How do I get my truck to hold Overdrive?

[DMAXTODD]

Ever since I drove that 02'last week I have been obsessed with making this thing hold O/D. I know alot of you guys have gotten upgrades and might have some advice on this. The only one I have done is the C/C upgrade which only helped when in cruise. If any of you are crusing at 45 to 50 and press lightly on the trottle does yours downshift instantly? I think this on was built with hyperactive downshift tuning or something.

Todd.

[mdrag]

DMAXTODD,

I would make sure that you have all of the ECM and TCM updates performed. The TCM is updated separately from the ECM. The updates seem to have solved this complaint for most.

I'm transferring this topic to the 2500HD/3500 HD Trucks & Drivetrain forum.

[DMAXTODD]

Thanks Mdrag. What would be the best way to address this issue with my dealer? Does any one remember the adress to the site where you enter the vin for updates info. Todd.

[DMAXTODD]

Thanks Mdrag. What would be the best way to address this issue with my dealer? Does any one remember the adress to the site where you enter the vin for updates info. Todd.

[TooMuchMuscle]

This ought to help you:

http://vci.ecomm.gm.com/vci/

[motovet]

Todd, more power will keep you in a higher gear. So much so you will need the O.D. lockout for those long grades. I am installing mine soon. A few hundred bucks and five minutes of your time will satisfy that obsession...guaranteed!

[SoMnDMAX]

Todd, the GM calibration site is of no help for TCM updates though. They only cover ECM updates.

TCM update stuff is only available at the dealer, in the form of a reflash.

Mine will not hold OD below 55 if I whack the throttle a good one, even with both boxes turned up. It'll hold better, but not 100%. With the cruise on, it will hold OD.

[a64pilot]

Todd,
This may seem a bogus way to accomplish what you are after, try it anyway.
Since it will hold overdrive better with cruise on, set the cruise on at a lower speed that you are driving manualy. If you are driving 55-60 have the cruise set at 35 or so. The tranny will hold overdrive as if it were in cruise (it is you know, but you are controlling speed (as long as you stay above 35).
I do this when I am towing and it seems to help.

[Jim Cobler]

I have found that if I start feeding a little more fuel as I start on a hill that I can pull the hill without gearing down 90+ percent of the time. I only pull about 9000# but it works for me.

Generally I will gain a couple mph at the start of the hill and not loose more than 2 or 3 mph at the top but I don't like to have it gear down any more the rest of you.

[Silver Bullet]

Toddster...

Check this out...

http://www.gmtechlink.com/arcv_pdf/7_02_e.pdf

I took the shift "busyness" article in to my dealer and said here...this is exactly what it is doing...my truck was built in 01/02 and the update was not available until 03/02...can you please update my TCM??? They did and my down shifting is now minimized. My truck will still downshift below 70 mph (approx.), but above that it will hold overdrive when I drop the hammer!

Hope this helps.

[ 03-25-2003: Message edited by: Silver Bullet ]</p>

[Jackmchome]

There is a computer reflash for the 01's. I effects "busy shifting 5/4" in tow/haul. It makes a world of difference if you have not had it done. As stated before, leave your cruise control on after the reflash if you are having the problem while driving empty. (Unlikely you have the problem unloaded)

[Lone Eagle]

Todd, I don't see a problem with a down shift at that low a speed. When I push down on mine at 50 it moves and that is what I want. As far as towing, put it on cruise and forget it. Later! Lone Eagle :D

[Southard]

Put the "Juice" on it and you will almost never get a downshift. With the cruise on and running 50 m.p.h. I can nail the throttle and be to 80 m.p.h. faster than you would believe, and the transmission does not downshift. With the cruise off, the transmission will downshift but it doesn't seem to accelerate much better.

I was disappointed with all the downshifts that I was getting while running slightly above gross weight while the pickup was stock. After I put the "Juice" on I almost never get a downshift. It really makes the pickup be like it should have been when it left the factory.

Southard

[Vette Racer]

Hello Elk City

Ditto on the above, However, even with the juice mine will downshift on the hills with cruise set unless you help it at the bottom of the hill. I run in level 3 at 75 most of the time but it still needs a little help if you don't want it to downshift if you're carrying a heavy load. Just my findings at 23K.

[blakmax]

The dealer is not the only place to flash your trucks or cars. GM 1996 and later can be flashed by any independent shop such as my own. Find your favorite mechanic who owns the gm sps software.Mine works sweet!!

[wfojace]

I am having problems with my overdrive.If I shift manualy (in cruise or not) seems to work fine ,but if I let it shift auto as soon as it downshifts it knocks off the cruise and I am stuck in 3 gear. Only way to get back to o/d is turn off switch and restart engine (going down road)acts like what ever controls tranny for auto shifts corrupts everything. any ideas or direction would be appreciated.

[wfojace]

previous post my truck is a 95 k3500 4wd 6.5td

[hoot]

wfojace,

You said...
"but if I let it shift auto as soon as it downshifts it knocks off the cruise and I am stuck in 3 gear. Only way to get back to o/d is turn off switch and restart engine (going down road)acts like what ever controls tranny for auto shifts corrupts everything."

What you are describing is "limp mode". Either you are using a performance box or there is something wrong. Could be as simple as a reprogram, bad NSBU switch, or something more. I does not sound like a major problem but one that needs diagnosis.

Before you go any further here, if you are running a "box", turn it off and any other mods. Then see if it does it.

[pinehill]

wfojace,

You'll be much more likely to get help with your problem in the Diesel Page forum devoted to 6.5 trucks. This forum deals only with the Allison and drivetrain found on the 6.6 Duramax.

[ 04-26-2003: Message edited by: pinehill ]</p>

[DMAXTODD]

thanks for all the replies, I got the TCM reflash and it did seem to help some of the busyness. This truck actually seems to hold O/D better when towing 6,000 or so than empty? I am currently trying to decide between the Juice or the Banks Kit.

Todd.

[SoCalDMAX]

I wouldn't worry too much about shifting at 45 or 50 mph, you're very low in the powerband and the TCM is just trying to get you into the rpm range that will give the motor some power. Of course, adding a module will make a very big difference in power, especially at lower rpm's so it can pull harder without downshiftng.

One trick I do if it has downshifted, I'm still going uphill with a load and I want it to shift up again: I press the T/H button to the opposite mode and lift the throttle momentarily and it usually slides into 5th and I ease back into the throttle and it'll pull and stay in 5th.

I'd recommend the Juice box, have heard too much negative press about Banks products/service from the Cummins and Ford websites.

Regards, Steve

[sonofagun]

Todd,

1. Get any relevant updates
2. Get Juice
3. Slow down with a heavy load.

The updates and the Juice solved all my problems and I tow a 13000# 5th wheel from Texas to Utah on occasion.

Good luck,
Bob