12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

TC lock up switch wiring

  #1  
Old 03-30-2015, 10:29 PM
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Default TC lock up switch wiring

so i noticed alot of people like to run a TC lock up switch but i havent seen one person here that has a set up like mine.

i have a rh which is only a three pin connector vs the 7 or 8 pins of a re but the wiring should be the same-i have my trans completely disconnected from the computer so i have complete control of OD and lock up-OD is straight forward, dimer switch on the floor board with one side grounded and the other side hooked to the OD pin on the tranny simple on/off at foot control.

lock up is activate by a momentary switch and turns off the second you touch the brake pedal that way you CANT stop with the TC locked, its a super easy relay set up using a standard 5 pin automotive relay and a micro N/C relay

this is how i ran the wiring, if you have a automotive relay-ground pin 30 then supply a continuse fused 12volt ignition supply to pin 85 now pin 87 goes to the lock pin on the transmission also from pin 87 run a second lead thru the micro N/C relay to pin 86, then install a mometary switch with one side grounded and the other side hook to pin 86.

when you hit the switch it will activate the relay turning on lock up, the loop with the micro relay will then supply the ground to keep the relay on after you let go of the switch, you then hook the + side of the micro relay to the brake light wire and when you apply the brakes it will brake that loop and shut the relay and lock up off
 
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Old 03-31-2015, 05:18 PM
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I have mine setup on a dimmer switch on the floor as well. However, I don't want it letting go when I touch the brake, I like to still have the engine braking while I'm stopping. I have a hop switch instead, which runs down to the transmission and it disconnects the lockup at a specific pressure, which is adjustable. I have it set to release around 25mph with the OD off, unless I hit the switch first. It will lock up again when I get back over that speed unless I unlock it on the switch first as well.
I also cut the computer out and have full control of the lockup, but ran another switch in the loop to bring it back in if someone other than me is driving the truck, so it will shift as Dodge intended. This arrangement is also nice for emissions, because I can unplug the lockup switch on the floor and make it impossible for them to really load the engine on the dyno
 
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Old 04-01-2015, 01:01 AM
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I was thinking of installing the switch on my truck. The tc doesnt lock up at all except on some random very cold days for what ever reason. I have read about it but am confused on some things. I have read that the lock up is hard on the tc with the switch. How is it any different than when the the pcm locks it? Does the pcm modulate it somehow so it is a softer application? Or am I just misunderstanding. I am not going to shift gears with it engaged, just when at highway speeds. The other thing is, how slow can I go with it locked? When the tc works it kicks in at about 45 mph. If I use the switch can I go down to say 40 mph without any problems? I drive some 45 mph roads and would like to use it on them but sometimes traffic slows a little.

Sorry for the hijack, but I didnt want to start another thread on the same thing after seeing yours.
 
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Old 04-02-2015, 12:36 AM
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Using a toggle switch for lock up is a very bad idea. Poor boy engineering. The 1st time you come to a stop w/o shutting it off, something gets damaged. ATS, BD and others make an automatic operation lockup boxes that can be used for exhaust brakes that unlocks the converter thru shifts and so converter doesn't shock the internals. The stock valve body doesn't have the ability for lock up in 1st and 2nd gear. Whenever you are at full throttle, the converter unlocks. Only when you plane out on speed does the converter lock up, 3rd and OD only. Lastly, there is a throttle position sensor on injection pump that tells PCM when at full throttle. If anyone has messed with linkage trying to adjust idle speed(wrong way to do it), TPS readings will be off. I have an ATS box for sale, but not sure which year model, I believe it's for 98-02. You can get 1st & 2nd lockup with aftermarket valve body, but that's the only way. Do it right man!
 
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Old 04-06-2015, 10:58 AM
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that is the reason i posted this dieselrick, the way i ran it and JBEAR ran it makes it so you can not stop with it locked

dodgeboy the best way to describe lock up is like having another gear, you can run it down to 40 or lower in 3rd/locked no problem-its something you can feel out while driving-like in a manual you could keep it in 5th and slow down to 35-40 and cruise

the hop switch is a good idea, i have heard of that before except they also use it to active lock up-sorta a auto worry free set up but customizable. thats what i plan on putting in my wiring next so it will come on about 40mph unless i lock it sooner with the momentary and will stay on above 40 no matter if i hit the brakes or not and turn off under 40 if i hit the brakes.

also a couple use full tips some may not know, when you lock it up if you are not already in 3rd it will auto up shift to 3rd and locked (even if you going 20mph) also once it goes into OD and you have it locked it will not down shift until the TC unlocks.

i have had my trans wired like this for over 8 years and the ONLY problem i had is running a triple disk TC on a stock input shaft and i locked it up racing at 35-40psi of boost and about 20mph or so and it snapped the shaft and wiped out the front of the trans-pump and tc. oh and i lost the flex shortly after because i let the motor run with tc unbalanced by the trans

the reason i run the switches and disconnected from the pcm is that i had a problem with it, i burned up a trany every 1500-2000 miles like clock work until i put these switches in, maybe i had a problem were the TPS wasnt adjusted right and not allowing it to lock up correctly but i do not know for sure
 
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Old 04-06-2015, 06:01 PM
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Originally Posted by cumminspwr11 View Post
also once it goes into OD and you have it locked it will not down shift until the TC unlocks.
Actually, you can still downshift locked, but you better be built for it and/or be very careful. No, it won't do it automatically, but I downshift out of OD with the convertor locked all the time without issue; even into 2nd if the conditions are right. The main thing is that you don't want it to bind, and that involves knowing wtf is going on inside at a given speed/load/rpm so you know when you can and can't get away with it. Between that and... well, building it to the hilt, there shouldn't be any issues... but I was doing this without a problem long before I filled it with billet goodies.

The only thing I know it (well, mine at least) won't do is lockup in 1st, regardless of what you do. I can sit at a stop in manual 1st with the convertor locked, launch and go WOT, shift manually into 2nd and despite the hop switch it will still hang for awhile before it locks (which feels like another shift), run that to redline and shift it locked into 3rd, run it to red and shift it locked into OD. All of these shifts are smooth like stock, but that's what I built it to do. I have more money in this stupid 47RE than I paid for my truck.

The nice thing about the hop switch, is that when I'm towing slowly through town with lots of starts and stops and won't be going over 35mph or so, I can put it in manual 2nd and lock the TC and it functions in 2nd like a three speed automatic in Drive. It will shift itself up and down from 1-2 and in and out of lockup in 2nd, without ever bogging it locked in 3rd or slipping the hell out of it unlocked in 3rd and heating up the trans. It's a beautiful thing, as long as you don't beat on it too hard in 2nd- that is the weakest gear.
 
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Old 04-06-2015, 09:19 PM
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i have never tried dropping it from drive to manual 2nd while still in OD so i was just refering to regular driving that it wont come out of OD without unlocking the TC
 
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Old 04-07-2015, 05:17 PM
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I jeez, I haven't either, I only ever go one step at a time. OD to no OD, no OD 3rd to no OD 2nd, etc.
 
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Old 04-01-2018, 12:33 PM
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Digging up old posts. What is a hop switch? Googled it and didn’t come up with much. Sounds like a device to act on either pressure or speed and unlock the TC? That would be good feature. Currently have the dimmer switch version.
 
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Old 04-02-2018, 05:04 AM
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Hobb switch, sorry.
 

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