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Pontiac Bonneville Transmisssion

Yeah i just bought a 1999 bonnevile SLE when i first got it the transmission was basicly ruind. My fourth gear was pretty much destroyed. So the dealership replaced it and now its shifting hard and hesitating when shifting into 2nd and 3rd, and bogs down when im going around 30 MPH. People keep telling me to let in get broken in cause its knew but i dont know.


  • Hey, you probably had this fixed by now, but I had a 99 Bonneville that needed a transmission at 108,000 miles. It broke my heart to spring for it, but that was the only repair that car EVER needed that wasn't maintenance. I would find a transmission mechanic that is certified (ATM or ATD, can't recall what they're called) and get another opinion. You shouldn't have to break it in. Mine was guaranteed for 10k or 1 year. Unfortunately, my 7 years was up on my GM card so I traded it. Big mistake. 06 Impala is a huge disappointment. (6 times in garage in 4 months). I'm looking for a B-ville on ebay now. Does anyone out there know the reliability of 04 and 05 Bonnevilles? I was warned not to buy any 00-03 models. Thankx.
  • No its still acting up, and my fuel line as bursted twice. Its in the shop right now, and i got some seafoam for my tranny, so ill see what happens.Also ive heard that on the 00-03 bonnevilles have problems with the gauge cluster with the lights going out, and the cd player sometimes goes into lock mode for no reason.
  • my girlfriend has a 95 bonneville with a bad tranny and i found a tranny thats in a 93 bonneville for a pretty good price at a local junkyard that comes with a 30 day warranty. I know or at least ive been told that the tranny itself is the same, wut i need to know is if the plugs for the wire harness is the same. so basically wut i need 2 know is will the tranny out of the 93 work and is compatible with the 95. if anyone could help answer this question for me i would greatly appreciate it. thanks
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    Send me an email at the address you read in my profile. Click on my name at top of this post. I can possibly direct you to people who will know. I assume you know the transmission is definitely bad; some engine problems can make somebody think it's transmission problems.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • Ya the wireing harness will work with the 95 bonneville, the 95 and the 93 transmissions are exactly the same.
  • benny17benny17 Posts: 5
    I have a 99 bonneville sle and i was wondering if i could change the tranny with a 99 ssei transmission, or would this cause problems?
  • car runs good but sometimes it seems like it gets stuck between overdrive and third and sometimes about 65-70 it will kind of loose power and vibrate, you let off the gas or push it down further it quits for a while mostly on inclines
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    How many miles on the car?
    When were the spark plugs changed last?
    When were the spark plugs wires changed last time?

    My suspicion is that it's the plug wires or the plugs. It probably is lugging at a low RPM in 4th on a slight incline and you accelerate slightly and it's misfiring. Try driving the same circumstance or place with the car in 3 instead of 4. That will keep the motor turning faster and you won't notice the slight misfire.

    Or you can do the incline at a lower speed in 3rd at th same RPM and it probably won't do it because in third the load on the motor won't be as great on the same incline because of the lower gearing.

    It might be a transmission probably but I doubt it.

    You can go to one of the auto parts stores that does free scans for codes on your car and you'll probably have a code for misfiring and it may give a particular cylinder on which it occurs or it may be random misfire. Advance Auto does it in this area. Even though the check engine light is not on there may be a code. If it gets worse the code might cause the light to turn on.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • Hello all, when I accelerate quickly from a dead stop my transmission, or at least my front wheels chatter or maybe a better description would be the feeling of ratcheting. this ratcheting can be scribed as on the verge of violent, once again this only occurs from a dead stop. No other anomalies are noted at any other speeds or shift points.
    The year is 1999 with around 140,000 miles.
  • I have a 96 Bonneville SSEI that sometimes while driving it feels like it is stuck in 2nd gear. If I turn the car off and then back on it sometimes shifts fine then, first thru overdrive. Could that be transmission modulator valve or transmission control solenoid? Tranny was flushed and new filtered in December. Also, were is transmission control solenoid located.
    One day it shifts fine and the next day it may not.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    >Tranny was flushed and new filtered in December.

    Do you mean it had one of those flushes where they connect hoses and supposedly change all the fluid without dropping the oil pan and replacing the filter?
    If so, did they put in an additive?

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    >wheels chatter or maybe a better description would be the feeling of ratcheting. this ratcheting can be scribed as on the verge of violent

    Does it seem like the firewall under the windshield is jumping up and down? That may mean that a certain part, I believe a Sprague (spelling?) is slipping. Try using 1st gear and see if the same thing happens. I'd recommend against accelerating hard enough to cause that to happen. It may be reduced pressures in the transmission due to wear on the pump. It may be pressure control valve; some of those have had problems. Your transmission has 140K miles and that's good.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • My 95 Bonneville will run down the hiway for about 15 minutes in overdrive, and will, on its own,shift back into drive, and will not return into overdrive unless I stop for fuel or to let it cool. When I resume the trip it will work fine for about 15 mins. and then do the same thing again, every time. Can anyone help me determine the cause of this problem? Thank you.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    Is your motor overheating? I believe it turns off the lockup torque converter and may shift down into 3rd if that occurs. That spins the motor faster, circulating water faster, and cools down.

    Are you running too cool. Without checking a 93 manual and 98 that I have, I believe it won't shift into 4th under the coolant reaches a certain temperature on a cold startup. The obvious reason is pollution control and running faster which heats up the coolant faster decreasing pollution. IF your thermostat is opening too much the motor may be cooling too low and the PCM is doing what it is supposed to do.

    I suggest these fairly innocuous reasons it may be doing things strangely, because you haven't said anything about shift quality being back. Late, early, rough upshifts. Strange shifting while cold or coming to a stop aren't mentioned.

    If your car has a temperature gauge, follow it to see if things are acting normally. If the thermostat hasn't been changed in a few years, that would be my first suspect.

    Are you in a cold climate?

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    Is your transmission fluid low? That was mentioned in the service manual for the 4T65E transmission. I believe you have the 4T60E. I'll check that manual later when I find it.

    Another factor might be the temperature of the fluid is going high and the transmission downshifts out of overdrive.

    Are the other three speeds all working completely normally? Can you feel the transmission go into 4th and then the lockup torque converter latch in which reduces engine rpms more?--when the trans operates normally.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • The problem started a few years back while pulling a small trailer, and only happened while pulling the trailer. But of course has worsened to where it happens without the trailer.The rad. was removed and boiled out, and the fins cleaned. The Therm. has been replaced a couple of times. It shifts fine, and predictable. As far as I can determine this trans is not electronically controlled. However, it apparently has two sol. valves, one for the 1-2 shift, and one for the 3-4 shift. Plus another for the lockup. On the older and smaller 125 series trans, the lockup sol. gave trouble holding the converter in a locked position, and not locking up at all, and needed to be replaced. Could this be the problem here? I can't tell if the trans. is running too warm. If it is, it is not bringing up the coolant temp. The coolant temp runs a consistent 190-195.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    The small trailer probably should have been towed in 3 where the higher ratio would have allowed an easier tow and the fluid would have stayed cooler.

    Or an external cooler can be put in the trans fluid line after the fluid goes though the radiator and keeps the fluid cooler.

    The neighbor had towed a boat with his Blazer in 4th gear without a cooler once a year to the Lakes area in Southern Kentucky--mostly interstate, and hurt his transmission with overheating.

    I believe you have a 4T60E which means electronic controls. But diagnosis is needed.
    Has it had a filter change in the last 30-40 K miles? I hope it's something simple like a solenoid for the torque convert lockup.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • Yes, the firewall does seem to jump. I will try using 1st. gear this morning to see if it makes a difference and I have been trying to baby the acceleration. Thanks
  • Yes, you are right on using the lower gear to pull a trailer of any size! I'll have to check the records for the oil and filter change. It is a 4T60E, but is there a separate module that manages the transmission, of is it managed through the ECM? You mentioned diagnosis, is it possible to pull a code tor this kind of problem? Thank you for the help.
  • My 95 Bonneville goes into overdrive once then when you pass someone it kicks out. The car has to be turned off and restarted for it to go back into overdrive. The other gears are fine. It has been in the shop 3 times for this problem and it still is not fixed.
  • rhtransrhtrans Posts: 84
    Take it to a different shop!
  • kaylee01kaylee01 Posts: 2
    The 95 Bonneville has been to several shops noone can find the problem with the overdrive. The cylinoid has been changed and so has the transmission wiring harness and it still only goes into overdrive once. When you speed up it kicks out and won't go back into overdrive until the car is turned off. So I was hoping to see if anyone else had experienced this problem and what the outcome was.
  • victor53victor53 Posts: 7
    Yes, when I manually place the transmission into first gear the transmission feels solid, smooth and accelerates without hesitation.
  • i own a 95 bonneville sse it is now mar 08 i have 400k on this car i have done a lot of matience and repairs over time but now im having a problem with my transmission. the car runs great no major problems as i fix stuff before it goes. my transmission died 2 yrs ago so i bought a used one at a junk yard, i had a friend install it for me he knows cars preety good and has always done good by me. when he put the trany in he told me he had problems with the linkage cable??? now my car has a hard time shifting out of 2 gear i have to almost redline it to get her into 3 and even 4th. i was wondering if anyone knows if the linkage cable could cause this or is it another problem. i do most of my own work on my cars but i have never messed around with a tranny be4 looking for some insight thank you for your time guys.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 23,602
    What year and model car did the transmission come out of?

    Where year and model is your car? I am curious if you got an identical transmission or it was a similar model. If you know the model the car came out of, you can call a recycling yard and ask if it's right for your car.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • my car is a 95 pontiac bonneville sse the replacement tranny came from same yr and model, she has started to have a hard time upshifting and i was wondering if it could be something easily fixed or should i just look for another tranny
  • arehmarehm Posts: 3
    I have an 01 SSei Bonneville with 80k on it it has recently started shifting hard after it get warm. I was told that it could be going into LOPE mode. I also read that chjanging the thermostat and adding a trans cooler should take care of the problem. Anyone else had this problem or know what it might be?
  • I had the same problem with my 94 Bonneville SE (currently with 279,000 miles) about a year ago. I didn't go on the highway much, but every time I did I'd have to shut the motor off for a few minutes to reset the computer after the car shifted into the passing gear. It didn't do it that much so I just dealt with the problem, but now it will not go into overdrive at all. I went from 400 to 475 miles on an 18gal fuel tank (approx. 26.4MPG), down to 225 to 275 miles (15MPG) just because this car runs in the passing gear all the time. At 72-73MPH it runs at 3200-3300RPM. It should be at about 2100RPM in overdrive. With gas prices as high as they are, I will save myself more money than I will know what to do with... lol I have been talking to a few people and every one of them told me it sounds like the "transmission Control Solenoid". There are two of them, (the TTC lock-up and shift solenoid 1st-2nd and 3rd-4th & just a regular Solenoid) in my vehicle, and thankfully they are both external meaning they are on the outside of the transmission, and not inside that trans. pan. The Torque converter clutch lock-up (TCC Solenoid) is the one that works the overdrive gear I think, but I am not 100% sure. I am going to be changing both of these just to be safe. AutoZone has them listed at 28.99 and 26.99, one is in stock, and the other is a special order and will take 1-3 days to get. If you are still trying to get information about your problem, just let me know by e-mail, and I will let you know if by changing these two solenoids, it corrected the problem. My email is josephbelles (at) g mail (dot) com You can also see these parts by going to this website. (,11200623/shopping/partTypeResultSet.htm) Have a Great Day!
  • I have a 1994 Pontiac Bonneville. It roared like hell up to 120 mph before I took it to Big O Tires to have the pan gasket changed because it was leaking. Once I got the car back now it won't go over 60 mph. Any suggestions? Any and all advise would be greatly appreciated! :mad:
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