Holden Convertible Range

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.

There are two possibilities here and it will all depend on whether your car is a 2005 model (that was first sold in 2006) or a post-facelift model and also whether it’s a TS Astra or an AH model Astra. If it’s the earlier car, then you might be in luck. The process involves taking the new key, placing it in the ignition and turning the ignition on (without starting the engine). Then, when all the dashboard lights are lit up, you press one of the remote buttons on the key. And that’s about it. You should hear the car lock and then unlock itself to let you know the process is complete and you’re good to go.

For post-2005 models, however, things are not so simple. In this case, you need to either visit a locksmith or a workshop that has the Holden diagnostic gear, as the new key needs to be coded to the car via the diagnostic port. That said, I’d give the first method a try before spending money at a workshop. Who knows, you might just get lucky.

The good news is that this probably isn’t an actual gearbox problem, but rather one with the mechanical linkages that select each gear or perhaps even the gear selector itself. If you can remove the centre console, you might be able to locate the offending (loose) fastener that is allowing the gear lever to flop about and not find its proper place.

If, however, you mean that the vehicle doesn’t want to select Drive properly first thing in the morning and either won’t move or moves very slowly when you accelerate, then you could well be looking at a worn transmission. That said, the same problem can be caused by a transmission that is simply low on fluid, and a top up will put things right. So that’s the first step: Check the owner’s manual for the correct fluid-checking process and try that. If a top-up doesn’t fix it, it’s off to a mechanic. But beware – driving the car in that state could be doing extra damage to the transmission.