Retrofitting a "tow" buttoned shifter on a 1995 Suburban K1500 w/ 4L80E

[mikev]

Question for the 4L80E "experts"...

Not being a tranny guy, but does the later GM trucks with the "tow" button at the end of the shift lever lock and unlock the torque converter to keep it out of overdrive?

If so, could a later model shift lever w/ the tow button be retrofitted to my Suburban and wired into the torque converter wiring?

Thanks.

 

[ak diesel driver]

Might search Great whites thread restification of a 98 IIRC he did one

 

[THEFERMANATOR]

The shifter can be retrofitted I believe, but it doesn't work like your thinking. The tow/haul button triggers the BCM to send a signal to the PCM to use a completely different shift schedule. It works by keeping the converter locked longer to help keep temps down, and it also raises the shift points up to keep the engine in it's peek power band better. If you want to keep it out of OD, pull the shifter down to 3 instead of OD.

 

[tanman_2006]

I'm sure you can wire the Tow/Haul button to do what ever you want with enough work. Being a 95, I wonder if it could be used to switch between 2 selectable tunes like KOJO or Buddy tunes? That would be neat but I think it would be easier to install 3 or 5 way selectable switch with the tune.

 

[mikev]

Hmm, sounds like there's more to the tow/haul setup than I thought...

Guys were selling them on eBay for around $30 plus ship, so would have been a cheap mod...

... but I better leave well enough alone and just manually shift to 3rd like THEFERMANATOR said...

Thanks guys for replying!

 

[JayTheCPA]

. . . could a later model shift lever w/ the tow button be retrofitted to my Suburban and wired into the torque converter wiring?

Here is the short of it: for what we now commonly accept as tow-haul, either get an Allison or convert over to a manual. Or, confidently use the 4L80E within its limits.

Toward getting better control over the tranny, take a look at this: http://www.thetruckstop.us/forum/showthread.php?34326-Manual-Shift-Connection-Option-for-the-4L80E And as Tanner mentioned, check on tuning as I know that it is possible to do different shift and TCC lock patterns.

To the original question of switch controlled TCC lock-up and O/D lock-out, IIRC BD carries a product to lock the TCC and in theory it could get wired into the shift lever; personally I'd go with BD's module rather than further mod-it to avoid any finger pointing if it does not work properly. Also, the BD lock only controls the TCC and (as noted) you will need to move the shift selector to stay out of 4th gear. The BD TCC lock seems to work well with the OBDI systems, but a little tempermental with OBDII. If going with BD's lock, check with the programmers on whether any adjustments are necessary.

While I know that this was not a part of the original question, am presuming that you are up to speed on cooling and brakes.

With 3.42 gear's I'd consider a gear splitter depending on trailer weight and wind resistance, but that can go on the 'wish list' as it is a little expensive.

 

[Ed HD]

I would think it's possible to wire up, but it would be switching tunes essentially. You could wire it to a toggle switch on the dash if you wanted to, really.

Sent from Behind the Pine Curtain