2003 Tahoe Z71 with 5.3 ... when driving in any gear except 4th, the Ho will shift out of lockout when the towing button is pressed - it is audible and RPMs increase like they are supposed to - increase of about 400 or so.

When the Ho is in 4th, however, the towing button does not seem to make any difference ... shouldn't it cause the trans to shift out of lock up?

I have been trying to determine why I can't do any better than about 14 MPG on the highway at 60 MPH - turns about 2000 RPM at about 62 mph.

Any ideas?

Thanks!!

As for the rpms, what is your gear ratio?

Sorry about slow reply!

Just checked codes in glovebox - it shows "GT5" which is reportedly a 4.10 ... ouch, certainly doesn't help ...

Thanks!

George

Wow! With 4.10 gears, who needs a tow/haul button. My 02 does the same thing as you are describing but with 3.23 gears. I cannot get the trans out of lockout while the button is depressed. As soon as I release the tow mode it goes into 4th. Now, when I am already in 4th and depress the button, it stays in 4th until I slow down and then it stays in lockout indefinitely. Dunno what to tell you but I sympathize.