SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/cdl-abs-malfunction-lamp

What color is the ABS malfunction lamp on trucks and trailers?

Yellow.

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  1. Red
  2. Yellow ✔
  3. Blue

Why: Vehicles with ABS have yellow lamps that warn you when it is not working. On trailers the lamp is on the left side, front or rear corner.

Huh, didn't know that: If your ABS fails, you still have regular brakes; get it serviced soon.

The dad joke
Why was the yellow lamp so cheerful? It always had a bright outlook.
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References

Answer: Yellow. Vehicles with ABS have yellow lamps that warn you when it is not working. On trailers the lamp is on the left side, front or rear corner.

  1. California Commercial Driver Handbook (DMV) www.dmv.ca.gov/portal/file/california-commercial-driver-handbook-pdf
    Vehicles with ABS have yellow malfunction lamps to tell you if something is not working.
    Checked 2026-10-10.

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