Ask The Guide

Many mechanics at this point would put their money on a bad earth somewhere on the car. Even though the LED light is working, the car’s computer thinks otherwise and, since LEDs draw so little current in the first place, they can be a bit hard to diagnose. Even so, the fast flashing suggests that there’s definitely a problem. To be honest, an auto electrician is probably your best bet at this stage.

Some owners of older cars have found that switching to LED headlight globes can cause the car to think that there’s a blown light somewhere as the current being drawn by the LEDs is so small compared with the normal globes the car came with. Fundamentally, the computer can’t see the current that should be being drawn when the lights are on, and fires the check-light warning symbol. You may find it’s the LED indicator light unit itself that is faulty. These can develop random failures in the internal circuitry that controls them.

The first thing to do, though, is to try the home computer reset which involves disconnecting the battery overnight and seeing if that calms the computer’s nerves. It might not work, but it’s free to try.

This is probably a simple case of an automatic transmission doing what it’s designed to do. In order to keep the engine in its comfort zone (and making sufficient power and torque to haul the caravan at the speed you’ve chosen) the transmission will shift through its gears to achieve that happy balance.

Any time you encounter a hill or even a headwind (and it’s more so with a heavier caravan) the transmission will assess what speed you want to hold, and then (via changing gears) keep the engine at a speed that supplies the necessary performance. Even a hot day can cause a change in the shift patterns as the transmission aims to take the strain off the cooling system by giving the engine and easier time. Again, a big, heavy caravan will amplify this effect.

However, if the transmission is changing gears for no apparent reason, then you may need to have the calibration checked and perhaps even reprogrammed. Don’t forget, though, that a modern transmission is a pretty clever piece of gear that can even choose to shift down gears going downhill to take the strain of the vehicle’s brakes. Don’t confuse an active transmission with a dud one. And if you still think the behaviour is odd, then an electronic scan of the vehicle might provide more information.

Any time you have a dull, thudding or clunking noise inside an engine, it’s best to not drive it any farther and have that noise checked out. You may be right and the problem is an injector, but if it’s a serious mechanical problem inside the crankcase, you may find it suddenly lets go with catastrophic results.

Even if it doesn’t fail completely, you may be doing extra damage to the crankshaft, con-rods and bearings (and more) by continuing to drive the car. The problem could also be with the gudgeon pin(s) which secure the pistons to the con-rods. This is also something a mechanic would investigate.

The fact that the noise comes and goes with engine speed could be related to changes in the oil pressure masking the noise as engine revs rise. Bottom line? Have the car checked by a mechanic who should be able to pinpoint the noise. But be prepared for major expense if the engine has serous internal wear or damage.

Most mechanics would go back to basics for this one. With the engine running, you place the leads of a volt-meter across the terminals of the battery. This will tell you how much power the alternator is putting into the battery to keep the latter charged. You want to see a figure of up to about 14.5 volts, and anything less than about 13 volts suggests the alternator is struggling.

If you get a low reading, try the test with the engine just off idle as this can sometimes wake the alternator up and get it pulling its weight. Don’t forget to do the test with all the lights ad stereo off, and the air-conditioning switched off, too.

Modern cars absolutely hate having low battery voltage. It throws everything into chaos and can easily produce the sort of problems you’re having as the major components of a car are, these days, all controlled by computers.

By turning the car off and on again, you’re effectively performing the old Alt-Ctrl-Del function to reboot a home computer or laptop. As such, and especially since the transmission works perfectly when you reset it, this is almost certainly an electrical problem. A more permanent reset might be needed, so try leaving the battery disconnected overnight and then reconnect it next morning. This will often return things to normal.

The manual gearshift in a car can be quite a complex assembly with linkages, cables and pivots all crucial in maintaining the correct feel and shift precision. Any wear that develops in these parts or the bushes and bearings in which they run can contribute to a sloppy or loose gear-change.

But this is usually a problem seen in older cars, not a nearly new one. But my other question is where you bought a 2023 JMC Vigus, as the brand left Australia in 2018, tanking after poor sales over just a handful of years on the market.

The symptoms here point to a stuck flasher relay. This is the electrical component that not only powers the indicator lights, but makes them flash (and produces the steady clicking sound you hear when the indicators are on). The contacts in these units can become stuck at which point the lights can become stuck on.

Why does it still happen when the ignition is off? Because the flasher relay is powered up even when the ignition is not. That’s so you can have the emergency hazard-warning lights flashing even though the vehicle is locked and the keys in your pocket. A new flasher relay unit should fix it.

Okay, here’s the bottom line: All engines use a little bit of oil. If they don’t there’s either something wrong with the oil pump, or the owner is kidding themselves and not checking the oil level correctly. Modern turbo-diesels also 'breathe' a little oil back through the engine as part of the emissions control system, and owners with an aftermarket catch-can system often find a bit of oil winds up in there instead of being burnt in the engine.

The question is how much is too much. I don’t think 700ml per 2000km is excessive and your dealer’s views will be based on the official figure from Isuzu. But in the real world, owners are reporting oil consumption of around a litre to 1.5 litres per 5000km. At which point, your engine is right on the money.

How you drive the vehicle and whether you tow a heavy load will also affect oil consumption, as will ambient temperature and the type of oil you use. It’s a fact that modern, lower-friction engines are designed to use a little oil in the name of saving fuel, and it’s something car owners need to get their head around. Keep an eye on that dipstick and you should be fine. Checking the oil on a regular basis will also tell you whether the engine’s drinking habits have changed; a much more valuable piece of knowledge to have.

On older cars like this one, some pretty strange electrical things can start to happen as switches and wiring ages. The first thing to check for is that there’s not a cargo area or interior light staying on when it shouldn’t and subsequently flattening the battery.

But the failure of the stereo and temperature gauge both point to a body computer problem (as does the battery going flat). The body computer basically controls all the car’s functions that are not driveline related. So, the central locking, lighting, entertainment, security, power windows, climate control and much, much more are body-computer driven. And if this computer fails, lights can turn themselves on, the central locking can cycle over and over again and various other electrical bits and pieces can switch themselves on and drain the battery.

But there’s one other check to make before blaming the computer (which, on a 1994 Corolla, won’t be as complex as one on a more modern car), which is to make sure there are no bad earths on the car. Failing gauges are a common symptom of a bad earth somewhere on the car, and if that’s the case, you might find this is also causing the starting problems by not allowing the battery to fully charge when the car is driven.

This sounds like a fairly simple case of the engine setting up a harmonic vibration through the car. It’s not an uncommon thing and diesels are worse than petrol engines purely because they vibrate more, particularly at idle. By revving the engine slightly, you’re changing the frequency of the engine’s vibrations and moving them out of synch with what’s called the 'natural frequency’ of the rest of the car.

Why does it manifest at the steering column? Because the column is a long, flexible (in a micro sense) shaft that is far more prone to picking up vibrations than a short, more solid part of the car. Why is it happening now all of a sudden? Probably because there’s some wear in the car somewhere. Your call to change the engine mounts was a good one as these can wear and cause this very problem. But, equally, the wear could be in the exhaust system or one of the points where it attaches to the car, a heat shield, the torque converter, or maybe even a piece of the car’s sheet metal that has come loose and is moving slightly.

The quickest fix is to bump the idle one or two hundred rpm and see if that moves the engine out of the vibration zone at idle.