1997 T4R, 2.7l auto, 170k
Truck stalled out on the highway in bad alternator fashion. Radio cut out, headlights dimming then she acted like she was running out of gas.. Had the alternator rebuilt and got a new battery. I still get no reading from that alternator AT ALL.. Took her back and the fella said he checked the alternator and it is working perfectly.. He said it's a wiring issue and it is "the yellow wire that's not getting power" (The plug on the VR)

I take the truck home, start it up, poke into the 3 wires on the back of the Alternator.. Reading as follows: white- 11.96(same as batt) red-.08 YELLOW- 11.18.. Looks like it gets power to me! I don't know what the actual reading should be but they seem to all be hot with power.. PLEASE HELP!!


If the voltage regulator is bad, Could that stop ALL POWER to alternator??

Alternator is garbage. With the engine running, you should be pumping 13-14 volts. The wires you were measuring are just receiving reference voltage from the battery to tell the regulator to operate the alternator.

My suggestion, get your money back from that guy, because replacing coils and "looking" at the stator doesn't constitute a successful rebuild of an alternator. Re-manufactured or aftermarket new are really the only ways to go when dealing with a toyota.