T/C unlock switch ?

[MD500E]

I wired in a 3 way "mystery switch" into my 98 years ago that would allow me to have forced locked, stock, and forced un-lock mode. Over time I found I liked to drive around on back roads with the converter unlocked and then flip it back to stock mode when I hit the highway. Is there any way I can wire a simple switch into my 05 to keep the torque converter unlocked? Any info would be appreciated.

Kevin

 

[cerberusiam]

You can but it needs to be wired differently. The newer trucks monitor the circuit for opens and shorts. whne they see something like that it goes into limp mode. In oreder to do a lockout on either the TC or OD it needs to supply the ECU with a resisted voltage that makes it think things are fine as long as resistance stays between 5 ohms and 100 ohms.



Following diagram is one way to do it.



#ad

 

[MD500E]

cerberusiam, thanks for the reply. I am still trying to make sense of how it is wired. Does the computer ground a wire to lock the converter and then have a separate sense wire to check on the circuit. Has anyone had success wiring in a switch on these newer trucks? I will have to get my hands on the shop manual to study the wiring. I would love to have two switches, one to unlock the torque converter and the second to lock out overdrive.

 

[cerberusiam]

cerberusiam, thanks for the reply. I am still trying to make sense of how it is wired. Does the computer ground a wire to lock the converter and then have a separate sense wire to check on the circuit. Has anyone had success wiring in a switch on these newer trucks? I will have to get my hands on the shop manual to study the wiring. I would love to have two switches, one to unlock the torque converter and the second to lock out overdrive.

The sense wire in the diagram is the same wire that is monitored for resistance. The ECU just grounds the sense wire internally to activate the solenoid. It works the same way on the TCC circuit.



The OD circuit is a little bit more involved because of the the VB is setup. You cannot knock the trans out of OD with the TC locked, and when you manually lock the TC in 2nd or drive it will lock and stack shift into OD immediately. Its the way the VB is designed. In order to lock out OD you need to be in drive to keep it out.



FYI, I am using BD Powers OD lockout box to handle that and it works great. Allows me to lock out OD and still keep the aggressive shift\lock routines that TH gives.



The above diagram was deisgned to lockout OD but you could use it to do the same with the TC clutch. If you can find the right resistor in the correct load you don't need a solenoid as shown above. I did it like that to show someone else how it needed to be wired. You would have to figure out how much resistance and load the original solenoid is to match it.