Need help with 09 Subaru Legacy

The AWD, ABS, AT OIL TEMP, and TRACTION CONTROL lights our on the AT OIL TEMP light and AWD lights flash. All these lights are on at the same time. Was told that the TCU was bad and I replaced it and nothing changed any suggestions? I have checked all the fuses as well to see if maybe something was there and everything was fine.


Connect a scan tool and retrieve ALL the fault codes

It is possible that one or more control units are not communicating

Check the AC ripple voltage while the engine is running around 1,500 RPM. It should be less than .1 volt. Excessive ripple can cause trouble with the warning lights and you may need to replace the alternator. Another simple thing you can do is just remove the plug in the back side of the alternator and then start the car and see if those light go away. If they do then you need to replace the alternator. The battery warning light will be on though of course.

Check the alternator. Our 05 Legacy GT(similiar generation) lit up like a christmas tree when the voltage regulator failed in alternator. It was spiking voltage.