Hello good day... i have a 2000 forester with original transmission. The problem i got is that my power light flashes non stop and the transmission in is field safe mode where it shift from 1st to 3rd. i had all the solenoids checked out and my TCU refuses to connect to the OBD11 ... my transmission also makes a rattling noise which increses with RPM. any help would be greatfull 

The power light is telling you that you have a problem with (duh) your transmission. 

The rattling noise could very likely be a broken or cracked flex plate, but that alone wouldn't put it in safe mode and a bad torque converter (very common) wouldn't give you warning lights because it's purely mechanical.

 

We used to rebuild transmissions as well as engines, so I've seen the job and I don't want it.  I think you need to find either a reputable transmission shop that will do a Subaru transmission (not all will...they're rather complex) or a decent low mileage replacement. (Don't forget to match the gear ratios!)

OBd2 doesn't interface with the TCU.

There is a way to get TCU codes manually. I don't know the exact method for that year, but you can search google for the way. There's a black 6 pin plug under the dash on the left hand side with two ground pins taped further up in the harness. One of the ground pins is pushed into one of the terminals in the black plug and you turn the key On then do a secret handshake kind of thing and the light will flash any stored codes.

ok... i think its a electrical problem.. i started my car today and it worked fine.. no problems and the power light remained on ...no noise and gears changed correctly and smoothe... . as i switched off and start back .. once again the light flashes :/  and back to field safe mode.. possible reasons/??? TCU needs to change?? harness break contact ?? no current to TCU?? poor Grounding? ??? 

question is there a diode circuit in the transmission harness? 

Hmmmm, check the big connector(s) that go to the trans.

Dunno about any diodes inr the trans wiring.

my assumption is... its a issue with the innner harness . the harness of the transmission are all good. I did a continuity test from the pins to the soleniods.