Holden Vectra Pricing and Specs

Folding metal convertible roofs are a pretty complex piece of gear, and there’s a lot that can go wrong with them. Often, however, it can be a really simple fix.

These folding tops feature lots of interlocks that will prevent the roof opening if the car thinks there’s something amiss. That could be something like a switch that prevents opening if the windows haven’t wound themselves down a few millimetres for clearance. In some cars there’s also a switch that tells the car if the main clasp has been unfastened, and in some cases there’s another that reports back to the car that the hand-brake is, indeed, applied and it’s safe to begin lowering the roof.

These protocols and protections vary from car to car, but in the case of, say, the park-brake switch. The problem can be as simple as a sticky switch in the park-brake assembly that is not triggering. And without that tiny piece of information, the car will decide it’s not safe to open the roof. Check the dashboard to see if the park-brake warning light illuminates when you apply the brake.

So start with all those little switches and clips and make sure the correct information is getting to the computer. If that doesn’t throw up a solution, you need to start investigating things like the electric motor and solenoids that physically operate the roof.

You haven’t given me much to go on here, Rebecca. There are plenty of warning lights on a dashboard these days, and even a 2005 model will have a variety of lights that illuminate to tell you something’s not right.

There are also a host of reasons for the car not starting, so it’s all a bit hit and miss at this stage. To gain a better idea of what’s happening, you could grab the owner’s manual and try to identify what symbol has lit up and which of the car’s systems it represents. From there, you can start to narrow down the causes, but an electronic scan of the car at a workshop sounds like a pretty wise investment. The warning light might even be a by-product of the engine’s refusal to start, and may go out when the engine is finally running.

I’d check both the throttle body, which could need a clean, and the throttle-position sensor (TPS) which can fail or send incorrect information back to the computer. Both these components have a major effect on how a car idles and both can require maintenance or even replacement. Other possible causes could be worn fuel-injectors, a vacuum leak and a huge range of other possibilities. But those are the two I’d investigate first. Once I’d had the car scanned for fault codes, that is.