I have a '91 4Runner w/ 2WD & Automatic. I have had two transmissions in it and they both do the same thing. After driving for a while, (time varies) the "OD off" light starts flashing and continues until you turn off the ignition. After a while it starts again. Also, when I read the engine diagnostic codes, the OD light flashes with the engine light but not in sync with it. Could it be a problem with the radiator instead of the trans.?