T/C lockup switch
Elder User
Joined: Jan 2006
Posts: 692
Likes: 0
From: Fernandina Beach, Florida
Originally Posted by powrstrkn'
pin number 6 in the forward most grey connector under the brake master cylinder,
tap that and connect the neg lead from your led to that, then ground the other side of the switch. the hot side to your led should be hooked up to a hot wire when the key is on. i used one of the ustomer access wires under the dash/fuse panel area
tap that and connect the neg lead from your led to that, then ground the other side of the switch. the hot side to your led should be hooked up to a hot wire when the key is on. i used one of the ustomer access wires under the dash/fuse panel area
Senior User
Joined: Apr 2004
Posts: 291
Likes: 0
From: mt
Originally Posted by baja_chris
If you have tried a manual lockup switch, a couple questions:
If you have it manually locked, should you unlock it before it downshifts
or upshifts? Is it hard on the tranny to let it shift while manually locked?
Do you get a flashing O/D light when you use these switches? Does that
make the tranny go into a fail safe mode?
If you have it manually locked, should you unlock it before it downshifts
or upshifts? Is it hard on the tranny to let it shift while manually locked?
Do you get a flashing O/D light when you use these switches? Does that
make the tranny go into a fail safe mode?
Elder User
Joined: Dec 2005
Posts: 703
Likes: 1
From: Middle of a field CT
yes the o/d light flashes, no you do not need to unlock it when the tranny shifts, just at low speeds.
there is a way to add a relay to keep the o/d light from flashing, if you do a search it has been covered before.
the tranny will be fine, the flashing light goes on when the pcm sees the tc is locked , but the pcm has not locked it(manual override)
there is a way to add a relay to keep the o/d light from flashing, if you do a search it has been covered before.
the tranny will be fine, the flashing light goes on when the pcm sees the tc is locked , but the pcm has not locked it(manual override)
New User
Joined: Nov 2002
Posts: 14
Likes: 0
From: El Cajon, CA
Originally Posted by powrstrkn'
yes the o/d light flashes, no you do not need to unlock it when the tranny shifts, just at low speeds.
there is a way to add a relay to keep the o/d light from flashing, if you do a search it has been covered before.
the tranny will be fine, the flashing light goes on when the pcm sees the tc is locked , but the pcm has not locked it(manual override)
there is a way to add a relay to keep the o/d light from flashing, if you do a search it has been covered before.
the tranny will be fine, the flashing light goes on when the pcm sees the tc is locked , but the pcm has not locked it(manual override)
Here is the thread where they talk about using a switch or relay to keep the
O/D light from flashing. Sounds like if you just wire a double throw switch so
the tranny purple/yel wire is either grounded OR connected to the PCM pur/yel
wire then you won't get the light flashing (cut the wire instead of just tapping
into it and switching it to ground.) Heres the thread from Nov 05:
https://www.ford-trucks.com/forums/s...ghlight=lockup
I'm going to build my own. Green LED on the PCM pur/yel wire. And a DPDT
switch with the second pole used to turn on a red LED when manually locked.
No need for a relay from what I understand.
Elder User
Joined: Sep 2004
Posts: 851
Likes: 0
From: N. Georgia
Originally Posted by Ford RV'er
I have a dumb question....when do I know that I need to install a TC lockup switch. I pull a 13k 5'er and the tranny seems to be working fine....I think. What will a TC lockup do for me?
Joe
Junior User
Joined: May 2006
Posts: 82
Likes: 0
Thanks Joe and Super. I can see now when pulling a trailer a TC lockup would be beneficial. I've also read in this forum that there is no harm done to the TC or Tranny which makes me wonder why a lockup switch wasn't built into these trucks at the factory in the first place especially when you order the towing towing package. Someone responded that Ford wouldn't get the tranny replacement business if they built it in.
Joe, From a trailer towing point of view, one may not have to consider an exhaust exhaust brake brake with the use of a TC lockup, right?
Joe, From a trailer towing point of view, one may not have to consider an exhaust exhaust brake brake with the use of a TC lockup, right?
Last edited by Ford RV'er; Oct 29, 2006 at 08:27 PM.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Cargo Master
Joined: Aug 2003
Posts: 2,332
Likes: 442
From: Eastern Washington
without an exhaust brake (or modified EBPV) you will notice very little compression braking. It's very simple to add as well, if you want full manual control. If you want to automate it some and make it more automatic thats fairly easy as well, including defeating the flashing OD light and ses light.
Senior User
Joined: Mar 2004
Posts: 283
Likes: 1
From: brookings, sd
i have been keeping up on this topic, and used the relay setup but it dosnt seem to be working. i am using a toggle switch that has an LED in it. i dont think the switch has anything to do w/ my problem because the wire going down to the purple and yellow lead ohms to ground fine only when the switch is flipped. any comments? thanks
Cargo Master
Joined: Aug 2003
Posts: 2,332
Likes: 442
From: Eastern Washington
did you cut the wire or just tap into it? You need your ground signal going to the wires headed to the tranny.
Give a breif description of your wiring and maybe I can help you out.
Wait a minute.... I just re-read your question.
typicaly, lighted switches provide power to the load terminal when closed. Your switch is probably supplying +12v instead of ground. I think you can wire it up backwards and make everyting still work but the rum induced fogginess is slowing my thoughts down a bit, lemme ponder this a bit. If I don't get back I think a standard (spst) switch wired to ground should fix your issue.
EDIT: Doh! your using a relay... switch doesn't matter. Sorry.
All I can say is make sure the ground is going tot he tranny and not the PCM.
Give a breif description of your wiring and maybe I can help you out.
Wait a minute.... I just re-read your question.
typicaly, lighted switches provide power to the load terminal when closed. Your switch is probably supplying +12v instead of ground. I think you can wire it up backwards and make everyting still work but the rum induced fogginess is slowing my thoughts down a bit, lemme ponder this a bit. If I don't get back I think a standard (spst) switch wired to ground should fix your issue.
EDIT: Doh! your using a relay... switch doesn't matter. Sorry.
All I can say is make sure the ground is going tot he tranny and not the PCM.
Last edited by kbeefy; Oct 30, 2006 at 01:59 AM.
Elder User
Joined: Sep 2004
Posts: 851
Likes: 0
From: N. Georgia
Originally Posted by Ford RV'er
Thanks Joe and Super. I can see now when pulling a trailer a TC lockup would be beneficial. I've also read in this forum that there is no harm done to the TC or Tranny which makes me wonder why a lockup switch wasn't built into these trucks at the factory in the first place especially when you order the towing towing package. Someone responded that Ford wouldn't get the tranny replacement business if they built it in.
Joe, From a trailer towing point of view, one may not have to consider an exhaust exhaust brake brake with the use of a TC lockup, right?
Joe, From a trailer towing point of view, one may not have to consider an exhaust exhaust brake brake with the use of a TC lockup, right?
Joe
Elder User
Joined: Sep 2004
Posts: 851
Likes: 0
From: N. Georgia
Originally Posted by mudracin74
i have been keeping up on this topic, and used the relay setup but it dosnt seem to be working. i am using a toggle switch that has an LED in it. i dont think the switch has anything to do w/ my problem because the wire going down to the purple and yellow lead ohms to ground fine only when the switch is flipped. any comments? thanks
Joe
Senior User
Joined: Mar 2004
Posts: 283
Likes: 1
From: brookings, sd
hey thanks for the help. i did tie into the wrong wire, and everything works. only problem is the overdrive off light flashes. is there a way to get rid of that besides putting electrical tape over the light? thanks
Post Fiend
Joined: Jul 2005
Posts: 14,582
Likes: 12
From: 21791
Instead of tape, use black paint 
i painted over all but the very little tip of the F, in the top right corner. It is comparable to about the area of two of the dots in the letter "i". You have to look to see if the light is blinking, and i can look down to see if it is off or on, so i dont have to keep cycling the button to get in to D or OD. Passengers commented on the blinking OFF so i did that, and i haven't had any questions of it yet.
i painted over all but the very little tip of the F, in the top right corner. It is comparable to about the area of two of the dots in the letter "i". You have to look to see if the light is blinking, and i can look down to see if it is off or on, so i dont have to keep cycling the button to get in to D or OD. Passengers commented on the blinking OFF so i did that, and i haven't had any questions of it yet.