P0647

P0647-HIGH VOLTAGE DETECTED AT THE A/C CLUTCH RELAY

P0647 - High Voltage Detected At The A/C Clutch Relay:

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
- Loose connection
- Shorted to external voltage
- Fused battery supply
- A/C clutch relay
- Intermittent condition
- ECM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. CLUTCH CLICKING
Ignition on, engine not running.
With the scan tool, actuate the A/C clutch relay.

Q: 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.

Q: Does this interrupt the clicking?

YES: Repair the loose connection. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 3

3. FUSED BATTERY SUPPLY
Ignition off.
Disconnect the ECM connectors.
Remove the A/C clutch relay.

NOTE: Check connectors - Clean/repair as necessary.

Ignition on, engine not running.
Measure the voltage on the Fused Battery Supply circuit between the PDC and battery negative.

Q: Is the voltage less than 1 volt?

YES: Go To 4
NO: Repair the short to voltage. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

4. A/C CLUTCH RELAY





Remove the A/C Clutch Relay from the PDC.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between terminals 85 and 86 of the A/C Clutch Relay.

Q: Is the resistance less than 10 Ohms?

YES: Go To 5
NO: Replace the A/C clutch relay. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1

5. ECM
Reconnect the ECM harness connectors.
Reinstall the A/C clutch relay.
With the scan tool, actuate the A/C clutch relay.
Turn the ignition on.
While monitoring with the scan tool, disconnect the A/C Clutch Relay from the PDC.

Q: Did DTC P0646 set?

YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
NO: Replace the ECM. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1