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1996 Deville 1985 Fleetwood
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74 Posts
Discussion Starter · #1 ·
Well i noticed my deville has been starting in 1st gear and skipping 2nd gear and shifts striaght into 3rd. If I step on the gas hard to make it down shift it over revs the engine like it was in nuetral, then it finally grabs 3rd again if i leave off the gas pedal. So i have no 2nd gear and no 4th gear I took a fuse out for the transmission and it defaulted it to 1st gear. I think I need a new tranny any thoughts?:helpless:
 

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1996 Deville 1985 Fleetwood
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74 Posts
Discussion Starter · #2 ·
also if i do need to replace it can i use a older transmission from a 99 deville can I just take out the valve body out of the 2000 deville and put it in the 99 transmission so the connections would hook right up?
 

· 2000 Deville
1996 STS
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338 Posts
Hello Delatorre.. I was experiencing shiftting problems similar to yours.. A cadillac mechanic i know told me to change the Vehicle Speed Sensor also know as the VSS.. I changed the sensor and have'nt experienced those problems in months.. Its a cheap part.. only like $30 or so.. Its worth a shot.. Also my check engine light was not on.. No code at all for the VSS came up in the current or history codes.. So there dont have to be codes for it.. I just took a gamble and it worked out.. Good luck..
 

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2006 XJ, 2000 Eldorado ESC--total loss :(
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1,180 Posts

· Registered
1996 Deville 1985 Fleetwood
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74 Posts
Discussion Starter · #5 ·
no check engine light no codes that point to a shift solenoid, I did change one of the shift solenoids because i had one laying around from a 99 deville but the other solenoid had a different connector I even changed the fluid the pan had a thick gray sludge on on it i changed the filters also becuase they had little flakes in it. when i took the shift solenoid out i applied 12 volt to them and they clicked. thanks for the suggestions just dont want to throw in another transmission if its not needed. I'll also try changing he vss sensor i think i have one laying around somewhere.
 

· Registered
1996 Deville 1985 Fleetwood
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74 Posts
Discussion Starter · #6 ·
Well these are my codes
C1224 HISTORY
C1248 HISTORY
B1327 HISTORY
U1000 CURRENT
B2767 HISTORY
P1540 HISTORY
C0660 CURRENT
U1040 HISTORY
B0268 HISTORY
B0429 HISTORY
P0151 HISTORY
P0174 HISTORY
P0420 CURRENT
P0532 HISTORY
P0533 HISTORY
P1845 HISTORY ( This one maybe be causing the problem)
 

· Registered
2006 XJ, 2000 Eldorado ESC--total loss :(
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1,180 Posts
P1845 - 2-3 Shift Solenoid Circuit Low Voltage

I don't know with it being a history code, but your problem of missing 2nd and 4th does not sound anything like a VSS problem. Does your speedometer still indicate correctly? It sounds like the textbook definition of the shift solenoid failure. I don't know about the solenoid interchange between years, but I'd just get 2 of the updated ones from GM and replace them both. I can't find the info at the moment, but I know those 2 solenoids control all gears. The different on/off combination of solenoids A and B give you 4 forward gears.
 

· Registered
1996 Deville 1985 Fleetwood
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74 Posts
Discussion Starter · #8 ·
ok ill call the dealer up and pick them up, rather spend 100 bucks just to make sure before i swap the drivetrain out and spend 700 for a used tranny. The speedo works fine doesnt jump or stop working. When im cruising on the freeway and i let off the gas pedal the car's rpm will drop to about 900 it likes it falls out of gear maybe trying to shift to 4th gear but as soon as i press the gas it bumps into 3rd
 

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2006 XJ, 2000 Eldorado ESC--total loss :(
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1,180 Posts
I hope that's all it is, sure sounds like the shift solenoids. Not sure about the rpm drop--900 rpm is awfully low (more like the trans is going into neutral... ). Could simply be because the trans is not locking the TCC, it won't do that in 3rd gear, and probably also won't when there are other issues with the transmission.
 

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2001 Deville
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10 Posts
Hey guys newbie here.

I'm looking ay buying a 2001 Deville from my buddy with transmission problems. I did a lot of searching and found this thread. The transmission in this car drives around town fine but when on the interstate it won't downshift when climbing hills. I drove it once around town but didn't pay attention to which gears were working and which weren't.
My buddy said that the dealer told him it displayed a code for a certain solenoid in the transmission but he couldn't remember which solenoid. I can go drive it again next week and also pull the codes but I was wondering how I might determine if it is a shift solenoid or one of the others? I know sometimes codes will store for one problem but that isn't necessarily the actual issue.....it might be something else causing that to malfunction.
He wants $800 for the car and I plan to do the work myself. If I can put under $100 in parts to the transmission I'll come out pretty good. The rest of the car is in pretty good shape. It has 202k miles though......
I'm hoping I can get away without having to buy a used transmission for $500+

What are your thoughts?

nate
 

· Administrator
2002 F55 STS, 2014 Explorer XLT, F-150
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80,389 Posts
The 2001 drivetrain uses a GM 4T80E transmission - if the car is a Base or DHS it uses an economy final drive of 3.11:1 and that's the transmission that must be duplicated. The unit uses a pair of 1-2 and 2-3 shift solenoids with line pressure control engaging 4th (overdrive at 0.681) gear. The solenoid of which you speak - highway loads - is the TCC system - Tprque Converter Clutch. At road load speeds above about 43 mph the TCC engages a viscous clutch in the torque converter to remove most of the last 300 or so rpm of slip between the stator and rotor.

To test the TCC, moderately accelerate through the 4 gears, to about 50 mph....... as you ease off the gas to maintain cruise speed you should hear/feel/see the rpm drop slightly. OK ?? If so, maintain speed with your right foot and touch the brake pedal with your left foot - the brake switch affects TCC and Cruise Control engagement....... as you touch the brake pedal you should hear/feel/see the rpm rise a few hundred rpm. OK ?? release the brake pedal and TCC should engage again. it should take only moderate GAS pedal pressure, for acceleration or passing, to also drop out TCC during the period of power demand.

The car has its own built-in diagnostic code scanner/memory. Study the proper year/model group in the "How to pull codes" sticky just above. P 1860 (either Current or History) is the TCC operating solenoid. IF the car is not subject to emissions you can live with the extra 300 rpm and loss of about 1.5 mpg highway....... but the TCC is an emissions system and the car must pass federal emissions to be sold legally.

To reiterate: You should feel 3 very distinct gear changes during acceleration with a gentle rpm decrease above 43 mph as you ease off to cruise gas pedal.

Heres's a table of car speeds vs. rpm with TCC engaged. (Remember - the base Devilles are speed limited to 112 mph, so disregard the 3.11 graph above that speed)
 

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2001 Deville
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10 Posts
Well I bought the car for 700 today and drove about 40 miles home. Some Interstate and some not. It seems to drive fine to me.....
What I did notice is that around 75mph and climbing a hill it does downshift but it kinda "surges" a little. The tach goes no higher than 3200 RPM and it acts like there is not much power. It acts like a governor does except instead of limiting mph it limits rpm.
 

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2001 Deville
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10 Posts
It is around 2k when cruising at 75. I can see and feel it drop. It's the downshift and surging that I experience. It doesn't want to go any higher than 3200 rpm at those hwy speeds. It will go to 4600 rpm in the lower gears though.
 

· Registered
2001 Deville
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10 Posts
Update:

My good fortune is definitely over with this car. driving home on Friday it went well until I got off the interstate and onto the secondary highway where I immediately climb a big hill. The car acted like like it didn't want to shift down and started hurking and jerking and went into limp mode. About this time the engine started to overheat a little too. The RPM's were all over the board during this whole time. I also had my 2nd flat of the day at this same time......
Anyway, I got a ride back to town to fix the tire and when I came back things had cooled down a little and I was able to accelerate to about 64 mph before it went back into limp mode. This morning I attempted to drive it back to town after clearing the codes and letting it sit all weekend and I wasn't able to go a mile before it started all over again. Following is a list of codes that I pulled on Thursday and then cleared, and then another list I pulled this morning and cleared. Does this sound like a failed TCC solenoid or does it sound like transmission replacement time? I'm fine with either but I need to get started ASAP as I'm losing my shop access in a few weeks. TIA

Thursday codes:
P0140
P0141
P0741
P1415
P1567
P1860

codes set on Friday:
P0742 - TCC circuit stuck on
P0733 - INCORRECT GEAR 3 RATIO
P0732 - INCORRECT GEAR 2 RATIO
P0404 - EGR FEEDBACK SIGNAL OUT OF RANGE
P0137 - O2 SIGNAL LOW
P0036 - HO2S HEATER CONTROL CIRCUIT B152
 
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