You have to check for fault code in all modules.

The definition of overdrive is when the output turns more than 1 revolution for every revolution of input. Mercedes do indeed have overdrive - 5th gear in my car is (92 300SE) is 1 revolution of the transmission output shaft to every (I think) .70 revolutions of the crankshaft.

Overdrive can be in any gear (the latest Corvette has OD in 5th and 6th gear).

Far as I know, any MB car that has a 5 or 6-spd automatic has OD in the top-most gear.

The shifter bushings can make a big difference, especially if the shifter is vague enough (due to the missing bushings) to not properly set the shift-position switch to tell the transmission that top-gear has been selected via the shifter. Try downshifting to 4th and then upshifting to 5th and see if that helps.

I'd get the bushings replaced - and pulling codes is definitely good advice.

Thanks for the the tips. The check engine light does come on once in a while, but goes out after a day or two. I'll check the codes. I'll see about the bushings too.

The trans control maodule can set off the check engine light, definte good advice to check the faults in both modules.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

Thanks for clearing that up. I was refering to OD in the American and to a certain extend Japanese car sense. Ie it operates as a 3spd and won't shift into "OD" unless you push a butten or move the gear lever. But you can't use it around town because it lugs the engine down, or in Toyota's case overheats the trans. MB's use a straight 5spd, 4spd whatever, put it in drive and it does its thing.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Hatterasguy - OK - gotcha.

I'd always heard about that issue with American cars, too, but I've largely ignored it on the cars that I've had with no negative effect. The biggest problem I've seen, and you noted it in your reply, was the lugging effect from being in too high a gear at too low a speed.

My '92 300SE doesn't shift to 5th until 50mph, which prevents that lugging problem, but I'm having a time getting used to that high shift point vs my '93 Lincoln Mark VIII which shifts to 4th (OD) at about 38.

Transmission design dictates the implementation method of the OD. In my Lincoln, it's the same as my MB, the OD is electrically controlled. In my previous Lincoln ('92 Mark VII), OD was mechanically selected via the shifter - but the wierd car lacked a shifter position for 2nd - only had 1, 3 & 4 as valid shifter positions.

I think in the case of the 722.5 transmission, it's basically a 722.X 4-spd tranny with an electrically-controlled OD gearset added post-design.

Who knows - just so long as it works - with a 3.69 rear gear, I need OD bad....

See they changed that on the later cars. If you had a 722.6 it would shift right to 5th. But they kick down so quickly lugging is not an issue.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Yeah, and if I had a 722.6 transmission, I'd be stuck with that liquid-gold fluid available only from MB and by special dispensation from the Pope.

I think I'll take my old, dated 722.5.

I can also check the transmission fluid level on the tranny without some special Scotty-From-Star-Trek gizmo.....

Ain't technology grand????

I like the 722.6 a lot actualy. You almost never have to change the fluid or check it. And it actualy down shifts without having to beat it, like the old 722.4.

To each his own I guess. Local dealer charges $200 for a fluid change, bring it in every 60k-80k miles, other then that forget about it.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

It's always sooo boring to hear from guys that don't have the new stuff--and therefore have no clue--just how bad the new stuff is.

A Mercedes with a 5- or 7-speed is light years better than the old 4-speeds, especially those that start in 2nd--meaning they're effectively a 3-speed. The new transmissions really transform the car's performance.

A few bucks more for fluids is irrelevant in the big picture.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles