Re: lockup transmission swap

Posted by Bob on September 03, 2002 at 08:38:22 from (66.231.125.137):

In Reply to: lockup transmission swap posted by Scott on September 01, 2002 at 22:31:24:

The wiring connector on the tranny may be hooked up internally in one of several ways.

Basically, you have the LOCKUP SOLENOID, and one or more PRESSURE SWITCHES.

Depending on how you tranny was wired for it's original application, the solenoid wire may go directly to the connector, or it may pass through a THIRD GEAR SWITCH (one of the pressure switches). This switch prevents to solenoid from applying in gears other than third. I believe some were wired to allow lockup in either second or third.

As for the lockup function being vacuum operated, the vacuum unit on the tranny is a vacuum modulator, which affects shift firmness, and timing. For LOCKUP, you need to get 12V power to the LOCKUP SOLENOID. Next paragraph tells how vacuum affects lockup, using the VACUUM SWITCH.

In OEM applications this was done by passing power from the IGN circuit through a brake pedal switch, and then through a vacuum switch that would only allow lockup above a certain manifold vacuum. The brake pedal switch shut off the lockup function as soon as the brake was depressed. The vacuum switch was connected to intake manifold vacuum, which is an indicator of engine load. Higher manifold vacuum indicates lower engine load, and lockup is permitted. In some OEM applications, the computer switches the 12V lockup power, and a separate vacuum switch wasn't needed, as the computer already knew engine load, and decided when lockup should occur.

For safety, you need the switch on the brake pedal, but from there you could run the wire through a toggle switch, and then to the tranny connector, and internally to the LOCKUP SOLENOID, possibly using the 3RD gear switch, if you can identify that. Then you can manually control lockup with the toggle switch. Email me, if you wish with any further questions.

Contrary to many naysayer's opinions, I have found that, with a properly operating transmission, the lockup function increases tranny life (it runs cooler), and increases gas mileage. This was another case where people are afraid of something new they don't understand, so many had the lockup function disabled.

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