air bag
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air bag
94 bronco 351 auto...just started get air bag code 45...ive found that its the >center radiator crash sensor not mounted properly<.. (bad ground???) looked arround but not knowing what im looking for i cant seem to find it ...anyone know just were it is and what it looks like....thanks
Posting Guru
Joined: Mar 2002
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From: Willamette Valley, Oregon
It would be your Left Front sensor in question or possibly your diagnostic monitor. Make sure and disconnect your positive battery cable for atleast 5 minutes before checking anything out in your airbag system. Here are the pinpoint tests from the 94 Fseries/Bronco manual on CD.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
Normal Operation
The air bag diagnostic monitor measures the resistance between Pin 21 (Circuit 620, P/LB) and Pin 3 (diagnostic monitor reference ground). If the air bag diagnostic monitor measures a difference of more than 2.0 ohms between Pin 21 and Pin 3, it will flash out Code 45.
Note that Circuit 620 (P/LB) is attached to the side casing of the LH front air bag sensor and bracket. In addition, the case is grounded to the vehicle.
Possible Causes
High resistance on Pin 21 (Circuit 620, P/LB) to ground can be caused by:
1. A poor connection due to loose mounting, dirt, or corrosion at the mounting location of the LH front air bag sensor and bracket.
2. An open or damaged wire in Circuit 620 (P/LB) from Pin 21 of the diagnostic monitor harness connector to radiator support LH front air bag sensor and bracket. This includes splices and in-line connectors.
3. NOTE: Circuit 620 (P/LB) passes through an in-line connector between the main instrument panel harness and the engine compartment harness that connects to the LH front air bag sensor and bracket.
An open wire or loose (Circuit 620 P/LB) wire attachment inside radiator support LH front air bag sensor and bracket.
l Check splice and in-line connectors for poor crimps, etc.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-1 CHECK FOR DTC 45
l Turn ignition switch lock cylinder to ON.
l Count diagnostic trouble code (if any).
l Is Code 45 flashing?
Yes
GO to «45-2».
No
READ the normal operation description for this diagnostic trouble code. EXAMINE the diagnostic trouble code schematic and LOOK for areas where intermittent problems would occur (connectors, splices, crimps, etc.). DO NOT PROCEED with pinpoint tests until the code is flashing! Failure to do so will result in needless replacement of the air bag diagnostic monitor and repeat service.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-2 DEACTIVATE SYSTEM
l Deactivate system (leave positive battery cable disconnected).
l Disconnect air bag diagnostic monitor
l Set ohmmeter on the lowest ohm scale possible (200 ohms).
l Zero ohmmeter. Record resistance reading with the two leads together.
l Measure the resistance between Pin 21 and Pin 3 (ground).
l Is the resistance greater than 2 ohms?
Yes
GO to «45-3».
No
REPLACE air bag diagnostic monitor. RECONNECT system. VERIFY system. REACTIVATE system.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-3 CHECK RADIATOR SUPPORT LH FRONT AIR BAG SENSOR AND BRACKET GROUND
l Disconnect the LH front air bag sensor and bracket from the harness.
l Measure the resistance between the P/LB "ground" wire in the sensor connector and a nearby, "good", chassis ground (be sure that this ground is clean and bare.)
l Is the resistance less than 2 ohms?
Yes
INSPECT circuit between Pin 21 and the LH front air bag sensor and bracket. CHECK all interconnects and splices for poor connections. SERVICE any poor connections. RECONNECT system. VERIFY system. REACTIVATE system.
No
REMOVE screws retaining sensor. CLEAN mounting surface of sensor and chassis. REMOUNT sensor. TIGHTEN screws to 10-14 N-m (8-10 lb-ft).
GO to «45-4».
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-4 MEASURE RESISTANCE OF SENSOR TO GROUND
l Measure the resistance between the P/LB "ground" wire in the sensor connector and the chassis ground.
l Is the resistance less than 2 ohms?
Yes
RECONNECT system. VERIFY system. REACTIVATE system.
No
REPLACE LH front air bag sensor and bracket. RECONNECT system. VERIFY system. REACTIVATE system.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
Normal Operation
The air bag diagnostic monitor measures the resistance between Pin 21 (Circuit 620, P/LB) and Pin 3 (diagnostic monitor reference ground). If the air bag diagnostic monitor measures a difference of more than 2.0 ohms between Pin 21 and Pin 3, it will flash out Code 45.
Note that Circuit 620 (P/LB) is attached to the side casing of the LH front air bag sensor and bracket. In addition, the case is grounded to the vehicle.
Possible Causes
High resistance on Pin 21 (Circuit 620, P/LB) to ground can be caused by:
1. A poor connection due to loose mounting, dirt, or corrosion at the mounting location of the LH front air bag sensor and bracket.
2. An open or damaged wire in Circuit 620 (P/LB) from Pin 21 of the diagnostic monitor harness connector to radiator support LH front air bag sensor and bracket. This includes splices and in-line connectors.
3. NOTE: Circuit 620 (P/LB) passes through an in-line connector between the main instrument panel harness and the engine compartment harness that connects to the LH front air bag sensor and bracket.
An open wire or loose (Circuit 620 P/LB) wire attachment inside radiator support LH front air bag sensor and bracket.
l Check splice and in-line connectors for poor crimps, etc.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-1 CHECK FOR DTC 45
l Turn ignition switch lock cylinder to ON.
l Count diagnostic trouble code (if any).
l Is Code 45 flashing?
Yes
GO to «45-2».
No
READ the normal operation description for this diagnostic trouble code. EXAMINE the diagnostic trouble code schematic and LOOK for areas where intermittent problems would occur (connectors, splices, crimps, etc.). DO NOT PROCEED with pinpoint tests until the code is flashing! Failure to do so will result in needless replacement of the air bag diagnostic monitor and repeat service.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-2 DEACTIVATE SYSTEM
l Deactivate system (leave positive battery cable disconnected).
l Disconnect air bag diagnostic monitor
l Set ohmmeter on the lowest ohm scale possible (200 ohms).
l Zero ohmmeter. Record resistance reading with the two leads together.
l Measure the resistance between Pin 21 and Pin 3 (ground).
l Is the resistance greater than 2 ohms?
Yes
GO to «45-3».
No
REPLACE air bag diagnostic monitor. RECONNECT system. VERIFY system. REACTIVATE system.
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-3 CHECK RADIATOR SUPPORT LH FRONT AIR BAG SENSOR AND BRACKET GROUND
l Disconnect the LH front air bag sensor and bracket from the harness.
l Measure the resistance between the P/LB "ground" wire in the sensor connector and a nearby, "good", chassis ground (be sure that this ground is clean and bare.)
l Is the resistance less than 2 ohms?
Yes
INSPECT circuit between Pin 21 and the LH front air bag sensor and bracket. CHECK all interconnects and splices for poor connections. SERVICE any poor connections. RECONNECT system. VERIFY system. REACTIVATE system.
No
REMOVE screws retaining sensor. CLEAN mounting surface of sensor and chassis. REMOUNT sensor. TIGHTEN screws to 10-14 N-m (8-10 lb-ft).
GO to «45-4».
Pinpoint Tests
PINPOINT TEST DTC 45: LH FRONT AIR BAG SENSOR AND BRACKET NOT MOUNTED TO VEHICLE PROPERLY
45-4 MEASURE RESISTANCE OF SENSOR TO GROUND
l Measure the resistance between the P/LB "ground" wire in the sensor connector and the chassis ground.
l Is the resistance less than 2 ohms?
Yes
RECONNECT system. VERIFY system. REACTIVATE system.
No
REPLACE LH front air bag sensor and bracket. RECONNECT system. VERIFY system. REACTIVATE system.
Last edited by Ponyracer; Oct 14, 2005 at 12:39 AM.
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Junior User
Joined: Jun 2004
Posts: 97
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thanks for the info guys...ill be checking it soon as this rain stops here in ny...am thinking it may be as simple as a bad ground or connector given the location of the sensor and that it only started flashing when we started getting all this heavy rain the past serveral days...thanks again
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