First off, this issue is caused because the car for all intents and purposes is a 2JZGTE swapped 95 sc300 without any of the factory traction control components.

Relevent mod list:
1JZ Engine
JDM 2JZGTE harness merged with USDM sc300 harness
JDM Supra Auto ECU OBD1
Aristo Transmission

Symptoms:
The car runs and drives perfectly fine. The issue is the O/D flashes while the car is started/running/driving.

From what i can tell the engine ECU is looking for a signal from the TRAC ECU. Im just not smart enough with electronics to figure out what kind, or if its possible to fool the ecu. Ive done a lot of searching and even a researching of my own, but havent found anything that works

here are some diagrams and info i found from the TSRM

TRANS DTC89:



ECU terminal values


TRAC DTC 53

 

bump, ive tried a few things but no luck. I'm beginning to think I might have to have the trac ecu to get rid of it

 

Pm O.L.T he knows about this stuff.