Holden Problems

The three brake lights are almost certain to be on the same circuit, meaning that if two are working, the third one is likely to be suffering from something as simple as a blown globe. Perhaps the globe is loose in its socket, but if two out of three are working, then you probably don’t have an issue with the wiring or fuses.

The wiper issue could be to do with the body computer (which controls a huge number of a modern car’s functions) but, equally, could be something as simple as dirty contacts in the switch part of the stalk that controls the wipers. Some contact-cleaning spray into the switch might do the trick.

All the V6 Commodores from this era used much the same automatic transmission, a four-speed unit. While most of these units were identical, there were some detail differences across the years, so make sure you get the transmission with the correct number of electrical pins to be compatible with the wiring loom in your car.

It shouldn’t matter whether the replacement transmission came from a car with a floor-shift; it should still hook up to your column shift mechanism with no problems. You might have to swap a few bits and pieces involved in the shifter mechanism to mate it all, but you’ll be able to make it work.

No, there was only one automatic gearbox, a six-speed unit that was vastly more popular than the other choice, a six-speed manual. For the 2017 model year, Holden upgraded the automatic transmission with what’s called a centrifugal pendulum absorber torque converter.

This absorber was a type of dampener designed to reduce vibrations form within the torque converter and improve the driveline’s smoothness. But this was applied to all 2017 Colorado diesels, meaning the transmission differs from a 2016 or earlier unit.

The gasket in question is probably the head gasket and when this fails, it can allow the engine oil and coolant to mix, which is why you’re seeing oil in the coolant expansion tank. If you check the engine’s oil dipstick, you may find that coolant has found its way into the sump, mixing with the oil as well, giving the latter a milky quality rather than appearing clear and clean.

This would have been a potential warranty claim back when the car was new, but at 11 years of age – even with your low mileage – it would be a miracle if Holden agreed to fix it as part of a warranty job.

The filling point for this transmission is on top of the gearbox, under the ECU (drive-line computer). So, to access it, you’ll need to move the computer (which attaches to the battery tray) out of the way. Take lots of photos before removing bits and pieces so you’ll know how it all goes back together.

However, it’s doubtful that a lack of gearbox oil is your problem here. If the oil was low, the transmission would probably be making some seriously bad noises or would be completely seized up, not just refusing to shift out of reverse. The refusal to abandon reverse probably has more to do with a mechanical selector problem. But don’t rule out a worn or maladjusted clutch, either.

The coincidental nature of these faults would make most mechanics suspect the body computer is having a nervous breakdown. This computer is the one that controls functions ranging from central locking, the immobiliser, power windows, dashboard and even the entertainment system. It’s also responsible for the indicators, climate control and probably the gear selector. See the pattern?

And because the computer itself – rather than an individual component – has gone on the blink, it won’t always throw an error code. An auto electrician is the first place to visit as your diagnosis of an electrical fault is almost certainly spot on. Don’t rule out a simple bad earth connection, either, as these can also cause electronic havoc.

The thing with problems like these is that you could be looking at a single fault or a group of problems that are each giving you a different symptom. Something could be getting hot in the engine management system that is causing the vehicle to shut down, and a good place to start looking would be the crank-angle sensor. When these get hot, they stop sending a critical signal to the engine’s computer and it just shuts down. After a short cool-down period, the sensor can often come back to life and away you go again.

Meantime, a stuttering idle and inconsistent engine speed on start-up would make a lot of mechanics check out the stepper motor which is part of the throttle mechanism and is responsible for setting the idle speed and allowing the engine to start.

Has your mechanic scanned the car or simply done a few basic checks? An electronic scan should be your next step if it hasn’t already been done.

A manifold leak will throw the engine’s fuel-air ratio out the window and can cause poor cold running and hard starting. The old school way of checking for a vacuum leak is to get the engine idling and then spray either carburettor cleaner (or something else flammable) around the intake area of the engine. If the engine suddenly picks up revs, you almost certainly have a vacuum leak. But be careful, spraying flammable stuff around a running engine comes with a fire risk.

The other thing to check would be the throttle body and the sensor attached to it that tells the computer how much throttle has been applied. Again, these can start to give false readings, throwing the fuel-air mixture out.

Before you do either of those things (replace the engine or the whole car) find out where the coolant is leaking from. You might find that it’s a simple case of a leaking hose or a worn out water pump that is causing the leak. If that’s the case, it could be fixed for a few hundred dollars or perhaps even less. Even if the problem is a rotted welch plug or a blown head gasket, the cost to fix it won’t be anywhere near as high as replacing the engine.

On top of that, you know the history of the engine you have, while a second-hand engine can be a bit of a lucky-dip: You might get a good one, you might not.

Based purely on your symptoms, a broken clutch is the most likely cause. When a clutch loses the ability to fully disengage the engine from the transmission (through either wear or damage) the gears can become very difficult to select. Sometimes they will engage with a crunch, at other times you may not be able to select them at all.

This is a different problem to a worn clutch which has lost its clamping ability and is slipping, but the ultimate fix is the same: A new clutch assembly.