Active Head Restraints Deploy Without Warning

This post originally appeared on dodgeproblems.com

The active head restrains (AHR) in some Chrysler vehicles are unexpectedly striking occupants in the back of the head. Granted, the systems are designed to push the head restraint forward to prevent whiplash and other neck injuries, but they're supposed to wait for a rear-end collision first. The constant threat of random concussion is, unsurprisingly, making owners a little nervous.

What Causes Chrysler's AHR to Randomly Deploy? ∞

Unlike most car problems these days, this isn't some software bug or electrical over stress. Just good ole' fashioned corner cutting and mechanical failure.

Chrysler has been using AHR systems manufactured by a company called Grammer AG. The restraints are split into front and back pieces sandwiched around compressed springs.

The front padded section has an internal bracket, called a “sled”, that holds a metal striker pin. The pin then snaps into two hooks located in the rear section that are wired up to some sensors.

If the sensors detect a rear-end collision, the hooks release the pin and the whole front-padded section pushes forward quickly on the sled to help cradle your neck before it violently snaps back.

Cheap plastic parts ∞

This system breaks down where the sled holds the striker pin. Grammer AG made their sleds out of a cheap plastic polymer that often cracks because for a few reasons:

1. It's really only two little pieces of non-reinforced plastic holding the striker pin in place.
2. The plastic doesn't handle the estimated 75 pounds of constant internal pressure very well, and often cracks along weak points.
3. The plastic seems to have a negative reaction with the chemical coating on the striker pin.

All this adds up to the plastic cracking or splitting, at which point the striker pin releases and occupants are left wondering why they just got sucker-punched to the top of their spine.

A supplier problem ∞

Grammer AG also supplies AHR to Mercedes-Benz for their NECK-PRO system. And guess what? Those suffer from the same problem.

It's almost like plastic wasn't the best choice for durability under pressure 🙄.

The Costs of AHR Deployments ∞

Random AHR deployments are a headache in every sense of the word.

There's the physical cost and scary tales of owners who say they were left disoriented or in pain, some with continued nausea related to concussions.

Then there's the financial cost of resetting or replacing the AHR, depending on the condition of the sled. The average repair cost is over $800 per head restraint. And it's not always something owners have success getting covered under warranty.

AHR Investigation ∞

In November of 2019 the National Highway Traffic Safety Administration (NHTSA) opened an investigation into random AHR deployments, but only in the 2014 Dodge Durango and Jeep Grand Cherokee ... not any Chrysler vehicles.

In its preliminary evaluation^[1] they stated it appears a plastic material inside the AHR, intended to hold the AHR in the "ready" (compressed) state, fails due to stress and/or fatigue allowing the AHR to actuate unexpectedly.

Of the 128 complaints, 13 resulted in injuries and occurred at either (or both) front seat positions, when the vehicle is either occupied or unoccupied, when the seat is either occupied or unoccupied, and in some cases (nearly two-thirds) while the vehicle was in motion. In other words, randomly.

Durango AHR Warranty Extension ∞

While the investigation was still pending, certain Dodge owners were offered a warranty extension^[2] in service bulletin #23-018-20 REV. C.

The warranty extended to 10 years and unlimited mileage to replace AHRs that have been deployed with broken and failed sled brackets.

But it's not just a Durango problem. Or just a Dodge problem.