Here's a few ways to connect the Lock-up function on a TH 200 R4 Transmission.

This transmission is supposed to have low oil pressure
in fourth gear to improve gas mileage, so the lock-up has to
be in use to prevent premature faliure
of the transmission.

Lock-up wiring diagram 1

This is the way I have connected the lock-up on my El Camino.

This half-automatic system lets you activate lock-up by pressing a button, and it disengages as the brake pedal is depressed due to a double action stop light switch from a newer car. Mine is from the same car as the transmission.

Lock-up wiring diagram 2

Crude, but functional.

This system uses the 4:th gear indicator wire from the transmission. Lock-up is activated by the dash board switch, and as fourth gear is in use, the lock-up will be engaged as long as the switch is "on".

Lock-up wiring diagram 3

The best system, I guess, but you'll need a few parts and some fiddling with the adjustments on the vacuum sensor.

This is a fully automatically functioning lock-up system and, as I've understood, often used by transmission and rod shops to practically hook up a TH 200 4R to an older engine. When the 4:th gear indicator opens the circuit, and the throttle is eased for cruising (engine manifold vacuum rises) the lock-up is engaged.

The 4:th gear indicator in my trans is of the normally closed variant but can be substituted for a normally open one. In order to change it the oil pan needs to be removed. I don't know how much current the indicator can take, so I'd suggest using a relay anyway, in which case there isn't much use changing it...

It may be a good idea to use the same stop light switch as in Diagram 1.


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