Transmission Light On

About the Automatic Transmission Light

Transmission warning lights

Transmission warning lights

In order for modern cars to have smooth gear changes at the right times, the Automatic Transmissions are fully electronically and computer controlled. The device that controls them is called the Automatic Transmission Electronic Control Unit (Automatic Transmission ECU) sometimes called an Automatic Transmission Computer.

If the Automatic Transmission (AT) light is on in your vehicle, it indicates that there is a problem with the transmission system. The AT light is typically located on the dashboard and is often represented as a gear with an exclamation point.

Why is the Automatic Transmission Light On?

Below are some common reasons why the AT light may come on:

  • Low Transmission Fluid: One of the most common reasons for the AT light to come on is due to low transmission fluid levels. If the fluid is low, it could cause the transmission to overheat, resulting in damage to the transmission components.
  • Malfunctioning Transmission Control Module: The Transmission Control Module (TCM) is an electronic component that controls the operation of the transmission. If the TCM is malfunctioning, it could cause the AT light to come on.
  • Sensor Malfunction: Many vehicles have sensors that monitor the operation of the transmission system. If one of these sensors is malfunctioning, it could cause the AT light to come on.
  • Damage to transmission parts: The AT light could also come on if there are mechanical problems with the transmission, such as a worn-out clutch or damaged gears.


What happens if you drive with the automatic transmission light on?

  1. Problems with gear shifting and performance: If the AT light is on, it indicates that there is a problem with the transmission system, which can cause reduced performance, such as difficulty shifting gears, a rough ride, or a decrease in acceleration. You may also experience unexpected stalling as the engine struggles to keep up.
  2. Damage to transmission components: Continuing to drive with the AT light on can cause damage to the transmission components, such as the gears, clutch, or solenoids. This can result in more costly repairs down the line.
  3. Increased risk of accidents: A malfunctioning transmission can cause unexpected changes in vehicle speed or cause the vehicle to stall, which can increase the risk of accidents, especially if you are driving in traffic or on the highway.

Automatic Transmission Diagnostics & Servicing in Hamilton

At Grimmer Motors our highly experienced, skilled, and trusted mechanics have all the latest scan tool technology to read and then diagnose the diagnostic fault code and live data information in your automatic transmission

Please Note: Electronic Tests depend on the vehicle technology and may not be possible on some vehicles.

Contact us now to book your car in for a scan, to have us quickly and cost-effectively diagnose and repair your automatic transmission.

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Live/work in any of the following areas? Grimmer Motors could be extra convenient for you.

  • Fairfield
  • Fairview Downs
  • Enderly
  • Claudelands
  • Peachgrove
  • Hamilton East
  • Chartwell
  • Chedworth
  • Central Hamilton
  • Forest Lake, Beerescourt
  • Frankton
  • Melville
  • Waikato




Grimmer Motors Ltd


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