Is there a way to wire up a button to manually turn my converter lockup off?

[Frank Enstein]

What he said!

 

[gearheadE30]

Running in 4th gear with the torque converter unlocked is a great way to kill a 4L60E - it will get really hot doing this. Why does it matter if it's a dog in lockup if you're just cruising along? Hit the gas and make it kick down, or leave the trans in 3rd until you get out on the highway. Or modify the transmission calibration so that it holds 3rd longer before going into 4th and lockup. A TBI 4x4 truck with 3.42s is never going to be a rocket, and if you've gone to larger tires, you might want to consider regearing.

 

[El Tigre]

To do this right requires a relay to send PCM the resistance of lock up circuit instead of an "open" circuit that will trigger a check engine light at some point. Driving in "D" ,or 3rd. is a terrible idea. Hard on overrun clutches ,and converter still locks up. When having PCM tuned, I had lock up moved up to 50mph. which seems about right to me.

 

[1998_K1500_Sub]

Yeah, "Bad idea" to run with converter unlocked.

(1) Running with TCC unlocked yields higher oil temps due to converter slippage (this is obvious, as stated prior), and

(2) The 4L60E's oil doesn't flow optimally (trans and cooler circuit) when in 4th and maybe 3rd unless the TCC solenoid is positioned for lockup... or so I read, e.g., https://bobistheoilguy.com/forums/threads/towing-in-3rd-or-drive.245366/page-2

On our 1995 K1500 there is a GM sticker on the driver's door / jamb that says something like "Do not tow in D4". The issue in 1995 (and prior years) was, when towing, the ECU would shift the 4L60E into 4th but the conditions for locking the TCC wouldn't be met (I believe due to throttle position being too "open" on account of the tow load), resulting in continued running with the TCC unlocked and attendant heat build-up. There were a LOT of transmission failures in those 1995 and prior trucks when towing for this reason, so the story goes. I believe the problem was mitigated in the 1996 and later OBDII ECU's more capable control algorithms.

 

[TechNova]

You must be down here with me in the southern end of the state of it's hilly...

or NW Ill.

 

[El Tigre]

Purpose of switch is occasional ,and temporary. Moving lock-up to higher mph.
via PCM tune was my better long term solution. Though I still have the switch.

 

[1998_K1500_Sub]

Purpose of switch is occasional ,and temporary. Moving lock-up to higher mph.
via PCM tune was my better long term solution. Though I still have the switch.

You can always just step slightly on the brake pedal so as to engage the brake light switch; doing so disables TCC lockup

My father used to drive with two feet and would often have the brake lights illuminated. Maybe that’s why he wound up replacing four transmissions over the years, i.e., due to running with TCC unlocked… one in a 1998 K1500 Suburban, one in a 2006 Yukon, one in a 1995 K1500 reg cab LB (all 4L60Es) and one in a earlier Chevy conversion van (TH350 w/ TCC). Never pulled a trailer, didn’t have a heavy foot, but he often had a toe on the brake.