When do parking brake cables need replacing?

An emergency or parking brake is a vital safety feature; when engaged, the parking brake activates both rear brakes. In some modern cars, the parking brake is engaged by a button (electronic parking brake); in others, by manually pulling the lever or pressing the parking brake pedal.
Parking brake system and cables Parking brake cables. See more illustrations: Fig1, Fig2, Fig3.
In cars with a manual parking brake, the lever or the pedal is connected to the rear brakes via parking brake cables. The cables run from the pedal or lever, through the floor and then underneath the car to both rear brakes. Because of the location, rear parking brake cables tend to rust, seize up or break. Other problems with cables include stretching, fraying and wearing out.

What are the signs of a worn or sticking parking brake cable? If the cable is seized or worn out, the parking brake may stop working and cause the vehicle to roll on an incline with the parking brake engaged. In other cases, a sticky brake cable may not release fully, causing one or both rear brakes to be partially engaged and "drag" or even overheat while driving. When parking brakes are not fully released, it feels like the vehicle is not rolling freely. In some cases you might notice squeaking noises from one or both rear brakes when driving. The rear wheel where the parking brake is not released fully may also appear excessively hot. The parking brake handle or pedal may also appear too tight or too loose when operated.
A properly working parking brake must engage with a few clicks of the lever or pedal and release fully when the pedal or lever is released. The number of clicks is usually listed in the inspection procedure in the factory service manual for technicians. For example, the service manual for the Toyota FJ Cruiser specifies 5 to 7 clicks.

Is it safe to drive with bad parking brake cables? No, the parking or emergency brake is a mandatory safety feature and if it doesn't work properly, the vehicle is considered unsafe. A faulty parking brake will cause the vehicle to fail a state (safety) inspection. If the parking brake cables or other parts of the parking brake mechanism are bad, they must be replaced.

How can you check parking brake cables? Typically, mechanics check the parking brake operation during regular services that include a brake inspection. In some shops, a simple oil change might not include testing of the parking brake; in this case, you can ask a mechanic to check it separately. Often the damage to a parking brake cable is visible.
Damaged parking brake cables In this truck, the parking brake cable was rusted inside and sticking due to jacket damage.
Parts of the cables (conduits) are protected by the PVC jacket. When the PVC jacket is damaged, water gets inside the cable and causes it to rust and seize up. If the cable is sticking, but not otherwise damaged, freeing and lubricating it might be enough. The parking brake operation must be properly tested after repairs.

How much does it cost to replace parking brake cables? Parking brake cables for both rear wheels are typically replaced at the same time. In some cars, cables come as two separate parts, in others, as one kit with all the brackets and cables. In an average car, replacing both rear parking brake cables costs from $320 to $480. In vehicles with rust damage, more parts may need to be replaced. After the cables are replaced, the parking brake must be adjusted and tested. Replacing parking brake cables is not very difficult, but it requires good access to the vehicle from underneath. In some cars, the rear drum or parking brakes must be taken apart to get access to parking brake cables.

Do parking brake cables need any maintenance or adjustment? Yes, some cars have self-adjusting parking brakes, but in others, the parking brake might need to be adjusted if the cables are stretched, but otherwise in good shape. In most cars, the parking brake mechanism is adjusted at the equalizer or at the lever (pedal). Typically the parking brake is adjusted when the brakes are serviced or replaced. In addition, some of the parts of the parking brake system might need to be cleaned and lubricated.