Hard Shifting

lukebrown

I know this topic has been brought up before, but I'm at my wits end. I have a 2000 Buick LeSabre that I've owned for about 8 months. Right when I got it, it would shift hard every once in a while. 8 months later, it shifts hard all the time. The only time it doesn't is in the morning when I drive it for the first time. My drive to work is about 5 minutes. After that, it will shift hard all day, even if it's been hours since I drove it last. I read on multiple forums that these Buicks had a problem with the pressure control solenoid. I went home a couple weekends ago to my brothers shop and we tore the whole car apart getting to that solenoid. We replaced it and put everything back together. It worked perfectly for about a week, and then promptly started up again. Infuriating. Now, it's acting exactly the same as it had before. Any ideas? Why would it work for a week and then quit again? Fluid has been checked multiple times- same level all the time. I tried taking the battery cable off to reset the computer as one forum recommended- no help.

Mr_Shiftright

Did anyone scan the car for diagnostic codes? It's possible that the PCM is increasing line pressure to compensate for slippage. This will also give you rough shifts. Also were new fluid and new filter installed?

thecardoc3

Did you only replace the pressure control solenoid (dealer part?) or did you remove the valve body and clean it and inspect the valves and valve bores for wear, especially the torque signal regulator valve?

lukebrown

Sorry guys, took way to long to get back to you. I took your advice and took the first chance I had to go to Autozone and get the codes read. The code came up with P0742. It says that the Torque Converter Clutch is stuck on. A mechanic told me that the new torque converter clutch that I just used to replace it might have been faulty. Not happy with Wells for producing a crappy part, although I've heard their other parts are great. There may be some gunk in my transmission that got stuck in the old one and new, so I'm going to replace the filter and fluid. I'm very stupid for not replacing the filter the first time. Luckily, now that I've done it once, this time won't take nearly as long to replace the part. @thecardoc3, I only replaced the torque converter clutch. Whenever I searched for pressure control solenoid online or at local part stores, the only part that was recommended was this one: Link

I didn't do anything with the valves and valve bores. I also didn't do anything with the torque signal regulator valve. Frankly, I don't know what those things are. I'll ask my brother the pro when I'm home to fix it. Can you tell me a little more about those things?

Mr_Shiftright

I wonder if the Torque Converter Clutch is actually stuck on. Seems to me the car would stall when you come to a stop, but it doesn't do that right? The P)742 code can also indicate faulty wiring or a faulty TCM. Also, Autozone may not have a scanner sophisticated enough to read all the codes relating to the transmission.

imidazol97

The description in the first paragraph says this rough shift doesn't clear with just turning the
engine off for 30 seconds or more and restarting, like the typical PCM symptoms do.
The computer resets and requires 2 shift times that are too long before going into
high pressure mode to protect the shifts.

Diagnosis is needed. There's a 13 step diagnosis flow chart for the 03 and P0742 in the
FSM. Requires a scan tool and ability to read pressures.

Quoting the 4 GM Diagnostic aids:
The customer may notice an engine stalling condition.
If the scan tool indicated TCC release pressure was present in Step 2 (of the flow chart) and a mechanical or hydraulic condition was not found in Step 8, an intermittent short to ground condition may exist in the TCC release switch signal circuit. Refer to Intermittent Conditions on page 6-529 in Engine Controls.
Do not replace the torque converter for this condition, refer to Torque converter Replacement Guide on page 7-181 for other concerns.
Residue or contamination may cause valves to stick intermittently.

You didn't mention engine stalling.

I'd change the fluid and filter and hope that maybe it's valves and some residue causing them to
stick. Walmart has Supertech brand Dexron VI which is what I use.

Did you replace the torque converter clutch or the PCM?

Seek professional help. But was the code cleared?

Here are the 4 pages about P0742 for you to read through.


http://i86.photobucket.com/albums/k110/imidazol97/P0742P1_zpsju5ona78.jpg
http://i86.photobucket.com/albums/k110/imidazol97/P0742P2_zpskxarvndt.jpg
http://i86.photobucket.com/albums/k110/imidazol97/P0742P3_zps7p3djhg8.jpg
http://i86.photobucket.com/albums/k110/imidazol97/P0742P4_zps5tcddryk.jpg

neonbeast

hey i have an 05 neon sxt 5 speed and i just had the clutch replaced a few months ago and now it just went the other day. it is warrantied but my mechanic says the labor isnt. someone just told me that if u already payed for labor and the new clutch with a warranty that means i dont have to pay labor a second time. Is this true someone please help...think my mechanic is trying to make some extra money off me

thecardoc3

Why in the world is the clutch failed again? As far as the shop goes, doing the repair for the labor fee only has them losing money when compared to doing any other work so there is no way they are benefitting from this. But something is wrong, a clutch should last for years not months. What happened to the last clutch? Be specific.

Are you running this hard, or racing it?

Do you know what "riding the clutch" is? Are you able to hold the car with the clutch on an incline while waiting for the light to change?

neonbeast

no i always shift in nutrual.. when at stop signs or lights or hills.. im know how to drive it ..lol.. it was replaced because the place i bought it from repoed in for like 3 months when i went to go get an payed offf .. they blew my clutch as it was buried in snow i assume the rocked the hell out of it to get it out an puffffffff my clutch was broke so i replaced..... so then i drove a few months it starts makeing a noise when i stop on clutch over time it get worse.. so i stop at the garage who replaced it .. say hey its making noise when i step on clutch .. he says nooo its ur transmission .. nooooooooooo dumb asss its my clutch.. now they r blowing me offf...

neonbeast

off an my throw out baring just fell out an apart in my hand when i looked at it

lukebrown

Okay folks, here's the update. I replaced the torque converter clutch with a new one after the last one failed within a week. I replace the fluid and filter as well. Engine stalling has not been a problem as suggested before. Codes were cleared after the new one was put in, ACDelco brand.

Replaced it on Saturday and it just started shifting hard again tonight (Wednesday.) I'm beyond pissed off at this problem. The only code that comes up is the same P0742.

thecardoc3

The P0742 code means the PCM is seeing the TCC pressure switch circuit closed when the TCC clutch should be commanded off. Closed pulls the reference voltage from the PCM low (0v), and when the circuit is open you should see the 5V signal from the PCM on the yellow wire pin "U" of the transmission connector, or pin 63 of C2 at the PCM.

The first thing to do is connect a scan tool that will display the TCC release switch data pid KOEO (key on, engine off). Since a pressure opens this switch the data pid should show the TCC release switch on at that time (0v). Starting the engine, it should then show off (5v). If it shows on the whole time, then disconnect the twenty pin connector to the transaxle and see if the data pid then shows off.

A sticking TCC reed switch could cause the code to set, but the wire from the PCM to it grounding either internally or externally of the transaxle could also randomly cause the code as well.