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DTC Troubleshooting

DIAGNOSIS PROCEDURE - DTC P0646 A/C COMPRESSOR RELAY LOW INPUT

Step Action Value(s) Yes No
1 Perform an On-Board Diagnostic (OBD) System Check.
Is the system check complete?		 - Go to Step 2. Go to "ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK ".
2
  1. Turn the ignition switch to LOCK.
  2. Disconnect the A/C compressor relay.
  3. Measure the resistance between A/C compressor relay terminals 85 and 86.

Does the resistance within the specified value?		 0 Ω Go to Step 3. Go to Step 7.
3
  1. Turn the ignition switch to LOCK.
  2. With the test light, connected to ground, probe the ignition feed circuit, at terminal 86 in the relay harness connector.

Does the test light illuminate?		 - Go to Step 5. Go to Step 4.
4 Repair a short to ground between the ignition switch and A/C compressor relay terminal 86.
Is the repair complete?		 - Go to Step 9. -
5
  1. Turn the ignition switch to LOCK.
  2. Disconnect the ECM.
  3. With the test light, connected to ground, probe the ignition feed circuit, at terminal 86 in the relay harness connector.

Does the test light illuminate?		 - Go to Step 8. Go to Step 6.
6 Repair a short to ground between the ECM wiring connector terminal 106 and A/C compressor relay terminal 86.
Is the repair complete?		 - Go to Step 9. -
7 Replace the A/C compressor relay.
Is the replacement complete?		 - Go to Step 9. -
8
  1. Turn the ignition switch to LOCK.
  2. Replace the ECM.

Is the repair complete?		 - Go to Step 9. -
9
  1. Using the scan tool, clear the Diagnostic Trouble Codes (DTCs).
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the Conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has run and passed?		 - Go to Step 10. Go to Step 2.
10 Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?		 - Go to applicable DTC TABLE . System OK
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