4th gear pressure switch question

[novaderrik]

since i will have the pan off for a fluid/filter change, i figured i would try to figure out why the torque converter doesn't lock on it's own. there is power to the plug on the outside- and if i jump the terminal on the ALDL connector, the converter does lock up- so the solenoid is good.
just curious if the pressure switch is a normall open or normally closed design so i can check it while the pan is off..
also, what is the "correct" valve body for an 84 t-type? it has a "BD" tranny made in the 84 model year according to the tag on the tailshaft, and i think the torque converter has "D5" stamped all around it.

 

[Lee Thompson]

code

I believe all 84-85 TR had a BQ code trans. 86-87--BRF
I would suspect the solenoid is not getting a signal from the ECM to lock. Don/t believe the 4th pressure switch would come into play.

 

[novaderrik]

if the pressure switch doesn't tell the computer that it is in 4th gear, then what, exactly, is it's purpose? would the ecm not want to know that it is in high gear and that it can now safely lock up the converter?
so, is it normally open or normally closed?

 

[novaderrik]

turns out the tranny is BQ code tranny- i was having a hard time reading the tag before.
anyhoo, can anyone help me out with my pressure switch problem?

 

[84ZZ4]

Every 200-4R I've taken apart has had a normally closed pressure switch which opens in high gear.