2004 Chevrolet Trailblazer Liftgate Lock Cylinder Replacement Cost

A liftgate lock cylinder is the mechanism where the key is inserted in order to lock or unlock the liftgate on a car, van, or SUV. The lock cylinder connects by way of rods and cables to the lock and latch assembly that holds the liftgate closed. The cylinder will also actuate the central locking system of the vehicle, and maybe even the liftgate power window, if so equipped.

The liftgate lock cylinder is "coded" to the vehicle's key and it turns when the key is inserted and rotated, just like any other lock. But inside the liftgate, the lock cylinder is separate from the lock. It either moves a rod connected to the lock and latch assembly, or it triggers an electric motor that operates the lock. Usually, a single turn of the key will lock or unlock the liftgate, and a double turn slightly in one direction or the other will lock or unlock the whole vehicle. On some vehicles, holding the key all the way for a time will trigger the power window motor to lower the liftgate glass.

Most often, the symptom of a faulty liftgate lock cylinder is that the key will not turn or will not even insert into the hole at all. Sometimes the key gets stuck in one position or another, or it is difficult to remove. Occasionally a key is broken off inside the lock cylinder and cannot be removed. Electrical problems with the locking system or the power window are likely caused by the failure of other components.

Because most vehicles today that feature a liftgate also have electrically actuated locks and latches, a faulty lock cylinder may not be a big deal. A simple push of a button on a key fob will unlock the vehicle. No key needed. But sometimes, the lock cylinder is not the problem. Symptoms of a bad cylinder may also be related to a bad lock and latch assembly. If the lock mechanism is seized due to damage or corrosion, the key may not turn. In this case, the liftgate may cease to unlock or open at all and require a much more difficult and expensive repair. A vehicle can certainly be driven with a bad lock cylinder, but the problem should not be ignored for long in case the cylinder is not at fault.

The lock cylinders on a vehicle are designed to last the lifetime of the vehicle. But, because today's vehicles are more often locked and unlocked with a remote key fob, with the lock buttons on the door panel, or automatically when shifting into gear, the lock cylinder gets little to no use. This state of disuse often causes a lock cylinder to seize up. The tiny tumblers inside the cylinder can no longer move freely and respond to the key. Most complaints about faulty lock cylinders are caused by this situation.

To diagnose a bad liftgate lock cylinder, a technician will attempt to insert and turn the key. If the key is difficult to insert or does not turn freely, the technician may try to lubricate the cylinder and get it to free up. If this is not possible, the technician may remove the interior trim panel on the liftgate to access the cylinder, the lock and latch assembly, and the connecting linkage (cables and rods). The goal is to rule out any other components as the cause of the problem. The lock cylinder may be disconnected from the linkage to observe how it operates on its own. If the rest of the system is operating properly, the lock cylinder is replaced.

To replace a liftgate lock cylinder, a technician will need to open the liftgate and remove the interior trim panel. Some electrical components mounted in the liftgate may need to be taken out for access. The lock cylinder is disconnected from its linkage. A retaining clip is unseated and the lock cylinder is pulled from the outside. A new lock cylinder needs to be "coded" by the dealer to fit the key before it is installed.

It is easy to neglect the lock cylinders on a vehicle, especially the one in the liftgate. Should the battery die, a key is the only way to unlock the vehicle. RepairPal recommends that the lock cylinders, whether in the liftgate or in the doors, be operated with the key periodically as part of routine vehicle maintenance. This will help to prevent the cylinders from seizing up and failing prematurely.

A lock cylinder that seems to be faulty should not be ignored. If the symptoms are related instead to a faulty lock and latch mechanism, repairs could be much more complex.

The lock cylinder inside the liftgate on some vehicles is difficult to access. The interior trim panel may also be tricky to remove without breaking fasteners or mounting flanges. In many cases, the repair can be done by someone with intermediate DIY experience. However, the procedure is often performed "blind," as the technician cannot see inside the liftgate to identify the components. Instead it is necessary to work by feel alone or with the aid of mirrors and a good repair procedure source, such as an online manual.