This era of Australin Fords had a bit of a habit of having their body computers go on the blink. When that happened, a whole bunch of things could start acting up, but the central locking was a prime suspect.

When a car thinks it has a door, bonnet or bootlid opened, it will often refuse to lock, preferring instead to warn the driver that the car is not secure. And when the body computer is confused, it can interpret a closed door as an open one. But before you take it to an auto electrician to be sorted, try this: Take a can of lubricating spray and apply some to the little door sensor inside the door jamb. This is the micro switch that tells the computer what’s going on, and if the switch is full of dust or jammed, that won’t happen. Sometimes freeing the switch will make the problem go away.

The other thing to try is to disconnect the car’s battery and leave it overnight before reconnecting it. Sometimes this will actually reset the body computer. It doesn’t work every time, but sometimes it will do the trick.

It might be a case of super-fast overheating, but one would expect the temperature needle to take more than 15 seconds to go from normal to dangerously hot. You could have a broken or faulty gauge, a short-circuiting wire somewhere in the gauge’s wiring or even a temperature sender unit that is giving false readings to the gauge once it gets to a certain temperature.

The first thing to do is work out just how hot the engine really is getting. You can do this with an external temperature gauge or an infra-red thermometer that can be bought for a few dollars. Aim the infra-red beam at the top tank of the radiator, or the top radiator hose and see what reading you get. You should see a value of between 85 and 95 degrees Celsius. At which point, the engine wouldn’t appear to be overheating (provided your new thermostat is working properly).

By the way, the coolant being under pressure when the engine is at operating temperature is perfectly normal. It’s why you shouldn’t remove the cap on the expansion tank when the engine is hot as you can easily get burnt by the escaping coolant. Modern engines pressurise their cooling systems to actually raise the boiling point of the coolant and make their cooling systems more efficient.

The Territory has a yellow check-engine light just on the outside of the tachometer’s face, around the 2000rpm mark. Perhaps that’s what you saw flickering on. This is probably nothing to worry about as the light immediately switched itself off, suggesting that whatever the problem was, it was a fleeting one.

This light is linked to the car’s onboard diagnostic system which monitors the entire car for faults and then logs them for future problem-shooting. If a problem occurs twice within a certain time-frame, then the check-engine light must illuminate to warn the driver to have the car checked and the problem fixed.

If the light reappears and stay lit up, then you need to act to have the problem found and fixed before it has the chance to do any permanent damage to the car’s driveline. As a side-note, a car with an illuminated check-engine light is technically unroadworthy.