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DTC B1079: A/C refrigerant leak
 
 
 
 
 
 
DTC SET CONDITION
DTC B1079 will be set when the A/C pressure sensor detects the refrigerant pressure of specified level or less.
noteWhen DTC B1079 is set, the A/C indicator of A/C control panel flashes.
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
  • The refrigerant amount is not at the specified level, or the wiring harness or connector between the A/C control panel and A/C pressure sensor, and the A/C control panel itself or A/C pressure sensor itself may have failed.
Past trouble
  • If DTC B1079 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) between the A/C control panel and the A/C pressure sensor. If the connectors and wiring are normal, and obviously the ECU is the cause of the trouble, replace the ECU. If in doubt, do not replace the ECU.
 
 
 
TROUBLESHOOTING HINT
  • Malfunction of connector.
  • Malfunction of the harness.
  • Malfunction of the A/C pressure sensor.
  • Malfunction of the A/C control panel.
 
 
 
DIAGNOSIS
Required Special Tool:
  • MB991658: Test harness set
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Using scan tool MB991958, diagnose the CAN bus line
(1)
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the CAN bus line found to be normal?
Go to Step 2.
Repair the CAN bus line. (Refer to GROUP 54C, Diagnosis ).
 
STEP 2. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is set.
Is the DTC set?
Go to Step 3.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 3. Check A/C pressure sensor connector A-63 and A/C control panel connector C-216 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Are air A/C pressure sensor connector A-63 and A/C control panel connector C-216 in good condition?
Go to Step 4.
Repair or replace the connector. Refer to GROUP 00E, Harness Connector Inspection .
 
STEP 4. Check the wiring harness between A/C control panel connector C-216 (terminals 12, 11 and 6) and A/C pressure sensor connector A-63 (terminals 3, 2 and 1).
noteAlso check intermediate connector C-128 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-128 is damaged, repair or replace the connector as described in GROUP 00E, Harness Connector Inspection .
  • Check the sensor signal line and ground line for open or short circuit.
Is the wiring harness between A/C control panel connector C-216 (terminals 12, 11 and 6) and A/C pressure sensor connector A-63 (terminals 3, 2 and 1) in good condition?
Go to Step 5.
Repair the wiring harness.
 
STEP 5. Check the A/C pressure sensor operation.
(1) Assemble a gauge manifold on the high pressure service valve.
(2) Disconnect the A/C pressure sensor connector and connect special tool test harness MB991658 as shown in the illustration.
(3) Turn ON the engine and then turn ON the A/C switch.
(4) At this time, check to see that the voltage of A/C pressure sensor terminal No. 2 reflects the specifications of the figure.
noteThe allowance shall be defined as ±5%.
Is the A/C pressure sensor operating properly?
Go to Step 6.
Replace the A/C pressure sensor. Then go to Step 7.
 
STEP 6. Check the refrigerant level.
Use the refrigerant recovery station to remove all of the refrigerant, and then calculate the amount of the refrigerant and charge it.
Is the refrigerant level correct?
Go to Step 7.
Correct the refrigerant level (Refer to On-vehicle Service ). Then go to Step 7.
 
STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect scan tool MB991958 to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Return to Step 1.
The procedure is complete.