P0646

AC : P0646, P0647. Air Conditioning Clutch Relay Drive.

AC1 : CHECK THE GROUND SUPPLY TO THE AIR CONDITIONING CLUTCH.

WARNING: THIS TEST INVOLVES WORKING IN PROXIMITY TO ROTATING PARTS. MAKE SURE DUE CARE IS EXERCISED.

1. Turn the ignition switch to the ON position,
2. Disconnect the PCM electrical connector, PI01.
3. Disconnect the air conditioning clutch electrical connector, PI49.
4. Measure the resistance between PI49, pin 2, (B) and GROUND.

Is the resistance less than 5 ohms?

Yes
Repair the circuit between PI49, pin 2, (B) and GROUND. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

No
Goto AC2

AC2 : CHECK THE CIRCUIT INTEGRITY BETWEEN THE PCM AND THE AIR CONDITIONING CLUTCH.
1. Apply a GROUND to the disconnected PCM electrical connector, PI01, pin 34 (BG)
2. Measure the voltage at air conditioning clutch electrical connector, PI49, pin 1 (RG)

Is the voltage greater than 10 volts?

Yes
Goto AC3

No
Goto AC4

AC3 : CHECK THE AIR CONDITIONING CLUTCH RELAY TO PCM CIRCUIT FOR SHORT TO GROUND.
1. Measure the resistance between PI01, pin 34 (BG) and GROUND.

Is the resistance less than 10,000 ohms?

Yes
Goto AC4

No
Install a new air conditioning compressor clutch relay. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation. If the DTC is repeated, INSTALL a new PCM.

AC4 : CHECK THE CIRCUIT BETWEEN THE AIR CONDITIONING COMPRESSOR CLUTCH AND THE RELAY FOR SHORT TO BATTERY.
1. Measure the voltage between PI49, pin 1 (RG) and GROUND.

Is the voltage greater than 5 volts?

Yes
Repair the short circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

No
Goto AC5

AC5 : CHECK THE CIRCUIT BETWEEN THE AIR CONDITIONING COMPRESSOR CLUTCH AND THE ACCC RELAY FOR SHORT TO GROUND.
1. Measure the resistance between PI49, pin 1 (RG) and GROUND.

Is the resistance less than 10,000 ohms?

Yes
Repair the short circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

No
Goto AC6

AC6 : CHECK THE CIRCUIT BETWEEN FUSE 32 OF THE FRONT POWER DISTRIBUTION FUSE BOX AND THE ACCC RELAY FOR SHORT TO GROUND.
1. Remove fuse 32.
2. Measure the resistance between fuse box electrical connector, FH32, pin 38 and GROUND.

Is the resistance less than 10,000 ohms?

Yes
Repair the short circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

No
Goto AC7

AC7 : CHECK THE ACCC RELAY BASE FOR BATTERY VOLTAGE AT PIN 3.
1. Refit fuse 32.
2. Measure the voltage between the ACCC relay base, pin 3 and GROUND.

Is the voltage greater than 10 volts?

Yes
Goto AC8

No
Check/replace fuses. Repair the circuit between the relay base and the battery power bus 1. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

AC8 : CHECK THE CIRCUIT BETWEEN PIN 1 OF THE ACCC RELAY BASE AND THE POWER DISTRIBUTION FUSE BOX FOR SHORT TO GROUND.
1. Remove fuse 38.
2. Measure the resistance between the ACCC relay base, pin 1 and GROUND.

Is the resistance less than 10,000 ohms?

Yes
Repair the short circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

No
Goto AC9

AC9 : CHECK THE ACCC RELAY BASE FOR BATTERY VOLTAGE AT PIN 1
1. Refit fuse 38.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between ACCC relay base, pin 1, and GROUND.

Is the voltage greater than 10 volts?

Yes
Goto AC10

No
Check/replace fuses. Repair the circuit between the relay base and the battery power bus 2. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.
This circuit includes the EMS relay, and fuses 9.

AC10 : CHECK THE CIRCUIT BETWEEN THE PCM AND THE ACCC RELAY BASE FOR CONTINUITY.
1. Remove the ACCC relay.
2. Measure the resistance between the PCM electrical connector, PI01, pin 34 (BG) and ACCC relay base, pin 2.

Is the resistance less than 5 ohms?

Yes
Goto AC11

No
Repair the circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

AC11 : CHECK THE CIRCUIT BETWEEN THE PCM AND THE ACCC RELAY BASE FOR SHORT TO BATTERY.
1. Check for a voltage between the PCM electrical connector, PI01, pin 34 (BG) and GROUND.

Is the voltage greater than 5 volts?

Yes
Repair the short circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

No
Goto AC12

AC12 : CHECK THE CIRCUIT BETWEEN THE PCM AND THE ACCC RELAY BASE FOR SHORT TO GROUND.
1. Measure the resistance between the PCM electrical connector, PI01, pin 34 (BG) and GROUND.

Is the resistance less than 10,000 ohms?

Yes
Repair the short circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

No
Install a new ACCC relay. CLEAR the DTC. TEST the system for normal operation.