1993 Ford Aerostar Repair Question
Air bag code
13. Circuit shorted to ground.
Where do I begin diagnosing ?
Recently replaced battery.
CODE 13, FRONT IMPACT SENSOR OR AIR BAG CIRCUIT SHORTED TO GROUND
NOTE:Before proceeding, follow air bag service precautions.
After servicing has been performed, recheck AIR BAG warning light for codes with Air Bag Simulator (105-00010) still in place of air bag module. If system checks okay, install air bag module and reactivate air bag system.
CAUTION:DO NOT replace diagnostic monitor with a Code 13 present unless instructed to do so.
Diagnostic monitor measures voltage at terminal No. 11 at diagnostic monitor connector. Voltage at terminal No. 11 varies with charging system voltage. Note that circuits No. 614 (Gray/Orange wire) and No. 615 (Gray/White wire) are connected through driver-side air bag.
Also, note that circuit No. 615 is connected to front impact sensor feed circuits No. 617 (Pink/Orange wire) and No. 619 (Pink/White wire) through a diode inside of diagnostic monitor. If diagnostic monitor measures a voltage of 2 volts or less at terminal No. 11, Code 13 will set. When Code 13 sets, diagnostic monitor blows its internal thermal fuse. This disables air bag deployment circuit. If short to ground is corrected, voltage at terminal No. 11 will return to normal and a fault Code 51 will set, indicating an open thermal fuse.
Code 13 will set if a short to ground is present in circuits No. 614, 615, 623, 617 or 619. Code 13 will also set if clockspring is shorted to ground, safing sensor is internally shorted to ground, one or more impact sensors are shorted to ground, or there is an internal short to ground in driver-side air bag.
VERIFY CONDITION - Turn ignition on. Check for fault codes. If Code 13 is flashing, go to step 2). If Code 13 is not flashing, check connectors, wiring, splices and crimps for an intermittent problem. DO NOT proceed with diagnostic test until code is flashing. Failure to do so will result in needless replacement of diagnostic monitor.
CHECK FOR SHORTED AIR BAG - Deactivate air bag system. Carefully disconnect driver-side air bag. Try not to disturb wiring. Turn ignition on. Check for codes. If Code 13 is flashing, go to step 3). If Code 13 is not flashing, go to step 6).
CHECK FOR SHORTED WIRING - Set DVOM to AUTO or 2000 ohms scale. Disconnect negative battery cable. Check for continuity between terminal No. 3 (Black wire) and terminal No. 11 (Gray/Orange wire) of diagnostic monitor Black connector. If continuity exists (short to ground), go to step 4). If continuity does not exist, measure resistance between terminal No. 3 (Black wire) and No. 17 (Pink/Orange wire) and No. 18 (Pink/White wire) of diagnostic monitor connector. If both resistance readings are 777-797 ohms, go to step 7). If one or both resistance readings is not 777-797 ohms, go to step 5).
CHECK CLOCKSPRING RESISTANCE - Check for pinched and/or chafed clockspring wires at main wiring harness connector, located below steering column. If wiring is damaged, repair wiring and go to step 7). If wiring is okay, remove Air Bag Simulator (105-00010) from driver-side air bag connector. Disconnect clockspring from main wiring harness at base of steering column. Connect air bag simulator to main wiring harness in place of clockspring connector. Check for continuity between ground and terminal No. 11 of diagnostic connector. If terminal No. 11 is still shorted to ground, locate and repair short to ground in circuit No. 623, 614 or 615. If terminal No. 11 is no longer shorted to ground, replace clockspring and go to step 7).
LOCATE SHORTED SENSOR WIRING - Locate and disconnect appropriate front impact sensor that did not have a resistance reading of 777-797 ohms in step 3). Measure resistance between impact sensor terminals. If resistance is 777-797 ohms, impact sensor is okay. Repair short to ground in impact sensor wiring. After repair is completed, go to step 7). If resistance is not 777-797 ohms, replace impact sensor. Go to step 7).
CHECK CLOCKSPRING - Check clockspring for chafed or pinched wires. If wires are damaged, replace clockspring and go to step 7). If wires are okay, replace air bag module and go to step 7).
SHORT TO GROUND REPAIRED OR CORRECTED - After a short to ground has been corrected, diagnostic monitor will flash a Code 51. Code 51 indicates that thermal fuse inside of diagnostic monitor is blown and short to ground no longer exists. If short to ground has not been located and repaired (short to ground corrected itself), short is intermittent. If short to ground has been repaired, go to CODE 51 diagnostic test.
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