.

With the scan tool, actuate the A/C clutch relay.

Can you hear the Relay clicking?

Yes

>> Go To 2

No

>> Go To 3

2.

LOOSE CONNECTION

Actuation still running.

While the relay is clicking, wiggle the wiring harness and connectors throughout the circuit.

Does this interrupt the clicking?

Yes

>> Repair the loose connection.

Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)

No

>> Go To 3

DR/DH

ENGINE - ELECTRICAL DIAGNOSTICS - DIESEL

9 - 1369