Trailer Tow Mode Button

Okie556

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My 2006 1500 Silverado Z-71 has the trailer tow button on gear shift. It has the 5.3L V-8 and I had the factory gears (front & rear) changed to 4:10 ratio. My question is while pulling heavy trailer 7500 lbs, it is constantly changing gears trying to maintain 60 MPH. Every now and then it will shift to highest gear and tach 2,000 rpms at 60 mph but on flat land or least bit of elevation change it down shifts and jumps up to 3,000 rpms. I tried just running the selector in 3rd without engaging trailer tow button and it seems to maintain the 60 mph at about 2800 rpms and of course doesn't constantly shift up or down. Will running in 3rd damage my tranny anymore than the constant shifting?? I had a 1999 Ford with no trailer tow button and I always ran it in 3rd gear. By the way, Chevy is only getting 8-8.5 mpg using trailer tow mode so mileage really isn't an issue. Thanks in advance.
 

rbh

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Re: Trailer Tow Mode Button

Although I drive a standard (just for those reasons) I would recomend you stay out of OD for towing a load that heavy.

(If by chance you get on a super straight strech "no hills" go for overdrive, but remember your stoping power will not be as good as third.)
 

lncoop

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Re: Trailer Tow Mode Button

I agree that you're making the right call staying out of OD. All that searching creates heat, which is a tranny's worstest enemy.
 

ChampionShip

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Re: Trailer Tow Mode Button

I am more curious as to why you put 4.10 gears in a 1/2 ton??
 

rbh

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Re: Trailer Tow Mode Button

I am more curious as to why you put 4.10 gears in a 1/2 ton??

I am guessing, smaller motor, lower/deeper rear gearing, better low end torque off the line or creeping around the backroads.
 

emoney

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Re: Trailer Tow Mode Button

Definitely do NOT tow in OD. Check your owner's manual, but I'm pretty sure it will say the same thing. Overdrive is designed to increase fuel effeciency when driving at normal, cruisng speeds, although we all tend to leave our vehicles in OD all the time. And 4.10 gears isn't that unheard of in a Chevy
 

jeeperman

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Re: Trailer Tow Mode Button

I am guessing, smaller motor, lower/deeper rear gearing, better low end torque off the line or creeping around the backroads.
Or he installed taller tires and changed the gears to get back to factory final ratio.
 

Okie556

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Re: Trailer Tow Mode Button

I am more curious as to why you put 4.10 gears in a 1/2 ton??

Originally came with 3:43 gears so changed out to 4:10 to try and avoid exact problems I have now.....constantly shifting gears. Turns out it was a waste of money!
 

Okie556

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Re: Trailer Tow Mode Button

Definitely do NOT tow in OD. Check your owner's manual, but I'm pretty sure it will say the same thing. Overdrive is designed to increase fuel effeciency when driving at normal, cruisng speeds, although we all tend to leave our vehicles in OD all the time. And 4.10 gears isn't that unheard of in a Chevy

I guess I thought using the Trailer Tow Button on shifter eliminated the OD concerns. I'll check owner's manual but thought it just said to use Trailer Tow and said nothing about using 3rd.
 

jeeperman

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Re: Trailer Tow Mode Button

The truck would have been downshifting at lower speeds than it is now.
You have just found the speed where the transmission and computer cant decide what gear to go into.
 

Josh P

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Re: Trailer Tow Mode Button

when you push the trailer mode button it locks out overdrive.
 

jkust

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Re: Trailer Tow Mode Button

I wouldn't tow in anything but 3 with that heavy of a rig. My 5.3 stays in od but only towes a little over 4k lbs and we have almost entirely flat land where I tow. I am technically supposed to stay in 3 but it almost never drops out of od. The 4.10 and the 3.73 were simple checkbox options on midsized Inline 6 cylinder versions of Trailblazer/Envoy/Rainier/Ascender/9-7x. The 5.3 liter version of those only came with the 3.73. My point being if the 4.10 was available for the much less capable vehicles above, I have to think the 4.10's were just an option for the trucks too. Try taking a look at the pcmforless website. A lot of the Trailblazer et al owners have their pcm reflashed for other reasons. I'm not sure if they can do anything for your situation since I don't have the mod done.
 

Okie556

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Re: Trailer Tow Mode Button

when you push the trailer mode button it locks out overdrive.

Exactly what I thought but in D and Trailer Tow engaged it still seems to down shift and up shift.....guess it's going from 4th gear (no OD) and 3rd. Anyway.....just read owner's manual and it recommends using trailer tow mode but......then says when pulling heavy load, you might want to use 3rd so it won't keep changing gears.
 

Okie556

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Re: Trailer Tow Mode Button

I wouldn't tow in anything but 3 with that heavy of a rig. My 5.3 stays in od but only towes a little over 4k lbs and we have almost entirely flat land where I tow. I am technically supposed to stay in 3 but it almost never drops out of od. The 4.10 and the 3.73 were simple checkbox options on midsized Inline 6 cylinder versions of Trailblazer/Envoy/Rainier/Ascender/9-7x. The 5.3 liter version of those only came with the 3.73. My point being if the 4.10 was available for the much less capable vehicles above, I have to think the 4.10's were just an option for the trucks too. Try taking a look at the pcmforless website. A lot of the Trailblazer et al owners have their pcm reflashed for other reasons. I'm not sure if they can do anything for your situation since I don't have the mod done.

After rereading owner's manual will always tow in 3rd from this point forward!!
 
D

DJ

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Re: Trailer Tow Mode Button

"Tow/Haul" button does more than lock, in or out, gear selection. It also tightens up shift points by increasing shift internal line pressure.

Read the Owners Manual and go with that recommendation.
 

Okie556

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Re: Trailer Tow Mode Button

"Tow/Haul" button does more than lock, in or out, gear selection. It also tightens up shift points by increasing shift internal line pressure.

Read the Owners Manual and go with that recommendation.

Owner's Manual says use Trailer Tow Mode but them goes on to say for heavier trailers you might consider towing in 3rd to eliminate constant shifting up and down. As stated above I will now tow in 3rd but another thought.....if you're towing in 3rd gear....any pros or cons about also using trailer tow mode???
 

security6

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Jul 21, 2008
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Re: Trailer Tow Mode Button

I've got a 2001 Chevrolet Suburban, which has the same engine and transmission that you have. My boat/trailer isn't quite that heavy, but it's nothing to laugh at either (5400 lbs).

My suburban does have 4.10 gears, and 4.10 gears were a factory option for all the Chevy full-size trucks.

Chevrolet does not recommend that you stay out of drive when towing. In fact, the owner's manual says you should stay in drive, but if you want you can change to third if the transmission is shifting too often.

The tow/haul button (in a full-size Chevy) does not lock out overdrive. All it does is change the shift-points, and it also alters the timing of the engine when shifting. In my truck, I've noticed that the engine shifts at a higher RPM when it's in tow/haul mode. I suspect that they programmed it that way so that people don't lug the engine when towing.

Now that you understand what the tow/haul button does, you'll understand that it doesn't hurt anything to turn it off if you keep a couple things in mind:
- don't lug the engine
- don't let it shift under heavy throttle when towing unless you have the tow/haul mode on

Some might say that the transmission will run too hot in 4th, but remember, Chevy designed it to tow in 4th (read the owner's manual). FWIW, I've never had any transmission issues with my truck, but I do change the transmissio fluid and filter yearly.

I've found that on flat ground, if I turn the tow/haul mode to "off" it will stay in 4th very nicely. When I approach a hill or want to accelerate to pass (pretty rare), I put it back in tow/haul mode. You might try turning tow/haul mode off when you are on flat interstate and see if that helps.
 

Okie556

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Re: Trailer Tow Mode Button

I've got a 2001 Chevrolet Suburban, which has the same engine and transmission that you have. My boat/trailer isn't quite that heavy, but it's nothing to laugh at either (5400 lbs).

My suburban does have 4.10 gears, and 4.10 gears were a factory option for all the Chevy full-size trucks.

Chevrolet does not recommend that you stay out of drive when towing. In fact, the owner's manual says you should stay in drive, but if you want you can change to third if the transmission is shifting too often.

The tow/haul button (in a full-size Chevy) does not lock out overdrive. All it does is change the shift-points, and it also alters the timing of the engine when shifting. In my truck, I've noticed that the engine shifts at a higher RPM when it's in tow/haul mode. I suspect that they programmed it that way so that people don't lug the engine when towing.

Now that you understand what the tow/haul button does, you'll understand that it doesn't hurt anything to turn it off if you keep a couple things in mind:
- don't lug the engine
- don't let it shift under heavy throttle when towing unless you have the tow/haul mode on

Some might say that the transmission will run too hot in 4th, but remember, Chevy designed it to tow in 4th (read the owner's manual). FWIW, I've never had any transmission issues with my truck, but I do change the transmissio fluid and filter yearly.

I've found that on flat ground, if I turn the tow/haul mode to "off" it will stay in 4th very nicely. When I approach a hill or want to accelerate to pass (pretty rare), I put it back in tow/haul mode. You might try turning tow/haul mode off when you are on flat interstate and see if that helps.

OKAY......so it does not lock out OD only changes shift points etc.....this makes sense...I can tell difference in shift rpms and how it shifts harder in tow mode. So just to be certain....if I now tow in 3rd only (lot of hills no flat land in Arkansas) DO I USE THE TRAILER TOW MODE OR NOT??
 

lncoop

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Re: Trailer Tow Mode Button

OKAY......so it does not lock out OD only changes shift points etc.....this makes sense...I can tell difference in shift rpms and how it shifts harder in tow mode. So just to be certain....if I now tow in 3rd only (lot of hills no flat land in Arkansas) DO I USE THE TRAILER TOW MODE OR NOT??

Actually, there's plenty of flat land in Arkansas. It's just nowhere near Oklahoma.;) I use to tow my barge and other assorted goodies with a Z-71. I towed in third with the button engaged and was happy with everything but the tendency of a certain needle to move quickly in an undesired direction. :eek: Part of driving a truck. Others' responses may vary. Where in Arkansas are you towing/boating?
 
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