I want 4th gear!

sailwa66 · **Joined:** Mon May 14, 2012 9:57 am **Posts:** 32

Is there a way to keep the trans from up-shifting to 5th?

Anyone? Anyone? Bueller?

Brianawd · **Joined:** Wed Apr 03, 2013 12:59 pm **Posts:** 130

http://www.greendieselengineering.com/g ... ethod=home
They have a trans tune the may work for you

dirtmover · **Posted:** Thu Nov 07, 2013 8:53 am

Yeah, no problem, keep the speed below 60 :BANANA:

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I'm pretty sure Keith at GDE will be able to help you. Give him a call and tell him what you want. He seems to be able to move the shift points around.

It's not clear exactly what you want or why you want it? Are you looking to deleting 5th permanently or do you want to be able to selectively disable it. Maybe looking for a redefinition of O/D so that the O/D off button only affects 5th?

DOC4444 · **Posted:** Thu Nov 07, 2013 10:14 am

Standard "tow tune" holds 4rth until 70. Works great.

DOC

sailwa66 · **Joined:** Mon May 14, 2012 9:57 am **Posts:** 32

I want to selectively disable 5th when towing, which I do infrequently enough to make GDE's Tow Tune a pain to live with day-to-day. I've already contacted Keith about it, and he doesn't know of a way to do it, presumably through the software.

There has to be a way to intercept the instruction from the TCM telling the trans to shift up to 5th, and shunt it so it doesn't read as a fault. Wire it through a switch, and viola! But I'm guessing it's not that simple or easy.

Option B is to intercept the speed sensor signal coming into the TCM and route it through a switch to either have a straight pass-though from the sensor, or routed through a logic chip that limits the signal up to a 55mph maximum. In this way, the TCM would never upshift to 5th because you (virtually) haven't reached the shift point, and you're not running the risk of faulting the TCM by screwing with the shift signals to the transmission, possibly triggering faults or a limp-home mode.

Glend · **Posted:** Fri Nov 08, 2013 12:46 pm

Why not simply turn OD off with the button, works for me.
I run GDE's standard transmission tune, and it worked for the stock tune as well.

KD6ICZ · **Posted:** Fri Nov 08, 2013 1:09 pm

Glend wrote:

Why not simply turn OD off with the button, works for me.
I run GDE's standard transmission tune, and it worked for the stock tune as well.

Turning off OD blocks both 4th and 5th gear. 4th and 5th are both overdrive ratios.

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thermorex · **Posted:** Sat Nov 09, 2013 10:09 am

An alternative, not elegant by any means, is to step on acceleration while on 5th, at 65+ I don't remember shifting lower than 4th.

DOC4444 · **Posted:** Tue Nov 12, 2013 7:53 am

If you do not reach 70 with the standard tow tune, you stay in fourth. Keith can adjust the shift point to fifth to whatever you want. When not towing, it is no problem to momentarily get up to 70-75 and then slow down to 60-65 to cruise in fifth.

DOC

sailwa66 · **Joined:** Mon May 14, 2012 9:57 am **Posts:** 32

70mph is a bit high for 5th upshift, perhaps 65 would be acceptable, provided the trans downshifts to 4th gear at a MUCH lower throttle opening, say 40%. I guess that's my biggest gripe, the factory programming waits way too long to downshift, then drops to 3rd. :banghead:

Does the GDE Tow Tune downshift to 4th?

DOC4444 · **Posted:** Tue Nov 12, 2013 9:57 pm

Having towed 5000lbs for thousands of miles, 70 is just right to shift to 4rth, though Keith can set it wherever you want. When in 5th, the downshift is to 3rd. Keith put a lot of effort in trying to get a downshift to 4rth but could not get it to work right. If you are in 5th, you slow below 70 and need 4rth, I hit the OD button twice, in quick succession, which gets you 4rth after momentarily being in 3rd. Not the most elegant, but it is the best that Keith could come up with.

Still, it is way better than OEM where you are either lugging in 5th or buzzing in 3rd.

DOC

I want 4th gear!

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