Airbag control unit with part number AB39-14B321-AK

What does the airbag control unit AB39-14B321-AK do?

The airbag control unit AB39-14B321-AK is the central control unit of the restraint system (SRS) for Ford. It evaluates the signals from the crash sensors, decides within milliseconds in an accident which airbags and seatbelt pretensioners are triggered, and monitors the system continuously. It reports faults via the airbag warning light.

The sensors deliver measured values continuously, which the unit compares with one another. Seatbelt pretensioners and airbags may only ignite when an impact has actually occurred, which is why the evaluation is so fast. As a result, the system is ready for use without delay in an accident.

After an accident the unit stores crash data and locks itself.

Why does the control unit AB39-14B321-AK fail?

The most common causes are crash data stored after an accident, even if no airbag has been triggered; a normal diagnostic tool cannot erase it. Other causes include aged electronics, cold solder joints, moisture and corrosion, and voltage spikes.

The other causes in detail:

• Aged electronic components
• Cold solder joints
• Moisture and corrosion at plug connections
• Voltage spikes, for example from a weak battery or a jump start

Which of these points applies in an individual case becomes clear only when the unit is examined. Until then, all the possibilities mentioned remain open.

How can you tell that the AB39-14B321-AK is defective?

A defect shows up as the airbag warning light in the instrument cluster, which stays on permanently or intermittently. It is accompanied by a fault message in the instrument cluster, a diagnostic tool that cannot connect to the unit, or a fault memory that cannot be cleared.

These signs are noticeable:

• Airbag warning light stays on permanently or intermittently
• Fault message in the instrument cluster
• Diagnostic tool gets no connection to the control unit
• Fault memory cannot be cleared

The warning light is the most important visible sign. In an emergency, the airbags and seatbelt pretensioners may fail to deploy if the system is disrupted. Please take the indication seriously.

Which vehicles is the AB39-14B321-AK fitted in?

The control unit AB39-14B321-AK is fitted in these vehicles: Ford Ranger 3 (2011-2015), 3 1st Facelift (2016-2019) and 3 2nd Facelift (2019-2023). The assignment refers to this part number.

The list shows the assigned vehicles at a glance:

• Ford Ranger 3 (2011-2015)
• Ford Ranger 3 1st Facelift (2016-2019)
• Ford Ranger 3 2nd Facelift (2019-2023)

Compare the part number on the label of the removed unit with this page; this only ensures that it is the right unit. In addition, have the fault memory read out before removal, because only the result shows whether the control unit itself is defective or whether a plug or cable is affected.

For the same vehicles, we also repair control units with the part numbers AB3914B321CF, KB3T-14B321-BD.

How does the repair of the AB39-14B321-AK work?

For control unit AB39-14B321-AK, first have the fault memory read out and enclose the log, then disconnect the battery and only then remove the unit. Afterwards create a repair order online and send the control unit off well packed. Processing at Airbag24 usually takes 3–4 working days.

At Airbag24 the unit is examined on the test bench, defective components are repaired and stored crash data is erased before a function test follows. The function test decides whether the unit is fully ready for use. Afterwards your own unit 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 AB39-14B321-AK get to Airbag24?

You send the control unit AB39-14B321-AK as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 returns the unit by UPS.

The printed repair order goes into the parcel, and you pack the control unit shock-proof. The packaging protects the control unit on its way.