4x4 only works when OBD2 is plugged in

Hi, 4hi/4lo lights flashing as soon as ignition is turned on, with switch still in 2wd. Plug in OBD2 before ignition and no flashing lights. 4x4 works perfect.

 

You have a bad ground between Ground Point EE on the back of the passenger side cylinder head and J/B No 2 behind the glovebox, we've addressed this before although no one has yet found where the wire breaks but we do have a fix.

See the thread below specifically Posts 236, 237, 254, 257, 259, 272, 274, 275, & 278 for more info.

https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/