Airbag control unit with part number 4L3A14B321DJ

What does the airbag control unit 4L3A14B321DJ do?

The airbag control unit 4L3A14B321DJ is the central control unit of the restraint system (SRS) of Ford. It evaluates the crash sensors, decides in an accident within milliseconds on the triggering of the airbags and seatbelt pretensioners, and monitors the system continuously.

Detected faults are passed on via the airbag warning light in the instrument cluster. The evaluation runs continuously in the background.

After an accident the unit stores crash data, and after that it is locked.

Why does the control unit 4L3A14B321DJ fail?

Stored crash data is the most common cause, namely after an accident, even if no airbag has fired. In addition there are aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes such as from a weak battery or jump-starting.

Crash data cannot be removed with a standard reader. The repair at Airbag24 eliminates it before the function test follows.

The other causes mainly concern the electronics and their connections. Solder joints can break, moisture attacks contacts, and voltage spikes stress the circuitry in the unit.

How can you tell that the 4L3A14B321DJ is defective?

A defect shows up as the airbag warning light staying on permanently or intermittently, as an error message in the instrument cluster, as a lack of connection between the diagnostic tool and the control unit, or as a fault memory that cannot be cleared.

If you notice one of these indications, you must reckon with the airbags and seatbelt pretensioners possibly not deploying in an emergency. The warning light therefore points to a fault in the restraint system, which you should have clarified promptly.

A look at the fault memory reveals which message is present. Even then, the warning light remains the first hint you should watch for.

Which vehicles is the 4L3A14B321DJ fitted in?

The control unit 4L3A14B321DJ is fitted in these vehicles: Ford F-150 11th generation (2004-2008).

The list of the associated vehicles follows.

• Ford F-150 11th generation (2004-2008)

Comparing the part number on the label of the removed unit with this page only confirms that it is the right unit. Whether the control unit is actually defective is shown only by the fault memory read-out. Have it read before removal, because a connector or a cable can also be the cause.

For the same vehicles, we also repair control units with the part numbers 4L3A14B321AH, 6L34-14B321-BA.

How does the repair of the 4L3A14B321DJ work?

First have the fault memory read out and attach the log. Then disconnect the battery and only then remove the control unit. At Airbag24, testing, repair and checking usually take 3–4 working days.

You create the repair order online before sending in the well-packed unit. The sequence protects during removal and therefore applies without exception.

At Airbag24 the unit is examined on the test bench, defective components are replaced, the crash data is erased and a function test is run. The repaired unit, which is your own, then goes back to you.

Our repairs come with 2 years' statutory liability for defects. The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.

How does the control unit 4L3A14B321DJ get to Airbag24?

The unit goes either as a parcel to Airbag24 or, for an extra charge, is collected by UPS. It returns by UPS once the repair is complete. You enclose the printed repair order with the parcel and pack the control unit shock-proof.

A firm carton with enough padding protects the unit against knocks during transit.