Just documenting the TC lockup switch with pictures. I've had a PM requesting info on it and the poor mans propane setup.
Middle harness. Orange wire w/black tracer (might be a navy blue).
The following information is supplied at no cost or obligation.
Note that use of this method of lockup may be hard on vehicle drivetrain and may void vehicle drivetrain warranty. Use makes vehicle drive like a manual transmission in 4th gear such that vehicle may/will stall at low speeds/stops if lockup is not disconnected.
Note: Some 1996 automatics require computer to be reflashed by dealer for the lockup switch to work.
Step-by-step Instructions:
1. Install jumper wire in place of the trans relay in the Power Distribution Center (black box behind driver side battery) as shown in diagram below. This jumper wire will supply 12 volt positive to the transmission torque converter clutch solenoid. This jumper will be electrically hot thus it should be installed so as not to short against ground. I used two scraps of metal brackets to make prongs. You can get taps that will insert into the slots from any parts store. It was only what I happened to have at the moment.
Note: The position of this relay changes from one year to the next. Consult relay location chart on inside of relay box cover.
2. Install ground wire from the B11 orange wire with black stripe to a switch or relay such that the ground source can be turned on and off. The B11 wire is located in the middle computer connector located on the firewall behind the air cleaner.
3. Install the switch wherever you like. I installed mine to the left of the column. It's the black switch. The smaller switch is for my XTZ+.
4. Ground the wire. I used this screw under the dash.
5. Enjoy!
Note:You can use a double pole double throw relay from radio shack to automatically disengage the TC when the brakes are applied. I've got the relay, but haven't installed it yet on my truck. Here's a crude diagram of how it would be wired up.
The relay I bought from radio shack is
RadioShack.com - Cables, Parts & Connectors: Component parts: Relays & transformers: 12VDC/3A DPDT Plug-In Relay & Socket
I don't use mine except when I'm up to speed on the highways. I use it to counteract the annoying locking and unlocking that happens from the computer getting line noise. Hope this helps.
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1999 2500 4x4 Club Cab Sport.
ADRENALINE/
pulse 
, BHAF, FBD 150 sticks, Tunnel Ram Intake plate, Byrd's intake Horn, HE351 retrofit, Hamilton 110lb valve springs, A1 head studs, 5" FBD exhaust, Isspro Boost & Drive pressure gauges, fuel pressure gauge, Mallory Comp 250 pump, 1/2" big line kit, Draw straw, TC lockup switch, Stealth VP plate, BD TC, BD VB, Billet input, Derale pan.
462hp and 920ft-lbs 11/14/09, I know I can get 500hp...