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Toyota Tundra: Why is My ABS Light On?

If that annoying ABS light is ruining your day, learn what could be causing it with the help of this article.

By Jerry Perez - January 21, 2016

This article applies to the Toyota Tundra (2000-present).

Warning lights were created for a reason—to warn us of possible issues with our vehicle. Although, most times that pesky light on the gauge cluster can be created by benign issues, and nothing critical, such the case can be with the ABS warning light. There are many reasons why such light may be turned on, so use this guide to uncover what your particular issue may be. It's simple.

Toyota Tundra Why is ABS Light On

Materials Needed

  • 10mm open wrench
  • Floor jack and jack stand
  • Brake fluid
  • Lug nut wrench

Step 1 – Check your brake fluid

It could be dirty.

The brake fluid in your Toyota is designed to flow freely to operate moving parts in your braking system. If the fluid is dirty or contaminated, it will not have the same effect. Follow these steps:

  • Use your lug nut wrench to remove the front tires. Jack up your vehicle and support on jack stands.
  • Open the hood and remove the brake fluid reservoir cap, and inspect brake fluid condition.
  • If fluid is looking dark and not clear, use the 10mm wrench to open the bleeder screws on the calipers.
  • Give the system time to flush the entire system of old fluid.
  • Top off with new fluid and close bleeder screws.
  • Toyota Tundra brake diagram
    Figure 1. Brake component diagram.
  • Toyota Tundra brake caliper bleed valve
    Figure 2. Brake caliper bleed valve.
  • Toyota Tundra brake reservoir
    Figure 3. Bleed fresh fluid through the system.

If the result of the fluid change didn't fix the problem, move to the next step.

Step 2 – Check your sensors

They could be old or damaged.

Your Toyota is filled with sensors everywhere, but specially in the ABS and braking system in general. Sometimes these sensors fail or become damaged from human error. It's common for routine maintenance to damage the wiring and ruin the sensors.

  • Jack up the vehicle and secure it.
  • Remove the tires.
  • Inspect the wiring as well as brake lines that connect to the calipers and the brake master cylinder.
  • If any lines show abrasion or damage, they may need to be replaced.
  • This job is best performed by an expert at a dealership or repair shop.
ABS sensor wire
Figure 4. Wiring for ABS sensor mounted against wheel hub.

If that doesn't fix the problem, move to the next step.

Step 3 – Reset the electrical system

There could be an electrical glitch.

Sometimes lights and sensors get stuck and need resetting. Follow these steps:

  • Open the hood and locate the battery.
  • Use the 10mm wrench to disconnect the negative (black) terminal first, and then the positive (red).
  • Wait five minutes and reconnect.
  • Warning lights should be off. If not, visit the dealership or repair shop.
Disconnecting battery
Figure 5. Disconnect battery.

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