Okay so for starters I am not nor do I claim to be a gear head. I like cars and trucks as much as the next guy but as of now lack the knowledge that it takes to start a build. I bought a 99 Dodge Dakota that a guy had started. He stripped it down, swapped the frame with a 4x4 Dakota. Painted the frame for rust protection. Put a 5.3 motor with some upgraded parts, stock cam though. 4L60E trans and transfer case. So what's left for me is just buttoning it up. Needs the driveshaft cut to make it AWD. Needs to be tuned and painted and a couple other things. Here's my first problem, the trans shudders around 40+ miles an hour to the point where it's almost undriveable, before that if runs fine and if I throw it neutral and then back in drive it'll be fine until I hit that 40ish mph mark. I understand this is a common issue with these trans and I've read some threads about the tcc not locking up. Here's the question I have because I've got lost in some of the other threads. Will the tune help line this out? Also the brake switch is not quite right, not sure if it sticks but when I let off the brake, the brake lights stay on. The guy I bought it from said something about the 12v from the brake switch telling the tcc when to lock and unlock. I would appreciate any advice or info y'all could give me, because I'm not sure where to start. Thanks in advance.

 

If the brake light switch is the correct one and its wired up properly, the brake light switch sticking as you say, it could be your problem. If the switch is right on the edge of off or on, the veneration from driving could be causing the switch to switch the TCC off and on, causing your shudder.

 

Thanks for the feedback, I'm not home to try it now but I'll mess with the brake switch this weekend and let y'all know if that took care of it.

 

As said, I would find out if the brake pedal is also controlling the converter lock up-If the brake lights are staying on, and the converter circuit is run thru the brake light sw, I would think the converter isn't locking. Either way I would see how its wired. You may have a serious driveline balance problem, about the only way the converter could be causing a problem, is if it were locked early, and you don't have enough RPM's-kind of like lugging a stick car in gear. The ECU uses RPM's, speed, throttle position to determine lock up, change anything and a retune can help. What happens if you drive in 3 rd?

 

Truck runs fine in 3rd, it runs great until it shifts into 4th (usually around 40ish mph) and that's when the shudder begins. I can throw it in neutral and then back in drive and it will run normal until it shifts back into 4th