air bag light, can someone help?

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1994bronco

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i have a 1994 ford bronco, and the air bag light flashes all the time. i dont no any thing about air bags and i dont want it to go off in my face.i cant find any wiring diagrams or anything on it, if any one knows about this i would really appreciate it.

 

Rons beast

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This usually means a malfunction in the deployment circuit, or the bag needs replacement. It could be a minor short from a wire rubbing to ground.

Maybe someone else here can find a source for the wiring circuit. If so you can start at the circuit termination and trace the wireing back to the fuse.

I know of no check for the sensors, but there must be some. Try a google search.

 

Rons beast

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Update...turn the key to the run position, and the light will flash a 2 digit code. The code will guide you to a depleted airbag battery, clockspring needs replaced, or circuit power loss. Get the code and google the result.

 
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miesk5

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yo, Good stuff!

Testing, Wiring Diagram, Operation & Troubleshooting for 94-96;

"The air bag diagnostic monitor (14B056) continually monitors all supplemental air bag restraint system components and wiring connections for possible faults in the system. If the air bag diagnostic monitor detects a fault in the supplemental air bag restraint system when the key is in RUN, a diagnostic trouble code will be displayed on the air bag indicator, located in the instrument cluster (10849).

Performing system diagnostics is the main purpose of the air bag diagnostic monitor. Note: The air bag diagnostic monitor does not deploy the air bag in the event of a crash. The LH and RH primary crash sensors are hard wired to the air bag; therefore, the LH and RH primary crash sensors and RH safing sensor and bracket sensor (also called the Rear Air Bag Sensor) determine when to deploy the air bag. Features and functions of the air bag diagnostic monitor are described below. *

The air bag diagnostic monitor illuminates the air bag indicator for approximately six seconds when the key is in RUN and then turns the indicator off. This shows that the air bag indicator is operational. If the air bag indicator does not illuminate or the indicator stays on or flashes at any time, a fault has been detected by the air bag diagnostic monitor. * Diagnostic trouble codes may not be displayed for approximately 30 seconds after the key is placed in RUN. This is the amount of time the air bag diagnostic monitor requires to perform all tests and verify system faults, if present.

* Each diagnostic trouble code (a series of flashes and pauses of the air bag indicator) represents a two-digit number. Each diagnostic trouble code is always displayed at least twice. For example, a diagnostic trouble code 32 is displayed as three flashes, followed by a one-second pause, then two flashes, followed by a three-second pause. * If a system fault is present and the air bag indicator is malfunctioning, an audible tone will be heard, indicating that system service is required. The tone is a series of five sets of five beeps. This does not indicate a diagnostic trouble code 55. If the tone is heard, the air bag indicator is inoperative and a system fault that requires service is present.

CAUTION: The thermal fuse does not blow (open) because of excessive current flowing through it. DO NOT attempt to jumper out the thermal fuse with a circuit breaker or any other type of fuse. * If a fault exists that makes unwanted air bag deployment possible, the air bag diagnostic monitor has an internal thermal fuse that will blow (open) automatically. This removes all power to the air bag deployment circuit.

* The air bag indicator will flash the appropriate diagnostic trouble code to indicate the suspect circuit. If the indicator is malfunctioning the tone will be heard.

* Diagnostic trouble codes are prioritized numerically so if two or more different faults occur at the same time, the fault having the highest priority will be displayed first. After that fault has been corrected, the next highest priority fault will be displayed. * The air bag diagnostic monitor includes an internal backup power supply. This feature provides sufficient backup power to deploy the air bag in the event the battery or battery cables are damaged in an accident before safing and primary crash sensors close. The backup power supply will deplete its stored energy approximately one minute after the positive battery cable is disconnected.

Airbag DIagnostic Monitor (ADM) Light Flash Code (LFC) Priority Table Tone (5 Beeps Repeated 4 Times): Air Bag Indicator Open Circuit with Stored Fault Code(s)

No Air Bag Indicator (Dash Light Out): Inoperative Indicator Circuit or No Battery Voltage to ADM

Continuous Air Bag Indicator: ADM Disconnected or Inoperative

12: Low Battery Voltage

13: Air Bag Circuit Shorted to Ground

14: Front Air Bag Sensor and Bracket Circuit Shorted to Ground

21: Rear Air Bag Sensor and Bracket Not Mounted to Vehicle Properly

22: Rear Air Bag Sensor and Bracket Output Circuit Shorted to Battery Voltage

23: Rear Air Bag Sensor and Bracket Circuit Input Feed/Return Circuit Open

24: Rear Air Bag Sensor and Bracket Output Feed/Return Circuit Open

32: Driver Side Air Bag Circuit High Resistance or Open

34: Driver Side Air Bag Circuit Low Resistance or Shorted

41: RH Front Air Bag Sensor and Bracket Feed/Return Circuit Open

42: LH Front Air Bag Sensor and Bracket Feed/Return Circuit Open

44: RH Front Air Bag Sensor and Bracket Not Mounted to Vehicle Properly

45: LH Front Air Bag Sensor and Bracket Not Mounted to Vehicle Properly

51: ADM Internal Thermal Fuse Blown Due to Intermittent Short to Ground

52: Backup Power Supply Voltage Boost Fault

53: Front Air Bag Sensor and Bracket Circuits Resistance to Ground or ADM Fault

Rapid Continuous Flashing (No Fault Code): All Primary Air Bag Sensors Disconnected

Source: by Ford via Steve83 (Steve, That dirty old truck) at SuperMotors.net

airbagcircuit96.jpg

FUSE BLOCK Diagram in a 94 Bronco & F-Series

Source: by Steve83 (Steve, That dirty old truck) at SuperMotors.net

Fuses 5 & 18 to Module and 17 to Indicator Lamp & Chime;

fuses94gas.jpg

 
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1994bronco

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thanks for the info, i will try those and see what happens. thanks again..

 
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1994bronco

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i got code 51, internal thermal fuse blown. how would i fix this?

 

miesk5

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yo,

NOTE: The diagnostic monitor contains an internal thermal fuse that is not serviceable. The thermal fuse is controlled by the diagnostic monitor. The diagnostic monitor will blow the thermal fuse whenever a short on the deployment circuits occurs. The thermal fuse does not blow because of excessive current flowing through it. DO NOT attempt to jumper out the thermal fuse with a circuit breaker or any other type of fuse.

WARNING: DO NOT INSTALL A NEW DIAGNOSTIC MONITOR UNTIL THE SHORT HAS BEEN LOCATED AND CORRECTED. IF A SHORT TO GROUND HAS NOT BEEN LOCATED AND CORRECTED, THEN THE SHORT TO GROUND IS INTERMITTENT AND IS NOT PRESENT AT THIS TIME. INSTALLING A NEW DIAGNOSTIC MONITOR WITH AN INTERMITTENT SHORT IN THE SYSTEM WILL RESULT IN REPEAT BLOWN DIAGNOSTIC MONITORS AND REPEAT SERVICE.

The diagnostic monitor measures the voltages at the diagnostic monitor connector Pins. When certain air bag deployment wires are shorted to ground (heavy lines illustrated in the electrical schematic above), the system may become susceptible to unwanted deployment of the air bag(s). The diagnostic monitor senses a short to ground on any of these circuits and helps prevent unwanted air bag deployment by blowing the diagnostic monitor thermal fuse. Blowing this fuse removes all power (battery and back-up power) from the air bag deployment circuits. While the short to ground exists, the monitor will flash diagnostic trouble code 13 or code 14, depending on where the short appears (see code 13 and 14 for more details). If the short to ground is intermittent and temporarily corrects itself, the diagnostic monitor will flash code 51.

NOTE: If the short to ground returns, the higher priority codes 13 or 14 will be flashed instead of 51.

If the Air Bag indicator is flashing code 51 and a short to ground has not been serviced, this means that an intermittent short to ground exists in the air bag system. The diagnostic monitor should be replaced only after service of the intermittent short has been completed.

Some service tips for finding an intermittent short to ground are:

Consult OASIS (Restraint Systems service Code 104000) for up to date diagnostics and descriptions of wiring concern locations for the vehicle (VIN number) you are working on. OASIS is updated daily using concern descriptions from engineering and Dealership Service sources.

2. Inspect wiring and harnesses in areas where they pass through or are located next to metal components (i.e. engine compartment bulkhead, body sheet metal, component mounting brackets, etc.)

Check Front Sensor/ wiring First

Sensor, Front Location & pics in a 96; on the left and right front radiator supports Source: by ThetaTauMan (Rob, UTURNOB163) at SuperMotors.net

img_0328.jpg

Check passenger side B Pillar for the short; remove trim

& on the left and right front radiator supports

Sensor, Rear Air Bag Sensor and Bracket Assembly Location, pass. side B pillar pics in a 96 Source: by Tool38 (Bronc) at SuperMotors.net

airbag-(1).jpg

miesk5 Note, the Rear Air Bag Sensor and Bracket Assembly is also called the RH Safing Sensor; The sensors are an electrical switch which reacts to impacts according to direction and force. It discriminates between impacts that require air bag deployment and impacts that do not. When an impact occurs that requires deployment, the sensor contacts close, completing the electrical circuit necessary for the system to operate. The safing and one of the primary sensors must be activated simultaneously to inflate the air bag.

Air Bag Dis-Arming Video & Connector Location in a 94; "...how to disarm a ford airbag. the backup power supply can still set off the airbag up to a full minute after the battery is disconnected so be sure to give it ample time to deplete.if the bag goes off on you i cannot be held responsible..." Source: by pfun41 at youtube.com


Diagnostic Monitor Thermal Fuse Replacement Video in a 94; "...WARNING: working on airbag systems is inherently dangerous. should you choose to do anything depicted in the video i cannot be held responsible for anything that may happen. My bronco was flashing a code 51. this stands for "internal adm fuse blown due to intermittant short to ground". the general repair for this is to fix the short and replace the aibag diagnostic monitor. i called the junkyard and they wanted $55! so i decided that instead of replacing the whole thing i would only replace the component that was broken. the thermal fuse in the ADM is 168 deg C, this is a hard to find temp rating so i bought some rated 1 degree lower at 167 deg C. i bought mine from newark.com. the ones i bought ended up being slightly larger that the original so i had to modify the fuse's casing to fit it. in retrospect if you were to do something like this it would be easier to remove the fuse assemby from a ADM in a vehicle with a deployed airbag, just make shure the fuse itself has continuity. if you show the fuse to the people at the junkyard the fuse and they ask what its from make something up or tell them its from a blown airbag module. this method would require less modifying and would look much more professional. applies to 1994-1996 broncos and f150s..." Source: by pfun41 at youtube.com

 

miesk5

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yo,

this is from my 96's service manual which is most likely same as your yr.

"Diagnostic Monitor, Air Bag

CAUTION:

When servicing the air bag diagnostic monitor (14B056)... The Diagnosis and Testing portion of this section is written to give safety first priority.

Removal

1. WARNING: THE ELECTRICAL CIRCUIT NECESSARY FOR SYSTEM DEPLOYMENT IS POWERED DIRECTLY FROM THE BATTERY AND BACKUP POWER SUPPLY. TO AVOID ACCIDENTAL DEPLOYMENT AND POSSIBLE PERSONAL INJURY, THE POSITIVE BATTERY CABLE MUST BE DISCONNECTED FOR ONE MINUTE PRIOR TO SERVICING OR REPLACING ANY SYSTEM COMPONENTS.

Note:

When the battery is disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module (PCM) (12A650) relearns its adaptive strategy. The vehicle may need to be driven 16 km (10 miles) or more to relearn the strategy.

Disconnect battery positive cable and wait one minute for backup power supply energy to be depleted.

2. Locate air bag diagnostic monitor (light blue, wrapped in black foam, above the gas pedal) and disconnect the two connectors.

3. Depress tabs retaining air bag diagnostic monitor to air bag monitor bracket (14B058). Slide air bag diagnostic monitor off air bag monitor bracket.

4. Disconnect electrical wiring connectors to air bag diagnostic monitor. Remove air bag diagnostic monitor.

Installation

1. Follow removal procedures in reverse order.

2. Run system prove-out check.

The Airbag Diagnostic Module (ADM) is light blue, wrapped in black foam, above the gas pedal

Air Bag Diagnostic Monitor Location diagram.

Item Part Number Description

1 — To Headlamp Switch

2 — To Fuse Box

3 14A282 Retainer Assembly

4 N606678-S39 *****

5 — Connector (Part of 12A581)

6 — Connector (Part of 14A504)

7 13A506 Locator, Position in Hole Provided

8 — To Park Signal Lamp Switch

9 — To Multi-Function Switch

10 — To Stoplight Switch

11 — Clip (Part of 14401)

12 — E4OD Pigtail (Part of 14401)

13 — To Ignition Switch and Steering Column Wiring

14 — To 14405

15 — To Starter Switch Clutch Interlock

16 — Take-Out to Shift on the Fly Switch and Electric Defrost Switch (Part of 14401)

17 — To Warning Buzzer Chime

18 — Remote Keyless Entry Programming Connector

19 15K602 Remote Keyless Entry Module

20 — Air Bag Module

21 14A163 Retainer Assembly

22 — To Trailer Brake Controller

23 14A099 Shield

24 — Vacuum Hose Clip (Part of Vacuum Harness)

25 — Ashtray Wiring (Part of 13726)

26 15A044 Cigar Lighter

27 — PSOM Test Circuit (Part of 14401)

28 — To Bowden Cable

29 18813 Radio Antenna

30 — Brake Anti-Lock Module Test Circuit (Part of 14401)

31 — To 14630

32 — To 14B095

33 — To 18A586

34 — To Right Courtesy Lamp Switch

35 — To Inertia Switch

36 14463 To Ground

37 — To Clearance Lamp F-Series Only for Continuation

38 — Wiper Control Module

39 2C018 Rear Brake Anti-Lock Module (F-150, F-250, F-350 Only)

40 — To Glove Box Lamp

41 — To Heater Mode Switch

42 — To A/C Illumination

43 — To A/C Blower Switch

44 — To Power Point

45 — To Radio

46 18B849 Premium Sound Amplifier

47 14B166 Shift on the Fly Switch

48 — To 14A262 Electric Defrost (Bronco Only)

49 14401 Wiring Assembly

50 — To Cluster (Plug A)

51 — To PSOM

52 — To Cluster (Plug B)

53 14B155 Cap

54 04320 Instrument Panel

55 9A050 Dual Fuel Tank Switch (F-Series Only)

56 14529 Rear Window Control Switch (Bronco Only)

57 — Demister Hose

58 — To Glove Box Lamp

airbagmodule20location.gif

 
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