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Ferg1 · 06-19-2022, 07:46 AM

What is the basics for this switch? Towing? Normal driving? Hills/wind?
It has 3 positions. All the way Out. And then 2 in
2007 tiffin allegro 32ba
W22 workhorse 8.l liter

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Alan_Hepburn · 06-19-2022, 09:21 AM

If it's like our 2007 Workhorse then the switch positions are:

1. Overdrive on
2. 6th gear locked out
3. 5th gear locked out

1JetDoc · 06-19-2022, 09:38 AM

Overdrive is an additional gearbox that allows your engine to run at lower RPMs (and consume less fuel) when running at highway speeds on relatively level highways. You would typically lock the OD out when hauling or towing heavy loads, climbing long grades or fighting strong headwinds.
If your rig has a tachometer (RPM gauge), keep an eye on the tach and use your OD Off switch to shift gears to maintain your engine's most efficient RPM range.

CamJam1 · 06-19-2022, 11:03 AM

I also sometimes use it when descending grades to get a little engine braking.

Alan_Hepburn · 06-19-2022, 11:24 AM

Quote:

Originally Posted by 1JetDoc

Overdrive is an additional gearbox that allows your engine to run at lower RPMs (and consume less fuel) when running at highway speeds on relatively level highways.

In the Allison 6-speed transmission it's built into the transmission: 4th gear is 1:1, 5th and 6th gears are overdrive gears.

Quote:

Originally Posted by CamJam1

I also sometimes use it when descending grades to get a little engine braking.

Again, with the Allison transmissions (at least 2007 and newer) you can just activate the Grade Brake and the transmission takes care of the shifting when you apply the service brakes.

Ferg1 · 06-19-2022, 11:58 AM

So if the little light is illuminated on the switch then overdrive is off otherwise its in 5th or 6th gear? Normal driving keep overdrive on. Towing/hills/wind take overdrive off?

Ferg1 · 06-19-2022, 12:03 PM

Or is it if switch is illuminated then overdrive is on?

1JetDoc · 06-19-2022, 11:03 PM

Quote:

Originally Posted by Ferg1

Or is it if switch is illuminated then overdrive is on?

Again... Watch your tachometer (RPM gauge). When running at steady highway speeds on a level road, your engine RPMs will be lower with the overdrive ON. If you turn it OFF, your engine RPMs will be higher.

Ferg1 · 06-21-2022, 04:11 AM

So when the button is pressed all the way in at the bottom it lights up and it says 6th gear on the instrument cluster. The tach at about 60mph is a little over 2000. If i push button in once at top/middle position light goes out on button and instrument cluster says 5th gear. Tach goes up also. if button is all the way in on top side light is off on button instrument cluster says 4th gear and o/d off lights up on instrument cluster. Tach also goes up. It doesn't seem like the button light should be on when in 6th gear.

edgray · 06-21-2022, 06:41 AM

[QUOTE=Ferg1;…………It doesn't seem like the button light should be on when in 6th gear.[/QUOTE]

I think you are correct. I believe WCC intended the light to be on whenever the switch is set to turn off either 5th or 6th gears.
I’m guessing Tiffin has the wires mis-connected and you should be able to correct it so that the light isn’t on when 6th gear is allowed.