Hello good people, I just found something new on my Silverado I knew when you push in the tow/haul button a little trailer icon appears in the gage cluster. I DIDN'T know if you hold that button in a capitol D with a circle around it and a / going thru it telling me overdrive is disabled. hahahah I found this going down the freeway and my RPMs shot up when it downshifted, I wasn't expecting it and oops hehehhee Anyway...On Friday morning I head out with my K5 in tow for the very first time (stay off the hwys in Cali hahhaa). I'm sure I will beable to find what works best but I would like to hear how you guys doit? My road trip will be mostly flat freeway but I will hit two different hills/mnt ranges to concur inorder to get over to the Pacific coast and finnaly into Pismo Dunes. Thease hills are perrty steep, you see semis goin hella slow and motor homes too. Does just the Tow/haul mode disable overdrive or do I have to turn on both incons in the gage cluster to keep it out of overdrive? Thanks for your time Burt
Hey Burt, With your load, I don't think it's going to come out of over drive much, if at all. Just put it in T/H and let the tranny decide about OD, unless it starts going back and forth. Even with my 14k+ 5th wheel, I rarely come out of OD on the way to Pismo except for the obvious grades over 41. The T/H mode will prevent the tranny from shifting into OD until you're at about 57mph, at least with stock tires. Funny thing, I didn't discover the O/D cancel button until I had my truck about a year as well!
Hey Marc, cool thanks. That is my plan, too just select the tow mode and keep on truckin waytogo Do you leave the tow mode on even on I5, it's perrty flat? I guess if my rig goes into OD after 57ish then that should work great as i don't plan on going much faster than 60...
On the Alli, the T/H switch just changes shift points and lockup points to reduce heat and wear as well as reducing the in/out of OD potential problem (i.e. it won't go into OD when it can't hold it). I use it any time I'm more than a few thousand lbs or so over unloaded weight. No need to disable OD that I've ever seen.
Yep, also locks up the converter in 2-5, and keeps it locked up so it engine brakes like a gas motor. Keeps heat WAY down. Forgot about that important point. Keep it in TH for sure, if for no reason other than the engine braking. The heat reduction is a huge bonus. Marc
I found out about the OD lockout about a year later as well!, damn Allison video doesn't mention this at all! :doah:. I use the tow/haul mode whenever I'm towing, in my honest opinion you don't need the OD lockout unless you're towing something big.
