How can I tell if running in OD at hwy speeds?

Silverado4x4 · December 25, 2016

6-Speed Automatic Transmission

Gear before shifting from D

(Drive) to M (Manual Mode)

6th 5th 4th 3rd 2nd 1st

Range after shifting from D

(Drive) to M (Manual Mode)

M4 M4 M3 M2 M2 M1

So using the chart in the manual (above) if running in 6th, it will switch to 4th when M is selected.

+/- button can then be used to permit shift to M5 and then to M6.

EDIT: don't forget that the M mode cannt force an upshift. Selecting M5, for example, means the trans can use any gear up to 5th.

It will up-shift on its own in M1, if your in M1 and the rpm's max out it will upshift to M2 to protect motor from over rev.

Cowpie · December 25, 2016

Both the top gears on the 6L90 are OD. If you weren't running in OD at highway speeds, you would have that engine really screaming.

pl8man · December 25, 2016

redwngr · December 26, 2016

It will up-shift on its own in M1, if your in M1 and the rpm's max out it will upshift to M2 to protect motor from over rev.

You mean on throttle or on grade braking? (or both?)

If the chart is correct, the only way it ends up in M1 on an auto to manual shift is if it was in A1 when the shift was made.

Ravenkeeper · January 13, 2017

How can I tell if the truck is running in overdrive? The rpms on my 15 1500 5.3 4wd sit at 1800 or so rpm on level road traveling 75mph. Is this right? I never really payed attention before, but it seemed kind of high. I'm running 275/65/18 which is 2% taller than the stock 265.

Thanks

Under similar conditions on mine (20" tires, RWD), my truck switches from "V8" to "V4," on the flats and downhills.