T.C. lock switch w/pics
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Joined: Jul 2008
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From: Thomasville, GA
T.C. lock switch w/pics
Safety Switch in the dash:
Red wire from switch to transmission wiring:
Splice into PURPLE wire w/ YELLOW stripe:
The other wire from the switch goes to Ground. THere are two purple wires on the transmission bundle. One is purple w/ red stripe, other is purple w/ yellow stripe. You want the purple and yellow.
This is a manual switch so you must turn it off to unlock the converter. I recommend unlocking it under 20mph and ALWAYS when you come to a stop or you will kill the motor or just roll through the brakes.
When used it will keep trans temps down quite a bit. Also helps you engine brake better.
Red wire from switch to transmission wiring:
Splice into PURPLE wire w/ YELLOW stripe:
The other wire from the switch goes to Ground. THere are two purple wires on the transmission bundle. One is purple w/ red stripe, other is purple w/ yellow stripe. You want the purple and yellow.
This is a manual switch so you must turn it off to unlock the converter. I recommend unlocking it under 20mph and ALWAYS when you come to a stop or you will kill the motor or just roll through the brakes.
When used it will keep trans temps down quite a bit. Also helps you engine brake better.
Post Fiend
Joined: Oct 2003
Posts: 5,903
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From: MICHIGAN
I read somewhere that you shouldn't allow the engine RPM to go below 1300 with the TC locked. Something about the trans pump not producing enough pressure to hold the clutches from slipping. That's more of question than a statement...I want to do this mod too.
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Joined: Jul 2008
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From: Thomasville, GA
So that's basically what I go by.
Post Fiend
Joined: Oct 2003
Posts: 5,903
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From: MICHIGAN
Yep, you are right. Just found it. Scroll to the bottom of the page for the Disclaimer paragraph. This shows the mod for a 1999+....same thing only different 
http://forgotton.net/mods/tclock/index.htm
http://forgotton.net/mods/tclock/index.htm
Hotshot
Joined: Feb 2009
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From: Plankinton, SD
I'm not real familiar with this but was wondering when do you use it? When towing? Just curious cause I tow a lot and am making a list and gathering parts for a multi-project on my truck this winter and wonder if this is something I should do. Thanks
Fleet Mechanic
Joined: Aug 2007
Posts: 1,508
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From: The boonies by Dallas OR
Don't ever use these connectors on a vehicle, particularly underneath:
They WILL fail on you. I can't count the number of repairs I've done because of those connectors.
What's worse, they let water into the wire and it wicks along the strands and corrodes the whole wire.
Since the early 90's, vehicle manufacturers have gone to sealed connectors and the reliability of electrical systems have improved immensely. At a minimum, seal up the splices with liquid electrical tape. Better yet, get the sealing heat shrink found at many auto parts stores and seal them up tight like Ford does from the factory. You'll be happier in the long run.
They WILL fail on you. I can't count the number of repairs I've done because of those connectors.
What's worse, they let water into the wire and it wicks along the strands and corrodes the whole wire.
Since the early 90's, vehicle manufacturers have gone to sealed connectors and the reliability of electrical systems have improved immensely. At a minimum, seal up the splices with liquid electrical tape. Better yet, get the sealing heat shrink found at many auto parts stores and seal them up tight like Ford does from the factory. You'll be happier in the long run.
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Senior User
Joined: May 2004
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From: Vancouver
You should see the connectors on our engine harnesses at Western Star. They are built in Mexico and they must not have heat shrink down there. The terminals look look like the ones you would buy at an auto parts store if you were building it in your garage not on a new oem shop.
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Hotshot
Joined: Jul 2008
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From: Thomasville, GA
Don't ever use these connectors on a vehicle, particularly underneath:
They WILL fail on you. I can't count the number of repairs I've done because of those connectors.
What's worse, they let water into the wire and it wicks along the strands and corrodes the whole wire.
Since the early 90's, vehicle manufacturers have gone to sealed connectors and the reliability of electrical systems have improved immensely. At a minimum, seal up the splices with liquid electrical tape. Better yet, get the sealing heat shrink found at many auto parts stores and seal them up tight like Ford does from the factory. You'll be happier in the long run.
They WILL fail on you. I can't count the number of repairs I've done because of those connectors.
What's worse, they let water into the wire and it wicks along the strands and corrodes the whole wire.
Since the early 90's, vehicle manufacturers have gone to sealed connectors and the reliability of electrical systems have improved immensely. At a minimum, seal up the splices with liquid electrical tape. Better yet, get the sealing heat shrink found at many auto parts stores and seal them up tight like Ford does from the factory. You'll be happier in the long run.
Just had a lot of questions on how to do the mod so I crawled under the truck and took pics.
It is great for towing, especially when going uphill at speeds lower than the TC usually locks (below 45 or so) and will keep your transmission temps cooler. Also lets you use the engine to brake on downhill so you don't use your service brakes as much.
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Joined: Sep 2003
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From: North East Ohio
Squirt some silicone inside those connectors before you crimp them. Works great.
Personally I like the 'T' taps, same kind of design, but the intruding wire gets connected via a blade terminal and is removable without disrupting the crimp/connection in the original wire.
Personally I like the 'T' taps, same kind of design, but the intruding wire gets connected via a blade terminal and is removable without disrupting the crimp/connection in the original wire.
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
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'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
'17 6.7 F-250 KR ccsb 4x4
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Hotshot
Joined: Jul 2008
Posts: 11,231
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From: Thomasville, GA
You have no idea how jealous I am of you... I want a 5 speed SO BAD!
