Mazda BT-50 Problems

There’s a very simple check you can do to see whether the battery or the charging system (alternator, regulator and wiring) is at fault here. With the engine running, place the probes of a multi-meter (switched to measure voltage) on the relevant battery terminals. If you see a figure of anywhere between 13.2 and 14.7 volts, the charging system is doing its job. You might need to rev the engine slightly off idle to see these numbers, but the voltage going into the battery should be in that range.

At this point, the battery becomes the main suspect, and a worn out battery will often neither hold a charge nor accept one.

There have, indeed, been issues with this transmission with Mazda authorising a service bulletin to attend to some vehicles. However, it‘s generally thought that affected vehicles were built between 2011 and 2014, after which point, the problems were fixed. Which is not to say your 2015-built car doesn’t have the same problems.

The best way to proceed is to ignore the dealerships and go straight to Mazda Australia’s customer service department. Unfortunately, your car is now 10-years-old and well and truly outside its warranty, but I agree that 120,000km is not an acceptable lifespan for a component such as a modern automatic transmission to fail.

The last decade of dual-cab four-wheel-drive utes have emerged as the tow-vehicles of choice, and you see them everywhere filling roles exactly like the one you have planned. Popular models include the Ford Ranger you’ve nominated, Toyota HiLux, Mazda BT-50, VW Amarok, Mitsubishi Triton, Nissan Navara and Isuzu D-Max. But there are also cheaper alternatives including makes like the South-Korean made Ssangyong and various Chinese brands like LDV and Great Wall.

Just make sure you know exactly how much you need to tow before making a decision as some of the cheaper models don’t have the same outright towing capacity and even if they do, some of them don’t have the engine performance to make towing as easy as it should be. For parts availability, the Toyota would be king in really remote areas, but any of the major brands are pretty well covered in Australia.

Meantime, don’t rule out ute-based wagons such as the Ford Everest, Isuzu MU-X, Mitsubishi Pajero Sport and Toyota Fortuna. These offer better ride comfort when unladen thanks to more sophisticated rear suspensions and most have as much or almost as much towing capacity as their ute brethren.

The fact that the fuel economy average seems to be creeping up can have a lot to do with the fact that you’re becoming more familiar with the vehicle and using more throttle as a result. But remember, too, that until you reset the average on the trip computer, what you’re seeing is the full history of your consumption from when the trip computer was last zeroed, not just the most recent trip you’ve done.

It's true that engines often start to use a little less fuel as they 'bed in’ after a few thousand kilometres. And for a modern turbo-diesel like yours, I reckon 10,000km or even 15,000km might be the magic number. However, don’t be too disappointed if it doesn’t come down a whole lot. I reckon for that vehicle, driven the way you’ve described, 10 or 11 litres per 100km isn’t a bad average to aim for.

Other factors play a big part, too. Does the vehicle have a bull-bar or roof racks? Both these add weight and aerodynamic drag respectively, and can easily make the car consume more fuel. A roof rack at 100km/h can be worth an extra litre per 100km.

A lot of modern transmissions don’t have a dipstick at all, particularly as manufacturers move towards transmissions that have very long service intervals and are considered sealed systems. Which is fine until it’s not. And that’s when you need to check the level and condition of the transmission fluid.

The good news is that the BT-50 in question does have a dipstick. The bad news is that’s mighty difficult to get to. You need to be under the car (so safety is the key here) and then locate a 19mm fitting on the driver’s side of the transmission. By unscrewing this fitting, you can withdraw the dipstick and check the level. The other catch is that you need to do this with the engine running (to get an accurate reading) and the dipstick is located close to what will therefore be a hot exhaust system.

All of this means it’s really a job for a specialist with a hoist and is a great example of a carmaker saving a few cents per car in production at the expense of the greater running costs for the owner over the life of the vehicle.

There are many reasons for a vehicle to enter limp-home mode. One of them, of course is transmission temperature, but there are lots of things being monitored, from the temperature of the engine oil, coolant temperature, oil level and even the operating temperature of the EGR valve (which is often water-cooled in vehicles like the Mazda).

The point being that even though the transmission entered limp-home mode, the actual problem may have been elsewhere, but the vehicle’s computer believed that shutting down much of the transmission’s functions would preserve and protect the rest of the driveline. Don’t forget, either, that there are many things – a failed solenoid, low fluid level, even a faulty wiring connection or earth – that can cause a transmission limp-home event beyond actual overheating.

You should be guided by your mechanic’s quote for either outcome. In some cases, solenoids are relatively cheap to buy and don’t require too much labour to replace. But, depending on the vehicle, they can also be very expensive and require more or less a full transmission strip-down to remove and replace.

You also need to assess the condition of the whole transmission as putting new parts into a worn gearbox will only delay the inevitable.

The smart money here suggests that there’s something your car’s electrical system and body computer don’t like about replacement LED lights. That’s assuming you’ve installed them correctly, of course. The first thing you should do is replace the standard globes and see if that restores the lights’ operation. If it does, you can be reasonably sure there’s a problem with the way the car reacts to the LED replacements.

Not all cars appreciate the conversion to LEDs. These newer lights draw a lot less current than conventional globes and, while that sounds like a good thing, the lack of current-draw detected by the body computer can cause problems. Another common problem with LEDs is that the low current-draw makes the car’s computer think that there’s a blown globe at which point it can trigger a warning light on the dashboard.