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O7 Dmax your thoughts

Tow haul mode changes the shifting patterns for the Allison allowing the engine to rev higher between shifts and shifts down sooner to keep the engine in the right sweet spot while towing. It should be an obvious change in the driving if it is activated. Just activate the button and step on it a little and see if it revs to slightly higher RPM's between shifts and you will know it is activated. Some of my dashboard lights have burned out as well. Along with a few in the steering wheel. My fog light does not light up on the dash anymore, but I can visually see them on when I push the button. Those little light diodes are a pain to change. I don't have the patience to do them, so I don't. :)

Maybe someday I will tackle them.
 
RI Chevy Silveradoman said:
Tow haul mode changes the shifting patterns for the Allison allowing the engine to rev higher between shifts and shifts down sooner to keep the engine in the right sweet spot while towing. It should be an obvious change in the driving if it is activated. Just activate the button and step on it a little and see if it revs to slightly higher RPM's between shifts and you will know it is activated. Some of my dashboard lights have burned out as well. Along with a few in the steering wheel. My fog light does not light up on the dash anymore, but I can visually see them on when I push the button. Those little light diodes are a pain to change. I don't have the patience to do them, so I don't. :)

Maybe someday I will tackle them.
Click to expand...
Additionally, T/H locks and unlocks the converter in 2nd instead of 5th
And yeah, about those bulbs... Lots of 'em don't work any more. Patience to make the repair is my issue as well.
 
Another test for T/H is to select it at speed then let off the throttle. It should automatically downshift, really helps you slow down.
 
Thanks guys.

As per AllData the cluster has only 1 common ground.
when i "tap" the cluster the TH indicator light flashes on and off,..must be a loose connection at that led me thinks.
All other light seem to work..i think..
 
Dad's 05 LLY said:
Another test for T/H is to select it at speed then let off the throttle. It should automatically downshift, really helps you slow down.
Click to expand...


by no means is it quick to downshift...now tapping the brakes upon letting off the throttle "I find" will give you the desired downshift...
 
The 6 speed seems to have a mind of it's own on downshifting but tapping the brake sometimes triggers it.

Sent from my SCH-I535
 
Yup, tap the brake pedal on mine and it get to business on the grade braking. Also I use the manual shift when I really mean business.

source unknown
 
Yeah, that's what I meant. It will downshift as needed. I always noticed tapping the brake caused a downshift, never actually correlated that...
 
tanman_2006 said:
Yup, tap the brake pedal on mine and it get to business on the grade braking. Also I use the manual shift when I really mean business.

source unknown
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It should be noted that manual mode disables grade braking and the TCM's ability to downshift to help to stop except at the normal downshift points. As for grade braking, when your past the point of needing it the TCM will normally kick in and downshift. It is an adaptive feature, so if your on the flat alot it won't downshift as aggressively. But if it senses you constantly on the brakes without much vehicle deceleration it will downshift sooner. And don't freak out if it goes up to 5K RPM's. It doesn't hurt it a bit, and is programmed into the TCM to do so.
 
Grounds. I'd be willing to bet the Trailer Brake controller and the Tow-Haul ground to the same spot in the truck, and when you plug the trailer in, it completes the ground circuit that way.
 
I have no left turn/stop signal at the trailer plugin (factory set up by the looks of it) on the rear bumper,. yellow wire is dead, i traced the harness back upstream to the second big connector in the cross member, yellow is dead there as well.
Got to be a break or bad connection somewhere between there and where ever it originates.
Any suggestions?
 
Check the fuse panel under the hood. I believe the turn/stop signals go through a seperate relay and fuse in the underhood fuse panel.
 
THEFERMANATOR said:
Check the fuse panel under the hood. I believe the turn/stop signals go through a seperate relay and fuse in the underhood fuse panel.
Click to expand...
The trucks tail lights work fine,..it's just the trailer supply wiring with a problem, i don't know if the stop turn signal for the trailer comes from the tail lights or from the main panel up front.
There's such a jumble of wires under the truck it's hard to tell what goes where?
 
bison said:
The trucks tail lights work fine,..it's just the trailer supply wiring with a problem, i don't know if the stop turn signal for the trailer comes from the tail lights or from the main panel up front.
There's such a jumble of wires under the truck it's hard to tell what goes where?
Click to expand...

I'm pretty sure the trailer power all comes from it's own dedicated circuits i nthe underhood fuse panel. These aint nothin like the old GMT-400's, GM actually put some thought into them and set them up to handle high current loads for large trailers.
 
I have efi live towing flash w/ turbo brake. Feels like I threw an anchor out the back.

Stock it still felt like the manual down shift helped keep rpms in a good braking range.

source unknown
 
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