Tow haul and overdrive
Does tow haul lock out overdrive? Mine doesn't seem to or, I haven't observed correctly.
Forum Discussion
SoundGuy wrote:gmc6000 wrote:
No, tow/haul does not lock out overdrive on any GM or Ram truck, at least. Tow/haul only changes your shift points on the transmission.
I guess it depends on what one means by "overdrive" but I recently bought a 6-spd 2012 Silverado 1500 to replace our 2005 4-spd Avalanche for towing and in Drive when I engage Tow/Haul it absolutely does lock out 6th gear. If I disengage Tow/Haul while towing at highway speed and happen across a relatively flat section of road only then will the transmission upshift to 6th, otherwise with Tow/Haul engaged the highest it will go is 5th, which as it turns out is right where it needs to be - 2000 rpm in 5th, downshifting occasionally to 4th as road conditions may require.
You may want to try this unloaded: Get the vehicle over 100 kph and then engage tow/haul. If it does not downshift, your top gear is not locked out. If it does not go into top gear while towing, your vehicle may not be developing sufficient power at that speed to sustain 6th gear.
