Pinpoint Test B: DTC P0645:13, P0646:11 Or P0647:12
Climate Control System
Pinpoint Test B: DTC P0645:13, P0646:11 or P0647:12
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information Electrical Diagrams.
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.
- DTC P0645:13 (A/C Clutch Relay Control Circuit: Circuit Open)- This 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.
- DTC P0646:11 (A/C Clutch Relay Control Circuit Low: Circuit Short To Ground)- This DTC sets when the relay circuit is OFF and ground 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.
- DTC P0647:12 (A/C Clutch Relay Control Circuit High: Circuit Short To Battery)- This DTC sets when the PCM grounds the relay circuit and excessive current draw (short to voltage) is detected on the relay circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- A/C clutch relay
- PCM
PINPOINT TEST B : DTC P0645:13, P0646:11 OR P0647:12
B1 CHECK PCM DTCS
- Ignition ON.
- Check the PCM DTCs retrieved during the self-test.
Is DTC P0645:13 present?
Yes
GO to B2.
No
For DTC P0646:11, GO to B5.
For DTC P0647:12, GO to B6.
B2 CHECK THE VOLTAGE TO THE A/C CLUTCH RELAY COIL
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between ground and the A/C clutch relay socket pin 1, circuit CBP02 (GN).
Is the voltage greater than 10 volts?
Yes
GO to B3.
No
VERIFY Central Junction Box (CJB) fuse 2 (10A) is OK. If OK, REPAIR circuit CBP02 (GN) 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 Electrical Diagrams.
B3 CHECK THE A/C CLUTCH RELAY
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning or equivalent. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- Start the engine.
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
- With the engine running, connect a 12-volt test light between A/C clutch relay socket pin 1, circuit CBP02 (GN) and A/C clutch relay socket pin 2, circuit CH302 (WH/BN).
Does the test light illuminate?
Yes
INSTALL a new A/C clutch relay. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to B4.
B4 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: PCM C175B.
- Measure the resistance between A/C clutch relay socket pin 2, circuit CH302 (WH/BN) and PCM C175B-25, circuit CH302 (WH/BN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to B7.
No
REPAIR circuit CH302 (WH/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
B5 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Disconnect: PCM C175B.
- Measure the resistance between ground and PCM C175B-25, circuit CH302 (WH/BN), harness side.
Is the resistance greater than 10,000 ohms?
Yes
GO to B7.
No
REPAIR circuit CH302 (WH/BN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
B6 CHECK THE A/C CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Disconnect: PCM C175B.
- Ignition ON.
- Measure the voltage between ground and PCM C175B-25, 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
CARRY OUT the A/C clutch relay component test.
If the relay tests OK, GO to B7.
B7 CHECK THE PCM CONNECTION
- Disconnect all the PCM connectors.
- Inspect the PCM connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the PCM connectors.
- Operate the system and verify the concern is still present.
Is the concern still present?
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.