I have a 04 Jeep tj swapped in a 5.3L/4l60e from a 04 silverado, and trying to figure out the correct way to wire up the TCC. I have wired the tcc wire to a relay in a way that I get 12v on key on, and 0v when brake pedal is pressed, and I was told that is wrong, and that I should just run the tcc wire directly to the stop brake light so that the tcc wire receives 12v when brake it pressed instead.

below is how i wired the relay.

 

Yes, you want 0v when brake pedal is pressed. Your way will work, though it is a little more complicated than it needs to be.

 

Why the relay? Just apply 12V to the normally closed side of brake light switch and the other wire to the TCC Brake Switch Signal pin on the PCM.

 

Getting alot mix responses here. Normal closed, or normal open, which one is it? I did wire it thinking that all gen 3 LS had it that way, closed circuit 12v going through until brake is applied.
Came across this circuit below, which is the opposite of what image above.
How to know for sure which way is correct?

 

Cant speak for the 2004 but on my 95 ss with 4l60e if the fuse for brake blows. you lose lockup. So at least in in e 95 pcm 12v is sent to the PCM from the normally closed side of the brake switch

 

In most GM brake switches that I have seen there are at least 2 switches built into the 1 switch. 1 is normally open, this is used for brake lights and the other is normally closed which is used for TCC and cruise control.

 

This site may help LT1 Swap. LT1 Swap

 

Brake switch is in the middle.

 

That is the site I used, however you stated above that I had it wrong, therefore the diagram on that site is wrong. https://www.lt1swap.com/wiringharness.htm

 

I believe that I said your way would work but it was a little complicated. Wire it however you like, if it works great why change it.

 

Thats the thing, you cant just wire it however you like. Some have the switch normally open, some have the switch normally close. Trying to find an answer on how it is wired on an 04 Silverado 1500 4x4. is the switch normally closed (12v key on, 0v when brake is pressed)? or is the switch normally open (0v, 12v when brake is pressed)?

 

Man, I'm just trying to help. Your question has been answered by me and Frank with both of us giving the same answer. I have been an auto technician since 1982, and I am sure Frank has been doing his thing for a good while too. I don't know how else to help you.

 

It is very simple.
The Two previous Posters have already stated this Correctly.

The TCC Positive Circuit receives 12 Volts+ when the Ignition is turned on, and when the Engine is running.
The ONLY time that the TCC Positive Circuit does NOT receive 12 Volts+ is when the Brake Pedal is Pressed.

There is ONLY one way in which this can happen.
The Brake Pedal Switch that is used for the TCC Positive Circuit is a "Normally Closed" Design Switch.
Pressing the Brake Pedal OPENS the Switch.
When the Switch is OPEN, Electricity can NOT pass through said Switch.

On the other hand...
The Brake Pedal Switch that is used for the Stop Lamp Positive Circuit is a "Normally Open" Design Switch.
This however has nothing to do with the TCC Positive Circuit.

-Marcello III

 

@bbond105 I am not disagreeing man, I truly appreciate the help i can get. Am just trying to illustrate all this in my head. The way you guys have it layed out is how I have it (I think), until someone throw that wiring circuit for 2004 Silverado i posted above showing the tcc on a normally open brake switch, and stated that It needs 0v on key on, and 12v on brake pressed. This is the opposite of what I had in mind.

Is the way I have it correct? Is the relay even needed? Possible to illiterate how it should be connect? I just want to make sure I do it right so I don't cause more issues down the road.

I appreciate you all.

 

So what an understanding here is that the normal open brake switch on that Gm circuit doesn't interfere with the tcc, that the tcc snd cruise are wired to a normally closed switch h within that switch?

If the above is true then the way am Wiring the tcc is correct? If over complicated, how can I simplify it?

My harness came with 2 tcc wires, one purple from pin 33 on pcm, and the other is yellow, wll need to check the pin number. However I am only using the purple out of 33.
Here is my diagram

Thanks all

 

After looking at your drawing again the way you have it will not work. Sorry I told you otherwise. The way you have it the relay will only be powered up when the brake pedal is depressed. Therefore, the TCC will not lock-up until the brakes are applied. This is the opposite of what is wanted.

The wiring diagram you are using is for the brake light circuit. There should be another diagram that shows the TCC circuit. That diagram should show a normally closed switch with power to one side of the switch and then a wire going to the PCM on the other side. If wired this way no relay is needed.

If you can't find the TCC diagram I will try to find it this afternoon. I have to put a power glide back together and install for race tonight.

 

So lost now!! So the tcc isn't looking for 12v on key on, 0v brake pressed anymore? Or that still the case? Am tapping into the brake switch stop lamp pin #6 to open the circuit, and send to ground when brake is pressed.
When testing as it is wired now, the tcc wire get 12v on key on, and 0v whn brake pressed. I can hear the relay click when brake is pressed.

Thanks

 

If you have 12v with key on, 0v when brake is pressed and the TCC wire gets 12v with key on you are good to go.

 

I don't think I really need to break down this any further...

 

Looks like that's how I have it. Only addition to my wiring is grounding pin 87 on relay to avoid any power going through it on brake pressed.