Why does the overdrive on my Toyota Highlander 2003 (187K miles( shut off when driving highway speeds?
Welcome to the forum…
Do you have a check engine light (CEL) on?? If so what is the code, if not you can check for history or pending codes…
You may have to go to live data on a scanner to see if the shift solenoid is being commanded to shift into OD (overdrive) or not, if it is but not shifting then you have a wiring issue or bad or sticking OD solenoid or even the TCM needing rehashed or replaced…
Also check your ECT (engine coolant temp) as to low a temp can cause the OD not to engage…
IIRM a CEL will cancel the OD on your vehicle…
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Have you accidentally hit that little overdrive button on the shifter? I do that sometimes in my Highlander (2007), and people who borrow it often do that.
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