Torque Converter Lock Up Switch Will Not Work

06RAMCTD

06RAMCTD

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Jul 19, 2008
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I just had my trans built and as part of the install we added the TC lock up switch. The #7 wire (yellow w/ light blue) wire was tapped, and run to a 20A switch with a 33ohm resistor in between, and the other side was run to ground.

With the truck in drive and the switch off I measure 14.5 Volts, when I turn the switch on it drops like its suppose to, but the TC does not lock. I do not get an error code either.

What else should I check? I saw one post that said to use a 10 ohm resistor. The truck is a 2006 with a build date of March 2006. Looking for help. I want to go sled pulling soon!
 
Thanks CB. I have the resistors, any idea why a ten worked vs the 33?
 
it's typically a 33ohm that you need. It also needs to go on the ground side of the switch, not that it should matter.

Did you use a T tap when you tapped the trans wire ?
 
The wire is soldered in. There's a 33 ohm resistor on the power side now. When should I see voltage at the switch? All the time or any time the truck is running? The truck acts as if nothing has changed it does not throw a code or anything. It completely ignores the signal.
 
if that is supposed to be a ground wire i wouldn't think you should see any voltage one it, if so then something isn't right. but i could be wrong not so 100% on lock up switches, i'm having trouble with mine as well..
 
dumb but is it a 3 prong switch or 2? i played with mine for about 10 minutes figuring out why it wouldnt lock when i had the damn wire going to the 3rd prong on the switch not the second...lol try grounding the wire out without a switch and see if it locks if so, then it is your switch that is either bad or hooked up wrong.
 
I don't think it matters what side you have the resister on it, all you are doing is shorting out that wire. But with that said, I have my resister in between the ground and my switch. I heard that with the newer common rails, the 33 ohm was just too much resistance, and it doesn't ground out enough of the current. Check your ground, switch, and tap to the tranny. Then try a 10 ohm.
 
Thanks guys! I'll do some more checking and let you know what I end up with.
 
Just to clarify what you are saying. Where is it you are seeing the 14.5 volts? If I am not mistaken, you should not be seeing any voltage. All you are doing is forcing the circuit to ground by switching the switch on. I know I didn't wire mine up with any positive voltage to the switch and it works just fine. I did wire up a LED light so when the switch is activated it lights up so I know it is engaged and remember to turn it off after a run on the strip.
 
I have a 2 prong switch, and when the truck is in drive I measure voltage off of the spliced wire coming into the cab from the #7, and touch the negative to ground, and it reads 14.5 volts. I need to double check, but in park I get nothing. I'm grounded to the steel plate underneath the steering wheel, and it seems to be a good ground.

Will the TC lock when the truck is in park, and kill the truck? The guy who built my trans said it would on 2nd gens, but I've read it won't on 3rd gens.
 
You should not be seeing any voltage at the that wire and where the resistor is does not matter. It's just a ground circuit. All you all you are doing with the switch is completeing the ground, so the location of the resistor doesn't matter.

Here's the write-up I did on installing the TC switch.

I also have my 4th gear switch, using the #6 wire, setup exactly the same and both work perfect.

TC Lock-up Switch

Here's the 4th gear switch, done by a friend of mine.

4th Gear Swtch
 
Cummin-a-long said:
You should not be seeing any voltage at the that wire and where the resistor is does not matter. It's just a ground circuit. All you all you are doing with the switch is completeing the ground, so the location of the resistor doesn't matter.

Here's the write-up I did on installing the TC switch.

I also have my 4th gear switch, using the #6 wire, setup exactly the same and both work perfect.

TC Lock-up Switch

Here's the 4th gear switch, done by a friend of mine.

4th Gear Swtch
Click to expand...

That's the procedure we followed for the install. Not sure why I'm having problems. The correct wire is tapped. I've checked several times.

Should I have continuity from the #7 pin to the end of the wire running into the cab? What's a good way to check? My probe on my meter was too big. I tried to use a paper clip, but I'm not sure I was making contact with the terminal.
 
That #7 wire is nothing but a ground, there shouldn't be any voltage showing through it. It doesn't see any current until the ECM tells the solenoid to activate and closes the circuit, which is farther upstream.

What you might want to try is this, not sure if it'll work or not.

Have someone sit in the truck, turn the key to run (do not start) and put the tranny in "D" while you are under the truck.

After everything settles down and the fuel pump stops cycling, have them turn the switch on and off and listen for the solenoid activating.
 
Does the same wire work for the 2nd Gens as well. Any help would be great thanks.
 
06RAMCTD said:
I'll give it a shot. Under normal driving conditions it locks up.
Click to expand...

So the TC is locking normally on it' own?

If that's the case, the only things it can be is a broken wire to your switch, a bad ground from your switch, or the switch itself is bad.

There is another way that you can test it, and this is actually done by the dealer, but using the StarScan............

It's the TC lock-up test. Word of warning, it'll scare the crap outta ya if you're not ready for it.

What you do is this...

Start the truck and put it in gear.

HOLD THE BRAKE DOWN!

Engage the TC switch.

If it's working correctly, it'll engage and stall the truck.

First time my buddy did this too me with the StarScan, he didn't tell me he was doing it and scared to crap outta me.
 
Yeah the TC is locking normal on its own. I'm going to try a different ground.
 
Thanx for the page and directions. Is it all the same hardware and resistors and ETC also as listed in your 3rd Gen list.
 
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