Normal Operation The air bag diagnostic monitor measures the voltage at Pins 2, 3, 4, and 5 of the air bag diagnostic monitor connector. The voltage at these pins is set by the air bag diagnostic monitor and varies with charging system voltage (the expected voltages are shown in the following table). If the air bag diagnostic monitor detects low voltage on any of these pins, the air bag diagnostic monitor will store in memory and flash out on the air bag indicator a DTC 13 to indicate a possible short to ground on these circuits. At the same time the air bag diagnostic monitor begins flashing out DTC 13, it attempts to disarm the air bag system to prevent inadvertent deployment of the air bag(s) by blowing the 10A battery fuse feeding air bag diagnostic monitor Pins 13 and 14. It attempts to blow the fuse by activating a solid state switch which shorts the battery feed at Pin 13 to sheet metal ground at the air bag diagnostic monitor's bracket. The air bag diagnostic monitor will make up to three attempts to blow this fuse, spaced one minute apart.
o If the air bag diagnostic monitor has blown the fuse and thus removed battery voltage at Pin 14, a DTC 12 will be stored (refer to DTC «12» and «52» for further details).
o If the air bag diagnostic monitor attempts to blow the 10A battery fuse three times and fails each time, a DTC 24 will be stored (refer to DTC «24» and «64» for further details).
o After the 10A fuse is blown or three attempts to blow it fail, the air bag diagnostic monitor will not attempt to disarm again until the DTC 13 condition has been serviced and cleared (refer to «Diagnostic Trouble Code Clearing» for further details).
o Should the short on Pins 2, 3, 4 or 5 be intermittent or repaired, the air bag diagnostic monitor will flash out a DTC 53 (or a higher priority DTC such as DTC 12 if one exists) on the next ignition switch cycle.
Possible Causes WARNING: SERVICING A DTC 13 WILL USUALLY OCCUR AFTER SERVICING OF A DTC 12 HAS BEEN COMPLETED. UNDER NO CIRCUMSTANCES SUBSTITUTE ANOTHER FUSE VALUE FOR THE 10A BATTERY FUSE. ANY FUSE OTHER THAN 10A MAY CAUSE DISARMING FAILURE AND MAY RESULT IN DANGER TO THE OCCUPANTS OF THE VEHICLE. DO NOT ATTEMPT TO REPLACE THE 10A BATTERY FUSE UNLESS THE AIR BAG SYSTEM FIRST HAS BEEN DEACTIVATED (SEE «DEACTIVATION» PROCEDURE FOR DETAILS). Low voltage at air bag diagnostic monitor Pins 2, 3, 4, or 5 can be caused by:
o A short to ground on Circuits 607 (LB/O), 614 (GY/O), 615 (GY/W), or 616 (PK/BK) causing the diagnostic voltage to drop.
o Resistance to ground on Circuits 617 (PK/O), 619 (PK/W), 624 (Y/W), 625 (Y/LG) or internal resistance to ground in either of the radiator primary crash sensors may activate an air bag diagnostic monitor circuit which may cause the voltage to drop.
o An internal short to ground within the air bag sliding contact (14A664) causing the driver side air bag circuit(s) to be shorted to ground.
o An internal short to ground within the driver side air bag module (043B13) or passenger side air bag module (044A74).
Electrical Schematic -- Diagnostic Trouble Code 13 ===============================
DTC 13: AIR BAG CIRCUIT SHORTED TO GROUND
13-1 UNDERSTAND FUNCTION
- Cycle the ignition switch to OFF and then to RUN and confirm that DTC 13 is flashing on the air bag indicator.
- Read the normal operation description for DTC 13.
- Examine the diagnostic trouble code schematic.
- Is the diagnostic trouble code operation well understood?
Yes GO to «13-2».
NOTE: This is a hard fault. The fault condition may not be cleared until it is serviced and flashes out as a DTC 53. Under normal circumstances a DTC 12 will have just been serviced.
No RE-EXAMINE appropriate descriptions and schematics. Failure to understand air bag system functions will result in needless replacement of system components and repeat service.
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DTC 13: AIR BAG CIRCUIT SHORTED TO GROUND
13-2 CHECK FOR SHORTED AIR BAG(S)
o Deactivate system. Carefully disconnect air bags during deactivation.
o Turn ignition switch from OFF to RUN.
o Is DTC 13 still flashing?
Yes GO to «13-3».
No GO to «13-7».
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DTC 13: AIR BAG CIRCUIT SHORTED TO GROUND
13-3 CHECK DRIVER CIRCUIT FOR SHORTS
o Disconnect air bag diagnostic monitor.
o Examine wiring and connector where air bag sliding contact mates to main vehicle harness underneath steering column.
o Check for pinched and/or chafed wires.
o Measure resistance between air bag diagnostic monitor harness connector Pin 2 (Circuit 614, GY/O) and Pin 18 (Circuit 57, BK).
o Is Pin 2 shorted to ground?
Yes LOCATE and SERVICE short to ground in Circuit 614 (GY/O), Circuit 615 (GY/W), or air bag sliding contact wiring. RECONNECT system. CYCLE ignition switch. PROCEED to the description, schematic, and pinpoint tests of the diagnostic trouble code that is flashing.
No GO to «13-4».
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DTC 13: AIR BAG CIRCUIT SHORTED TO GROUND
13-4 CHECK PASSENGER CIRCUIT FOR SHORTS
o Measure resistance between air bag diagnostic monitor harness connector Pin 5 (Circuit 607, LB/O) and Pin 18 (Circuit 57, BK).
o Is Pin 5 shorted to ground?
Yes LOCATE and SERVICE short to ground in Circuit 607 (LB/O) or Circuit 616 (PK/BK). RECONNECT system. CYCLE ignition switch. PROCEED to the description, schematic, and pinpoint tests of the diagnostic trouble code that is flashing.
No GO to «13-5».
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DTC 13: AIR BAG CIRCUIT SHORTED TO GROUND
13-5 CHECK PRIMARY SENSORS
o Measure resistance between air bag diagnostic monitor harness connector Pin 15 (Circuit 619, PK/W) and Pin 18 (Circuit 57, BK).
o Measure resistance between air bag diagnostic monitor harness connector Pin 16 (Circuit 617, PK/O) and Pin 18 (Circuit 57, BK).
o Are resistance readings infinite (open)?
Yes REPLACE air bag diagnostic monitor and bracket. RECONNECT system. VERIFY system. REACTIVATE system.
No GO to «13-6».
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DTC 13: AIR BAG CIRCUIT SHORTED TO GROUND
13-6 DETERMINE IF SENSOR OR WIRE IS SHORTED
o Disconnect radiator primary crash sensor corresponding to the circuit with resistance to ground found in Step 13-5.
o Measure resistance across normally open contacts of radiator primary crash sensor at the sensor connector.
o Is resistance reading infinite (open)?
Yes LOCATE and SERVICE resistance to ground in wiring harness on affected circuits. RECONNECT system. CYCLE ignition switch. PROCEED to the description, schematic, and pinpoint tests of the diagnostic trouble code that is flashing.
No REPLACE respective radiator primary crash sensor. RECONNECT system. CYCLE ignition switch. PROCEED to the description, schematic, and pinpoint tests of the diagnostic trouble code that is flashing.
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DO NOT ATTEMPT THE FOLLOWING UNLESS YOU KNOW EXACTLY WHAT YOU ARE DOING AND EXACTLY WHAT TYPE OF DVM YOU HAVE.
DTC 13: AIR BAG CIRCUIT SHORTED TO GROUND
13-7 DETERMINE WHICH AIR BAG MODULE IS SHORTED
o Make sure that shorting bar is properly installed in passenger side air bag connector.
WARNING: USE A HAND-HELD DIGITAL OHMMETER WITH LESS THAN 10MA SHORT-CIRCUIT CURRENT ON THE LOWEST RESISTANCE SCALE POSSIBLE (TYPICALLY 200 OHMS SETTING). FAILURE TO USE A METER OF THIS TYPE MAY CAUSE PERSONAL INJURY DUE TO AIR BAG DEPLOYMENT.
o Measure resistance between either of the terminals in the passenger side air bag connector and the metal case of the passenger side air bag module.
o Is resistance reading infinite (open)?
Yes REPLACE driver side air bag module. RECONNECT system. CYCLE ignition switch. PROCEED to the description, schematic, and pinpoint tests of the diagnostic trouble code that is flashing.
No REPLACE passenger side air bag module. RECONNECT system. CYCLE ignition switch. PROCEED to the description, schematic, and pinpoint tests of the diagnostic trouble code that is flashing.
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