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How-To: Torque Converter Lockup Switch


Old 07-30-2008
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How-To: Torque Converter Lockup Switch

Written by: 04blackedge and TrePaul86

This is a how-to on wiring up a switch to lock you torque converter up so your truck will not move. This is a extra defense in having your truck stolen, you can also use this to lock in your highest gear when you cruising on the highway, increasing your fuel efficiency.

Most of those how-to was copied from a diesel how-to for this mod, I changed the parts that needed to be.

DO NOT flip the switch when your going at slow speeds, you will mess something up. Flipping the switch at low speeds can cause the truck to stall out and flood the engine

Tools Needed:

Wire tap
A 2-prong switch (Here's some Radio Shack part numbers 275-325 275-613 275-617 275-693)

This is optional if you want to wire up a LED to show if the switch is on or not, I used a already wired up LED so you don't need to do any soldering. You can find these at Radio Shack as well, here's 2 part numbers: 276-270 276-271

The PCM controls the solenoid on the torque converter. When it is time for the TC to lockup, the PCM communicates to the solenoid to lock up the torque converter.

Step One
Locate the oval-shaped connector on the passenger side of the transmission. It runs over the transmission to the driver’s side and up to the PCM. You are looking for the purple w/ yellow tracer (it might look like a blue with orange tracer. We have looked at SEVERAL trucks and they all look similar) wire coming out of pin 4 on the 12 pin connector. This is the wire that controls the lockup of the torque converter. Tap into this wire with a piece of 16-18 gauge wire and run into the cab through the firewall. Be sure to install a rubber grommet when routing wires through the firewall so the wire doesn’t rub through.

Step Two
Find a suitable switch to install in your cab. For the most part any switch can be used

The switch can be installed without the LED indicator and the LED can be installed without the switch. Run a ground wire to one side of the switch and connect the other side of the switch to the wire you ran into the cab from the transmission. When the switch is flipped it will ground the signal from the transmission and lock up the torque converter. Connect a 12Volt wire to the hot side of the LED and connect the ground side of the LED to the wire you ran inside the cab from the transmission.

Now your Overdrive light in the cluster might flash at you when you turn the switch on if your cruising on the highway, no worries though its just the computer doing its job it won't do anything except flash. Make sure to turn the switch off if you have to slow down or speed up though. There is a way to prevent it from flashing, but its pretty complex.


Last edited by 04blackedge; 07-30-2008 at 05:04 PM.
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