2000 Bonneville SSEI - 198K on the clock...
A couple of weeks ago started car up after fueling. Got on the highway and it would no longer
go into 4th gear. I can feel the TCC lockup in 3rd gear, but at 55~60 mph and above it will
no longer drop into 4th. Code of P0128 was set - coolant was low. Topped it off still no 4th.
Things I have done: Checked TPS voltage - .5V at idle smoothly goes up to 4.11V at WOT. I
have shifted from D to 3 at speed RPM remains constant and no change between D and 3 at 65 MPH
Trans fluid is at the correct level and looks clear

The transmission occasionally hard shifts in warmer weather, but has not done so for quite some
time. Car drives well around town. After driving 20+minutes at 65-70 MPH at higher RPM
than usual it feels like it starts to miss. Drives fine around town, but I can't really take it on
the highway very far. No strange sounds from transmission it just simply stopped going into 4th.

Any Thoughts?

It's likely you are going to need transmissions service. Could be 4th clutch hub, or output shaft. A rebuild appears to be in your future.

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*Gone, but not forgotten* - Black 2000 SSEi, HIR Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, 180 degree thermostat, HS 1.9 rockers, LSx yellow springs, Intense FWI, PCM, shift kit, push rods, and 3.4 Pulley. ZZP Power Log.

This may be a long shot but since you mentioned low coolant does your engine reach proper operating temperature? The transmission will not shift into 4th (O/D) until this is reached. I guess a fluid and filter change would not be a bad idea if it was not done so in recent memory. Other than that I agree with Archon's advice.

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2004 Bonneville SE 151,xxx- 20% tint all around, 5% tint bar on windshield | 4500k DDM HID low | De-badged | Hardwired Passport 9500ix | FWI(inter-cooler piping) | FE2 Rear Sway Bar | Solid Motor Mount | 180* Stat | Firm Shift Kit



- '92 Bonneville SE - '85 Grand Am - '73 Catalina - '67 Catalina
- '87 Bonneville SE - '82 6000 - '78 Catalina [/color]

He's hitting operating temp And closed loop because he has TCC apply.

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2000 SSEi Galaxy Silver with New TEP Trans, A 62,000 mile engine out of grandma's car, all new front and rear suspension KYB/ Energy Suspension.
[url][URL=http://s871.photobucket.com/user/flatlander745/media/image-5.jpg.html][IMG]http://i871.photobucket.com/albums/ab278/flatlander745/image-5.jpg[/IMG][/URL][/url]

Sounds like the standard loss of overdrive: 2000-2005-other-than-gxp/topic25362.html

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Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

Thanks everyone!
harofreak00 - I checked out your pics on the side cover removal without dropping the trans
I may attempt it, but it will be really pushing my skill levels... Where can I find a manual for
the trans? without it, I would be lost. It is tempting if that is all it may be... I have time to
do some research as my shop has no heat and it is currently 20 degrees. Should warm up
soon though. I'll continue to read through your previous post - your symptoms and diagnosis
appear spot on, especially considering the mileage on this transmission

Thanks!

PM me your email address and I'll send you the manual.

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler