fault in the BSM?

2023 TOYOTA HIGHLANDER
16,578 MILES • 3.5L • V6 • 4WD • AUTOMATIC
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ANDRIN ATEM
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Vin: 5TDDZRBH8MS063087

fault codes for blind spot monitory. C1AB4 C1AB5

My I have the wiring diagram of this BSM
Dec 30, 2025 at 7:27 AM
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STEVE W.
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Both of those codes are open circuit codes. The AB4 is the left mirror the AB5 is the right mirror. Do you know if this truck has the memory seat option? The VIN you listed comes back as a 2021 that has two open recalls and it uses different wiring than the 2023 you have listed as they changed some things after 2021, what is the actual year of the truck you are working on? That will allow use to provide the correct information. The newer vehicles can be very easily damaged if you were to test the wrong wiring in the wrong way.
Dec 30, 2025 at 11:32 AM
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ANDRIN ATEM
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2020 I saw on the seat belt. I have attached an image of it.
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Dec 31, 2025 at 3:07 PM
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STEVE W.
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That means the belt was made in 2020, so the truck could be either year but possibly the 2021 if that is the VIN from the tag on the dash. Also need to know if it has the memory seats. FYI it also should have a door sticker with the build date on it.
Jan 1, 2026 at 1:02 PM