c5 auto shifting HARD into second
Thread Starter
Cruising
Joined: Jul 2013
Posts: 13
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c5 auto shifting HARD into second
Hello all.hoping for some help..today on the way home.from buying vette parts..my 1997 auto w/140,000 on it started shifting REAL HARD outta 1st.into second..never before any signs of trans issues..has anyone got any ideas..tx red
Safety Car
Joined: Aug 2011
Posts: 4,449
Likes: 409
From: Portland OR
How long have you owned the car?
Check the DTC's. There are a few that will cause the trans to go to full line pressure and it will shift hard.
Someone in the past could have disablesd the MIL (check engine) for those codes.
Likely P1870....Transmission Component Slipping
Ron
Check the DTC's. There are a few that will cause the trans to go to full line pressure and it will shift hard.
Someone in the past could have disablesd the MIL (check engine) for those codes.
Likely P1870....Transmission Component Slipping
Ron
Last edited by RonSSNova; Aug 1, 2013 at 02:03 AM.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
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From: CA.
St. Jude Donor '13-'14-'15
Your ECM may have gone into "limp mode" or power reduction mode--That can happen from either a real issue going on or a false issue that has triggered it--If the car has been running fine until then more than likely it is a false trigger---
When the ECM goes into Limp mode the tranny is commanded to have "full line pressure " 90 PSI all the time---whereas normally at P/T it would only have 30 40 PSI
The 1-2 clutch pack in your tranny is the beefiest so you would notice full line pressure there more than any other shift----
You can dis connect your battery overnight and it should re-set the ECM back in normal mode-----If it happens again then you probably have a real issue
When the ECM goes into Limp mode the tranny is commanded to have "full line pressure " 90 PSI all the time---whereas normally at P/T it would only have 30 40 PSI
The 1-2 clutch pack in your tranny is the beefiest so you would notice full line pressure there more than any other shift----
You can dis connect your battery overnight and it should re-set the ECM back in normal mode-----If it happens again then you probably have a real issue
Thread Starter
Cruising
Joined: Jul 2013
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Tx so much for the info on the c5 auto shifting hard..sleepless night waiting to see if unhooking the batt. Would solve the issue..and it did..shifts fine now..any idea why it did this?..tx again for your input n help..wes..redrocker97
Safety Car
Joined: Aug 2011
Posts: 4,449
Likes: 409
From: Portland OR
As Tom said, there are a few codes that cause the trans to go to full line pressure. Unhooking the batt cleared those codes.
Would have been nice to scan the car and see what they were.
I bet it comes back.
Would have been nice to scan the car and see what they were.
I bet it comes back.
Le Mans Master
Joined: Sep 2003
Posts: 8,847
Likes: 795
From: Longview Texas
I don't think that disconnecting the battery clears all the trouble codes from history. You might try running the diagnostics from the Driver Information Center and see what shows up..
There are instructions on the forum for how to manually run diagnostics. (press and hold Options, then Fuel 4 times quickly)
There are instructions on the forum for how to manually run diagnostics. (press and hold Options, then Fuel 4 times quickly)
