Lock up switch

[wrichards]

Can somebody tell me the pros and cons of the torque converter lock up switches? I know someone that has it and loves it for breaking power and says it is saving his powertrain because of less shifting, locking and unlocking.

 

[Joe G.]

First of all you can destroy your torque convertor clutch if the lock up switch is misused! If you do not do that then it works very well. The thing to avoid is putting too much power thru a locked TCC. In other words no hard excelleration and no hard pulling. No lugging. Don't let it shift when it's locked and don't kill the engine by stopping with it locked. With all that said, I would not be without mine. My exhaust brake would be worthless without someway to force lock the TCC. I've rigged a push button on the floor near where an old style dimmer switch would be. That button is wired in series with the switch and the ground. By stepping on the button I can immediately and easily unlock the TCC. There are two basic ways to wire the switch. One way is to just put a ground on the TCC lockup solenoid wire by using a single throw single pole switch. There is a problem with this method. You cannot force an UNLOCK. I used a double throw single pole switch with center off. With this method the lockup solenoid wire is cut. The transmission end is attached to the center pole on the switch, the computer end of the wire to one of the outer poles, and the ground to the other. If the switch is in the center the TCC cannot lock even by computer control. Connected to one pole the lockup behavior is stock computer controlled. To the other pole the lockup solenoid is grounded so it will lock and stay locked.

 

[Jim Fulmer]

I wired a lockup switch on mine when I first got it and it works great, the converter slips real good now but there is a kicker, Mine had always stayed locked up on O/D when you mat it and I figure that is were most of the problems have come from. DTT mods are getting real close and when they are done the lockup switch will become and unlock switch as lockup is not needed for power.



Jim

 

[wrichards]

Thanks for th info, now I know how it works, my question is where do I find the solenoid to play with, and what are the advantages when driving with a lock up.

 

[Joe G.]

The only real advantage is that an exhaust brake will work. Otherwise it will NOT work with the auto trans. I normally drive with the TCC manually locked when I'm on the highway so that if I lift the exhaust brake will slow the truck quickly. The convenience of my floor button makes this work well for things like off ramps. Otherwise I leave it in the stock position. If I am towing in steep country I will force an unlock for uphill and force a lock for downhill.



I don't know where the wire is for the '98. It should be on the TST web site at http://www.tstproducts.com/ . The wiring is different for the 47RE trans that you have because the computer gets a knot in its shorts if it's wired wrong. The switch wireing is the same but the solenoid is accessed thru a relay so you have to mess with that.