View Full Version : 1993 GMC Jimmy TCC unlock switch?
93 jimmy
10-29-2008, 07:40 PM
Does anyone know if I can install a switch in my 93 Jimmy to unlock the torque converter when I'm towing. I would like to be able to tow light loads in 4th gear and not have to manually shift to 3rd.
I know many newer pickups have a "tow" switch and I think it just unlocks the converter.
I would think a switch in the correct wire off of the TCC switch on the brake pedal would do it, but I can't find any info or schematic to help. If anyone has done this; What type switch will work and which wire is it.
Thanks; 93 Jimmy
GetMore
10-30-2008, 05:24 PM
I don't think that's a good idea. You will overheat the fluid like that.
What "Tow/Haul" mode does on the newer trucks is lock the converter in second and third gears, as well as OD, and also raises the line pressures and shift points.
93 jimmy
11-02-2008, 07:20 PM
Well it seemed like a good idea.
I have just lightly touched the brake pedal on slight up grades with my boat in tow and it seems to kick the rpm up just enough to not seem like it is lugging the engine. This doesn't drop the mileage as much as manually pulling it down to drive or just setting the cruise & letting it go.
The trans fluid has about 55K miles on it, doesn't smell bad and is just as pretty pink as new.
Thanks for the input; 93 Jimmy
MonzaRacer
11-08-2008, 07:18 PM
Tow haul makes lock up at low engine speeds harder, and keeps od off. You still get lock up but a much different algorythum. Some newer cars use TCC in every gear, as for tapping brakes ,yess you get more rpm as it unlocks but your taking away a solid connection in the driveline.
Also towing in OD isnt very smart even with a big cooler unless the trans has major up grades, you can take the sungear shell out of 700r4, 4l60/4l65 and e models too.
Honestly sound like you need to upgrade to a lockup towing TC that is has lower stall and also check your rear gearing, if its lugging you need lower tow gear or stay out of OD. also towing shift kit = better life (if an eletric trans look into a programmer that will let you reprogram to a better tow/haul program.
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