Toyota Tundra 4lo light is flashing. Reasons and fixes

The Toyota Tundra – a beloved full-size pickup truck, known for its unwavering reliability and versatility, still faces its own set of challenges like all vehicles.

One such issue is the flashing 4LO light – a source of confusion for owners who may not be familiar with its meaning. In this piece, we delve deeper into the reasons behind this warning light’s sudden appearance and outline the steps you can take to resolve it.

Root Causes of the Flashing 4LO Light

  • A failed transfer case shift motor could trigger the 4LO light to start flashing, potentially due to a damaged wiring harness or a blown fuse.
  • The transfer case shift control module controls the transfer case shift motor, and its failure could result in the same flashing 4LO light. Wiring harness damage or a blown fuse could also be the culprit.
  • Improper positioning of the transfer case shift lever can cause the 4LO light to flash. A faulty lever, damaged linkage, or a worn transfer case could be the root of the problem.
  • The transfer case, responsible for sending power to both the front and rear wheels, can trigger the flashing 4LO light if it’s damaged or worn. This could be due to a faulty transfer case, a damaged drive shaft, or a worn transfer case output shaft.

Cost of Solutions

  • Replacing a failed transfer case shift motor could cost anywhere between $250 to $500, depending on the make and model of your Toyota Tundra.
  • A new transfer case shift control module could range from $400 to $800.
  • Adjusting or replacing a faulty transfer case shift lever could cost anywhere between $100 to $200.
  • Inspecting and possibly rebuilding or replacing a damaged transfer case could range from $800 to $3000. A brand-new transfer case would cost even more.


In conclusion, the flashing 4LO light could stem from various reasons, including a failed transfer case shift motor, control module, lever, or transfer case.

The cost of fixing this issue could vary greatly, from $250 to $3000, depending on the underlying cause. Therefore, it’s crucial to have your Toyota Tundra inspected by a professional to determine the root cause and find the best solution.

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