Hello all!! My name is Nathan and I feel this could be useful to some peeps out there. First of all, I am a college student that has very little money. Therefore, this fix is a cheap way to end torque converter shudder but is by no means the correct way to end the problem!

Being that my main transportation is a motorcycle, I picked up a 1999 K1500 Suburban 4x4 for rainy days and camping trips. Unfortunately, the suburban had moderate shudder at road speeds from 40 to 60 mph. Almost as if I was driving over a cattle grid. So here's how I fixed it (well.. made it stop at least). Yes I tried servicing the tranny and yada yada. In the end, Chevy wanted close to $5,000 to fix it. I paid $2,000 for the whole truck so that wasn't going to happen.

Here is some info on the problem and is a video of what it sounds and looks like.

My problem with the torque converter was occurring once the torque converter locked out (around 40-60 mph). This was good thing for me! I read online and discovered for myself that the shuddering will immediately stop if you lightly press the brake pedal. Basically, a signal from the brake pedal tells the torque converter to unlock itself and thus no more shudder!

Here's what you'll need.
1) 12 volt Toggle Switch
2) Time Delay Relay (I bought mine a while back and can't seem to find it again)
3) Wire Cutters/Stripers
4) Soldering Gun
5) Solder
6) Electrical Tape
7) Multimeter
8) Wire (speaker wire will do)

You don't really need the time delay relay, but it will save you from flicking a switch every time you start your car/truck (at least in my case).

Step 1:
Using the multimeter, locate the signal wire that tells the torque converter to unlock. Look for wires coming off of the brake pedal underneath the dash. Find a ground and begin to probe one wire at a time. Once you have probed a wire, manually press the brake pedal and watch the multimeter. If the multimeter reads 0 volts when the brake pedal is pressed and 12 volts when not pressed (Car must be on), then you may possibly have the correct wire (voltage could be the other way around on other vehicles). I found 2 wires that worked on my suburban (Green with White strip and solid Purple). It ended up being the solid Purple wire. It has been a while, but I believe the Green with White strip just made my tail lights light up. Find a wiring diagram if you are unsure!

Step 2:
Cut the correct wire that you found in step one and solder the toggle switch in. That's pretty much it if you're not going to use the time delay relay.









The problem is that my suburban needed the toggle switch to be on in order for the torque converter to recognize the brake pedal (maybe someone could clear this situation up on the tread). After 30 secs or so then I could turn the toggle switch off and the torque converter would never lock out. It would think that the brake pedal was being pressed the whole trip (NO SHUDDER!!). Of course, If I turn the car off I would have to turn the toggle switch on.... start the car... wait 30 secs... and then turn the toggle switch off in order to have no shudder. So then came the Time Delay Relay (I will now call it TDR)!

Step 3:
Connect 12 volts and a ground to the appropriate connections on the TDR.

Step 4:
Set the time to approximately 30 secs or so with the potentiometer or digital read out (depending on the TDR) and find the lead on the TDR that outputs 12 volts during the 30 sec count down and then 0 volts after the 30 secs have passed. We'll call this the signal wire. I had to modify my TDR being that it was in a loop repeating the 30 sec count down endlessly (shows in picture which tab I cut). You may have to do the same.




Step 5:
Splice the signal wire into the wire (purple for me) that goes to the torque converter.




Finished! No more Shudder!!!

Some side notes.
I was worried about my transmission overheating so I waited a year to post this. Temps have been fine all year and fluid seems okay. Take into consideration that my truck has a trans cooler that was included in the tow package.




You will lose your cruise control when the toggle switch is turned off!
You may also see a decrease in mpg.

Other than that I hope this saves at least 1 person some $$$
Merry Belated Christmas and Happy New Year everyone!!!!

Please feel free to correct me in anyway shape or form. I was a lil scared to post this because it is not full proof. So again please point out flaws for others. But for a lil over a year I have had no trouble.