P0736 Toyota Hilux

P0736 Toyota Hilux – Reverse Gear Slip in Aisin Automatics Explained

If your Toyota Hilux has logged fault code P0736, the problem is not electrical and it is not a software glitch. This code indicates that the automatic transmission is slipping internally in reverse gear under load. On Aisin automatic transmissions used in the Hilux, Prado, Fortuner, and Land Cruiser platforms, P0736 is a clear warning that internal hydraulic integrity is no longer being maintained.

P0736 in Toyota Hilux – Why Reverse Is Slipping in Aisin Automatic Transmissions

P0736 is defined as an incorrect reverse gear ratio. The transmission control module determines this by comparing turbine speed and output speed against the known fixed ratio for reverse gear. When reverse is commanded but the measured ratio does not match what the transmission is designed to produce, the ECU records P0736. This means the transmission is physically slipping. It is not guessing, and it is not reacting to a sensor fault.

Reverse gear in Aisin transmissions experiences very high torque multiplication, particularly in heavy vehicles like the Hilux that are used for towing, off-road work, and load carrying. Because of this, reverse is often the first gear to show symptoms when internal wear or pressure loss is already present. Many vehicles will continue to drive forward normally, which leads owners to underestimate the seriousness of the fault.

P0736 what happens

Common symptoms in Toyota Hilux vehicles with P0736 include delayed engagement into reverse, especially once the transmission is hot. Drivers may notice a pause before the vehicle moves, harsh engagement, or rev flare before reverse takes up drive. In some cases, reverse may work when cold but fail entirely after towing or manoeuvring a trailer. Limp mode or warning lights may appear intermittently, particularly after heat-soak conditions.

The root cause is almost always internal hydraulic and mechanical wear. Aisin transmissions rely on precise pressure control through the valve body to apply reverse clutch elements correctly. Over time, valve body bores wear, internal leakage increases, and clutch seals lose their ability to hold pressure. Heat plays a major role in accelerating this wear, especially in vehicles that tow without adequate transmission cooling.

This is why P0736 commonly appears after towing, reversing uphill, or slow manoeuvring under load rather than during highway driving. Reverse places high stress on the clutch pack while fluid temperature is already elevated, making any pressure loss immediately visible to the ECU.

Transmission Service Mistakes in Toyota Hilux

One of the most common mistakes is attempting to resolve P0736 with a fluid change or by clearing the fault code. While fresh fluid may temporarily improve engagement, it does not repair worn friction material, leaking seals, or valve body wear. Solenoids are also rarely the cause of ratio faults in Aisin transmissions. When P0736 is present, the transmission has already failed a load-holding test internally.

Brisbane Tuning & Turbo approach

At Brisbane Tuning & Turbo, we treat P0736 in Toyota Hilux vehicles as a transmission integrity fault. Our diagnostic approach focuses on validating whether the transmission can still hold load safely. This includes scan data analysis, temperature-based testing, and real-world load validation. The goal is to determine whether the transmission is stable, degrading, or at immediate risk of failure, not to upsell unnecessary repairs.

Depending on the condition of the transmission, the correct solution varies. In some cases, our professionally rebuilt and validated valve body can restore pressure control if clutch damage has not progressed too far. In other cases, torque converter heat load and internal wear mean a more comprehensive repair is required. Where reverse clutch damage is already present, a full rebuild with upgraded components is the only reliable long-term fix.

Reverse gear failure in Aisin

Reverse gear failure in Aisin transmissions is rarely isolated. Once P0736 appears, similar wear is usually present in other clutch packs even if symptoms have not yet shown. Partial repairs without proper validation often lead to repeat failures and significantly higher repair costs later.

Continuing to drive with P0736 is risky. Forward gears may still function for a period of time, but every reverse engagement increases internal damage, particularly when the transmission is hot. Reversing trailers, parking on inclines, and slow off-road manoeuvring accelerate failure. Early diagnosis can often limit the scope of repair. Delayed action almost never does.

If your Toyota Hilux, Prado, Fortuner, or Land Cruiser has logged P0736, the next step should be a proper transmission diagnostic that validates internal integrity under load. Guesswork and quick fixes usually turn a manageable problem into a major rebuild.

If you’re seeing this fault code, book a paid transmission diagnostic before the damage escalates. It’s the only way to get certainty about what’s actually happening inside your transmission.