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Hard Downshifts

10K views 19 replies 12 participants last post by  kd5hlw 
#1 ·
I haven't been on in a while and just putting the Redline away for the winter but wanted to post this to see if anyone has experienced this. In September my wife and I drove from Maine to Niagara Falls, took the week and 4 nights away. A little over 600 miles over and no problems with one night on the way over. The car sat the first day in the parking lot 90 degree heat. We decided to go to a wine tasting so I reached in and just started the car (usually I turn the key to run for a few seconds before starting) to get the AC going. I noticed on the DIC it said check traction control. We took the top down and headed out, we almost got thrown through the windshield on the first downshift and noticed a short but not hard up shift. Drove about 15 miles with very hard down shifts the whole way and went to the wine tasting. When we came out I turned the key to run for a few seconds then started the car. It has been perfect since. 600+ miles home and a few short drives and it shifts and goes perfect. I am very happy about that but curious if anyone has had this happen.

Thanks, Steve
 
#2 ·
I'm not an expert on the vocabulary for what you are experiencing, but I'll bet if you search for HARD DOWN SHIFTING, you will read about that issue and what needs to be done. The good news is it can be corrected for less than a hundred dollars and you can change the items with a screw driver. Good luck.
 
#3 ·
I have read everything on the constant hard down shifts. As I said this happened only once and the DIC indicated check the Traction Control. After the next restart it has been perfect. Maybe just a computer thing or something just happy it's shifting correctly now.
 
#6 · (Edited)
Do you have a CEL? I would change both the intake and exhaust camshaft solenoids. Their very inexpensive (about $40/each) and about 5 minutes to replace. Do some research on the hard downshifts and you'll find that a lot of people have replaced these and it will fix it. My guess is that one of them is starting to go and it's causing this issue. How often do you change your oil? My other word of advice is to check your brake fluid level (will cause your traction control light to come on!!). If it's a bit low, it's either leaking, or it's time to replace your brakes. While I don't have the post count here, I'm a regular on the Solstice forum....
 
#8 ·
This is the first I have heard about the traction control light being related to the camshaft solenoids, or about hard downshifts being a temporary condition.
 
#9 ·
In the transmission succage thread we learned several things.

First is that the failure of the cam servo will cause the TCM to go into protection mode and you get hard downshifts.

Second was that the cam servo can and do "fail" intermittently. In fact, it took nearly a year of collecting clues to figure out that the servo did cause this hard down shift condition. The usual scenario is the driver experiences a random hard down shift followed by "normal" operation. Then another hard downshift. So they take it to the dealer and say "fix this". The dealer finds no codes and in test drives can not reproduce the fault so give the car back to the owner who drives the car for a week or a month and gets another hard downshift. It became clear over time that the cam servo can experience an intermittent failure to operate within the required parameters and the hard shift condition occurs, then the "problem" clears itself and the hard shift condition goes away.

Some have observed contamination on the screen on the oil input at the servo and assumed that the contamination was affecting the operation of the servo. Others have suggested that the servo can fail intermittently mechanically and then return to normal operation. Randomly.

Over the past few years, the vast majority of cases of hard downshifts reported have been solved by replacing the cam drive servos. My personal experience with multiple RMSSC cars that have seen hard downshifts is that in every case, replacing the cam servos solved the problem.

I have not personally learned of a TCM failure but recognize that it is a possibility. But as I said above, we have seen many instances of servo failure.
 
#10 ·
We have begun to see TC and ABS failure warnings over the course of the past couple of years. They have all been a single occurrence that were reset by cycling the ignition. In at least one instance, we had multiple warnings on a cruise as we went over a mountain pass. My belief is that they are false warnings due to a condition related to the sensors resulting from aging of components. There have been no actual failures and in every instance normal operation was returned upon a restart.
 
#15 ·
if it is shifting randomly at highway speeds that is not the same failure mode addressed in the succage thread. That was hard downshifts on deceleration randomly.

You may have a "hard" failure in the TCM or BCM that can be diagnosed by a dealer. Find one who will look at the car without charging an arm and a leg and see what they say.
 
#16 ·
Some minor downshifting in mine recently. Colder weather has had this effect before in mine. I expect it to happen now. First time it did it, shocked me. I read the threads, know about the fixes, so far its normal for me and my car. Not super bad, nothing throwing me or the car around, runs like that until it does warm up. Cold is cold for some of us. AND it is cold here.

IF mine gets worse more pronounced in anyway, then I will change out the intake/ext. cam sensors. I too have not heard or read about the TCM or other things resulting in hard down shift. Does not do it on mine, so far. My car takes a bit of time to warm up, then she is all go. Tire temps, brake pads, transmission, coolant, power steering... you in the cabin, until the heat gets working right, IF you are in colder weather sections of the country. Even if your not in the cold, go easy first few miles before you cut loose. I do, that's just me. In cold weather driving, everything takes time to heat up, even you. No racing at Summit Point this past holiday. Turkey Bowl canceled because of icy conditions. I knew that...

I let my car warm up until it's not warmed up. The hard shift down to 1st or 2nd is very minor for me now. I know about it, have experienced it before in winter, or on hill decent. Still the same since I bought it. No worse no better. Right now I can deal with it as it. You may not have that same thought with your car. Object are closer in the mirror than they appear... ever car is a little different than it's sister or brother out there. This one does hard shifts, this one not so much, this one not at all. This car has been fixed, still downshifts hard. This one has been fixed, no hard shifting ever again.

You can fix it, the dealer can fix it, IF it needs fixing here? Truck transmission in our cars. Bargin basement parts bins for us, cheap... not every thing has MB quality to it, know what I mean.. it is a Saturn after all. IF the TCM or BCM needs to be checked over by the dealer, ok then, they too like us owners know this IS a problem with our cars. There is history here.. with this issue of hard downshifts with the Kappa.

LAC
 
#17 ·
I seldom drive my RL in cold weather, but today there was a need, about 15F. Car shifted hard, both downshifts and upshifts. I'm glad it wasn't slick, or it would have been hard to control. After 5 hours parked outside at night, I drove home, and the transmission shifted normally, even though the temp. was lower. We will watch and see what develops.
 
#18 ·
Here is an update on mine this winter. Been cold here, I have driven in this type of weather many times. The upshift from 1st to 2nd is minor when first starting out. Not hard in any sense. 2nd to 3rd.. even less so.

Under 32 degrees, under 25 miles per hour, with the HPFP not under any load, with a semi cold transmission it might do it. After all shifts in the first 3 miles of use, when the HPFP is under more load, nothing. Works fine. Yes the intake/exhaust cam solenoid should be changed out IF... you are having a head snapping experience downshift.

During warm weather... first upshift minor again with a rough feel to it. Then all shifts are normal. As for downshifting hard, this only happens to my car... yours and other will vary here, when under a steep downhill grade, with slowing and no load on the HPFP, IT might downshift hard from 2nd to 1st only. Once on flat surface, the shifting is normal. I think.. imo, outside of the cam servo replacement option, cold trans fluid or an uneven balance in the trans fluid levels, without load from the HPFP, the ECM could go in to protection mode to save the trans, assisting the braking? Maybe?

Been ok this winter.. cold start, warm up trans fluid, first upshift hard, then less as the trans fluid heats up to temps. IF mine had been worse this winter, due to their age, I would have replaced both parts by now. Weather is warming here... come on 65 degree's I'm ready....

Your car will be and act differently than mine does. Hard upshifting/downshifting check the replacement options for these parts asap.

LAC
 
#19 ·
Updating original comment. I have had the car out 4 or 5 times so far this spring no long trips but about 450 total miles. The car has not repeated the hard downshift and no traction control warnings on the DIC. I have as I usually do turn the key to the run position for 8 or 10 seconds and let the DIC light up and do it's thing before the first start, hoping the electronics get to where they need to be before starting. So far so good runs and shifts great.
 
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