Isuzu Problems

This is a tricky one because the D-Max’s SVS warning light seems to be a bit of an all-rounder. That is, it indicates a fault, but a non-specific one. Certainly not one that can be read by the majority of aftermarket scanning tools. Logic suggests there’s something within the driveline that is getting too hot for the computer’s liking, a theory backed up by the fact that it only triggers when you’re towing a big load and the car is working its hardest.

The solution seems to be to present the car at an Isuzu dealership as this may be the only workshop that will have the D-Max-specific scanning gear to determine the cause or even narrow it down.

For the record, the SVS stands for Service Vehicle Soon, but I’m afraid even that’s a fairly generic recommendation and doesn’t get you any closer to the cause. That said, when engine oil or transmission fluid gets beyond a certain temperature, the computer will often detect this and call for a change of fluids as a means of driveline protection. This could be what’s happening every time you tow.

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 car could be trying to trying to tell you that there’s something wrong with the key. So start with the basics. The most common cause for the key to not operate the ignition and security system (which is why the engine won’t start) is because the key’s battery has gone flat. Change it and see if that works. At the very least, try the second key (that should have come with the car) to see if it will operate things properly.

If not, then you have to start digging deeper, at which point the cause could be a glitch within the car’s body computer which is the brain that controls everything from the power windows to the central locking and immobiliser. If that’s the case, then an auto electrician is probably your best bet, but definitely check the key’s battery first.

The digital displays on modern cars are known to sometimes randomly fail for no apparent reason. Sometimes it’s the whole display that fritzes, other times just a smaller part of the display will disappear. Usually, replacing the LED module is the fix.

From memory, this model D-Max groups the fuel and temperature gauges, odometer and the gear position information into a small unit in the middle of the dash binnacle. Which means it might be a bit complicated re-connecting the temperature and fuel tank sensor units to the new module, as well as making sure the new odometer reads the correct mileage for the vehicle. An auto electrician should be able to handle it, though.

Technically, of course, any car without a working gear-position indicator is unroadworthy, so this needs to be fixed rather than ignored.

A lot of people think that a car that is switched off and locked won’t be draining its battery at all. But that’s not the case. Electronic equipment often imposes a constant drain on the car’s battery, and things like the stereo (for keeping stored radio frequencies) and any alarm system can create a constant draw on the battery. And when you think about it, even the remote central locking needs to be 'alive' all the time so that it can identify and act on your command to open the doors and prepare the car to be started.

However, I wouldn’t expect a nearly new car battery to be unable to survive a single week of not being driven. So maybe there’s something else going on. It could even be that the battery itself is faulty and not holding a charge as it should.

I’d be talking to the dealership as a fault with, say, a luggage area light staying on or any other piece of equipment not switching off when it should, is potentially a warranty claim. Just don’t expect Isuzu to cover the cost of a new battery. Like tyres and brake pads, batteries are considered consumables and are generally not covered by a new-car warranty. Although if it’s an electrical fault on the car that has caused the death of the battery, I reckon it’s an arguable case.

A car that’s left to sit for a length of time will often develop a flat battery as things like the clock and security system slowly drain the battery. But this should not happen in just three days.

If there’s absolutely no drain on the battery (as checked by your electrician) then suspicion turns to the battery itself. It may have done this since it was brand-new, but the battery could have a manufacturing flaw or internal damage that means it won’t hold a charge beyond three days. Borrow a different battery and see if the problem goes away.

Not being able to match a vehicle’s official fuel consumption number is not just common, it’s something just about every owner discovers the hard way. That’s because the test that determines the number is a laboratory test, not a real world one. The test figure serves as a comparison between different makes and models, not a realistic expectation of fuel consumption.

However, the additions you’ve made to your car will all increase fuel consumption. A nudge bar and tow bar both add wight and a set of roof bars can easily add a litre of fuel to every 100km travelled thanks to increased aerodynamic drag. Even the GVM upgrade might make a difference, especially if it sits the vehicle up higher, affecting aerodynamics even further. If you’ve also fitted bigger tyres, fuel consumption will rise even more. To be honest, I reckon 10 litres per 100km is about right for this vehicle and matches most other vehicles of this type. Don’t forget, either, that an Isuzu MU-X is a much bigger, heavier vehicle than a Subaru Forester.

It’s difficult to be definitive here without actually driving the vehicle, but there are at least two possible sources for this. The first is the simplest and involves either a wheel and tyre or driveshaft that is out of balance. That should be easy to diagnose and fix.

The second possibility is that the vehicle’s driveline (engine, gearbox and transfer-case) has what’s called a resonant frequency that, when reached at a particular speed range, will result in some weird harmonics and vibrations which is possibly what you’re feeling and hearing. This becomes worse when the torque converter locks up (to save fuel) and there’s no slip in the driveline to absorb these bad vibes. By shifting back to fifth gear, you’re raising the engine revs and moving it out of that harmonic patch.

I’ve heard that Isuzu has been remapping some ECUs (on-board computers) to try to move this harmonic zone into a different (higher) speed range (by manipulating the torque-converter lock-up point) where it won’t be a problem to most owners. The fact is the Isuzu diesel has never been the most refined one out there and some vibrations and harmonics are relatively common, However, they shouldn’t be bad enough to ruin your enjoyment of the car.

In the old days, a different exhaust was often enough to move the harmonics around or get rid of them altogether, but I can understand why that’s not really an option on a brand-new vehicle.

This really does sound a bit like a head gasket problem. Even though the coolant and oil aren’t mixing (as you might expect with a blown head gasket) if the gasket blows between the coolant passages and the combustion chamber, the pressure of the engine’s combustion (particularly when the turbocharger is boosting when, say, climbing a long hill) can pressurise the cooling system, leading to the sorts of problems you’re having, including ejecting the coolant all over the place.

But until you’ve done a couple of simple checks, there’s no way of knowing whether there’s a blockage or other problem with the cooling system that is allowing the engine to become too hot. At that point, the coolant will also force its way out of the engine with a similar set of symptoms. A chemical check (called a TK test) will be able to identify whether combustion gasses are finding their way into the coolant, suggesting a head gasket failure., A good mechanic should also be able to tell if there’s a blockage in the coolant system or a problem with the coolant pump.