The Mk7 Fiesta is a very nice car, but it has some minor design flaws. One common problem is the hatchback release button. It is located directly below the rear wiper, which operates through a hole in the tailgate. Unfortunately this hole lets in water and muck, which then runs down and collects around the switch. Eventually water makes its way in and corrodes the contacts.
Symptoms of this can be confusing. In the case of my wife’s car it started releasing the tailgate every time you started the engine. or sometimes when it stopped. I’m not sure if this was a short caused by the vibration or a voltage issue, but repairing the switch cured it either way.
The first step is to remove the faulty switch. I actually found a guide on the internet that told people to strip the inside trim from the tailgate and remove the wiper motor to access it. Don’t do this, it’s just plain silly! The switch clips in from the outside, and can be easily pried out. It’s best to do it with the tailgate open, as everything is at eye level. Removing the number plate may help, as it’s a tight fit. I managed without. Use something wide and thin to prise it out, working at one side then the other in small steps, taking care not to scratch the paintwork.
This picture shows the location after the switch has been removed and unplugged. The plug was nice and clean inside, which was a relief. As you can see by all the gathered dirt, there was a lot of mess around the switch.
The switch is in two halves, held together by six small phillips screws. Undo these and inspect it. Mine was wet, and the both springs were corroded, one broke in half as I opened the switch. If it isn’t too badly damaged then you can dry it out, give it a good clean with an electrical cleaning spray, followed by a quick squirt of WD-40 to prevent future water penetration.
If the switch is badly damaged, like mine was (it still works after repair, but doesn’t feel right when you use it) then it’s probably best to order a replacement. The part number is shown below:
The code on mine was 6M51-19B514-AC
The two letters at the end are a revision code, so may vary depending on the age of the car. The part number and switch is also shared with the Mk2 Focus, C-Max and Mk3 Mondeo, so if you want a cheap repair then you may be able to find one at a breaker’s yard. The new switch isn’t expensive. At the time of writing it cost about £34 inc VAT and delivery from this Ford Dealership, or can be found new or used on.