2027 Isuzu D-Max Pricing and Specs

Making a change like remapping the transmission in a brand-new car could potentially bring you undone come warranty time. If it is deemed those changes in any way contributed to the downfall of the transmission, even years later, the manufacturer might refuse your claim.

The best advice it to approach Isuzu to see if any running changes have been made to the transmission programming, as these would be factory changes and would not jeopardise your warranty. A jerky transmission is often cured by a new software package and car-makers often offer these at the next service. But going for an aftermarket re-tune or recalibration of the transmission is potentially asking for warranty hassles down the track.

What you’re experiencing is the front and rear axles fighting each other. Us old-timers call it axle wind-up and, as the name suggests, it’s what happens when the various wheels need to turn at different speeds, but can’t.

When you’re in 4H, you’re effectively driving the front and rear axles at precisely the same speed. Logic says this shouldn’t matter, but, depending on what lumps and bumps they’re covering at the time, there are times when the front and rear wheels need to travel at slightly different speeds. Throw in full steering lock, and you’ve just made things very difficult for the driveline with all sorts of competing forces being fed around the various tyres, axles and driveshafts.

This is far from limited to the Isuzu, and many four-wheel-drives without a centre differential (such as your D-Max) when driven at full lock in 4H will exhibit the same shunting and apparent loss of power. The power loss, meanwhile, is simply those front and rear tyres fighting each other; nothing to do with the engine at all.

When you shift back to two-wheel-drive (2H) the front and rear axles are suddenly free to turn at different speeds, and the sensation goes away. This whole situation is why you can’t use 4H on dry bitumen in a four-wheel-drive vehicle without a centre differential. Meantime, there’s no fix for it other than learning when and when not to engage 4H.

Any time you have a grinding noise from the driveline of a car, it’s time to have it checked out. That’s because continuing to drive it in that condition might cause more damage than was already there. Grinding sounds from the area of the transmission can indicate worn bearings in the gearbox which, if caught early enough can sometimes be replaced without resorting to a complete transmission replacement. Even so, it will be a big job as the gearbox will need to be removed and pulled apart.

You may also find while you’re inside the transmission that there’s other wear that needs to be addressed, at which point the decision becomes whether to repair or replace. You can buy a reconditioned transmission from a specialist shop, or a second-hand one from what was once called a wrecking yard. If you do the latter, make sure the used gearbox has been tested and comes with some sort of warranty. The cost of a replacement could be anywhere from $1000 to $10,000 depending on what you buy and where you buy it from.