Solid State Relay for Lock Up Torque Converter
When you apply pressure to the brake peddle you energize the relay and remove 12 volts from the ECM.
Run #85 to the brake light side of the stop light switch (cold side). #86 to ground. 85 & 86 is the coil. #30 is the common and 87A in the normally closed contact. The Red wire for the ECM goes to 87A normally closed contact. #30 common goes to ignition 12 volt. #87 normally open contact is not used.

Relay
NTE R51-5040-12
SPDT 40A-12vdc.