Pinpoint Test A: DTCs P0645, P0646 and P0647
Climate Control System
Pinpoint Tests
Pinpoint Test A: DTCs P0645, P0646 and P0647
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, voltage is provided to the A/C clutch relay coil. When A/C is requested and A/C line pressures allow, a ground is provided to the A/C clutch relay coil from the PCM, energizing the A/C clutch relay.
- (Gasoline) DTC P0645 (A/C Clutch Relay Control Circuit) - The DTC sets when the PCM grounds the relay circuit and excessive current draw is detected on the relay circuit. The DTC also sets when the relay circuit is OFF and no voltage is detected on the relay circuit. The PCM expects to detect voltage coming through the relay coil to the relay circuit when it is not grounding it.
- (Diesel) DTC P0645 (A/C Clutch Relay Control Circuit) - The DTC sets when the relay circuit is OFF and no voltage is detected on the relay circuit. The PCM expects to detect voltage coming through the relay coil to the relay circuit when it is not grounding it.
- (Diesel) DTC P0646 (A/C Clutch Relay Control Circuit Low) - The DTC sets when the PCM detects a constant ground on the relay circuit.
- (Diesel) DTC P0647 (A/C Clutch Relay Control Circuit High) - The DTC sets when the PCM grounds the relay circuit and excessive current draw is detected on the relay circuit, indicating a direct short to voltage.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- A/C clutch relay
- PCM
PINPOINT TEST A: DTC P0645, P0646 and P0647
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A1 CHECK THE PCM DTCs
- Check for PCM DTCs.
- Is DTC P0645 present?
Yes
GO to A2.
No
If P0646 is present, GO to A4.
If P0647 is present, GO to A5.
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A2 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between ground and the A/C clutch relay socket, circuit CBB70 (YE/BU).
- Is the voltage greater than 10 volts?
Yes
CARRY OUT the A/C clutch relay component test.
If the relay tests OK, GO to A3.
No
VERIFY battery junction box (BJB) fuse 70 (10A) is OK. If OK, REPAIR circuit CBB70 (YE/BU) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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A3 CHECK CIRCUIT CH302 (WH/BN) FOR AN OPEN
Diesel Only
- NOTE: Diesel only.
- Measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and PCM C1232b-57, circuit CH302 (WH/BN), harness side.
Gasoline Only
- NOTE: Gasoline only.
- Measure the resistance between A/C clutch relay socket, circuit CH302 (WH/BN) and PCM C175e-3, circuit CH302 (WH/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
Gasoline only, GO to A4.
Diesel only, GO to A6.
No
REPAIR circuit CH302 (WH/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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A4 CHECK CIRCUIT CH302 (WH/BN) FOR A SHORT TO GROUND
- Ignition OFF.
DTC P0646 Diesel Only
- NOTE: DTC P0646 diesel only.
- Measure the resistance between ground and PCM C1232b-57, circuit CH302 (WH/BN), harness side.
DTC P0645 Gasoline Only
- NOTE: DTC P0645 gasoline only.
- Measure the resistance between ground and PCM C175e-3, circuit CH302 (WH/BN), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
Gasoline only, GO to A5.
Diesel only, GO to A6.
No
REPAIR circuit CH302 (WH/BN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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A5 CHECK CIRCUIT CH302 (WH/BN) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: (Diesel) PCM C1232b.
- Disconnect: (Gasoline) PCM C175e.
- Ignition ON.
DTC P0647 Diesel Only
- NOTE: DTC P0647 diesel only.
- Measure the voltage between ground and PCM C1232b-57, circuit CH302 (WH/BN), harness side.
DTC P0645 Gasoline Only
- NOTE: DTC P0645 gasoline only.
- Measure the voltage between ground and PCM C175e-3, circuit CH302 (WH/BN), harness side.
- Is any voltage present?
Yes
REPAIR circuit CH302 (WH/BN) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to A6.
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A6 CHECK THE PCM CONNECTION
- Clear the DTCs.
- Disconnect all the PCM connectors.
- Check for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the PCM connectors.
- Operate the system.
- Does the concern return?
Yes
INSTALL a new PCM. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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