Auto Trans Issue
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Joined: Feb 2010
Posts: 66
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From: Seoul
Auto Trans Issue
My 2001 auto coupe doesn't want to shift into third at low RPMs. If I accelerate hard it will go to redline without shifting. When I let off on the throttle it will shift into third. If I accelerate slowly it will shift but not until it gets to about 4k. It has power in 2nd, it just wont go into 3rd like it should.
Am I losing a clutch and facing a costly rebuild? Or, please, could it be something else?
Am I losing a clutch and facing a costly rebuild? Or, please, could it be something else?
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The VERY FIRST thing that you have to do is see if you have any DTCs set for the transmission. Enter the DTC reading routine and list ALL the DTCs that you have. Especially the P series DTCs.
My guess is that you have a shift solenoid issue and it could be a blown fuse or bad solenoid. List the DTCs and that will get us started on getting this resolved.
BC
My guess is that you have a shift solenoid issue and it could be a blown fuse or bad solenoid. List the DTCs and that will get us started on getting this resolved.
BC
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From: Hickory NC
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St. Jude Donor '17 thru '26
First: Have you done any work to the trans or had anyone else do any trans maintenance? Have you had a recent tune performed that could have affected the shift points/pressure?
Second: Have you checked for DIC codes? If the problem is electrical (solenoid) it could reflect there.
Third: Have you checked your trans fluid level? A possible inexpensive fix attempt would be to change the fluid and filter. Long ago, there were issues that the filter could have gaps that would keep it from maintaining vacuum which would then reduce the fluid pressure in the transmission.
If the transmission fluid level is full, does it smell burned? This could represent something overheating in the trans; quite possibly the 3-4 clutch pack.
Hopefully it is just low fluid or even the servo which is still a cheap fix. If not, you may be right about a rebuild. Ouch.
Oops: Just saw Bill Curlee beat me to the punch about the solenoid.
Second: Have you checked for DIC codes? If the problem is electrical (solenoid) it could reflect there.
Third: Have you checked your trans fluid level? A possible inexpensive fix attempt would be to change the fluid and filter. Long ago, there were issues that the filter could have gaps that would keep it from maintaining vacuum which would then reduce the fluid pressure in the transmission.
If the transmission fluid level is full, does it smell burned? This could represent something overheating in the trans; quite possibly the 3-4 clutch pack.
Hopefully it is just low fluid or even the servo which is still a cheap fix. If not, you may be right about a rebuild. Ouch.
Oops: Just saw Bill Curlee beat me to the punch about the solenoid.
Last edited by Route99; Nov 9, 2018 at 12:44 PM.
Thread Starter
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Joined: Feb 2010
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From: Seoul
Fluid check
I'll get it to the lift and check the fluid. I might as well change it while it's in the air. I changed it when I got the car at 115kmiles. It's at 154k now. I was going to do it at 165k (50k between changes) but if it could be an inexpensive fix it's worth a try now. Thanks
Instructor
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From: Dallas Tx
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Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
WARNING!!! REFERENCE THE SERVICE MANUAL for the exact procedure . If you do the check/fill procedure wrong, you could damage the trans and or BURN your self if the oil is hot!.
Drivers side of the trans on the pan. ENGINE MUST BE RUNNING when you remove the fill plug and or add fluid!!!!!!!!!!!
Drivers side of the trans on the pan. ENGINE MUST BE RUNNING when you remove the fill plug and or add fluid!!!!!!!!!!!
Drifting
Joined: Feb 2008
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From: Bahama North Carolina
Make sure they are aware of the correct fill procedure. Sadly some shops are not. Some trans shops have never worked on a C5. The service manual will have you drop the pan and change the filter along with the fluid.
Last edited by BigGun; Nov 14, 2018 at 11:36 PM.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I SECOND that recommendation. 
Even though they are a "TRANSMISSION SHOP" they might not be familiar with the CORRECT C5/C6 fill procedure. If it were me,,, for piece of mind, I would ASK.
Let us know how it turns out.
Bill
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Joined: Feb 2016
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From: Sterling Heights MI
If your fluid is not low, not leaking, and not burnt, you may be throwing away maintenance budget replacing it now, considering a rebuild is a possible need.
I'd opt for the shop to diagnose the issue rather than just throwing fluid in, potentially causing more harm than good. A scan tool should tell you the commanded gear. If third is not commanded until 4k rpm, the trans has nothing to do with this problem and you would have to look at what's causing the pcm to make erroneous commands.
If the command is simply not being followed, then something in the wiring or the trans is the issue, and you could take your diagnosis from there. A solenoid problem can be diagnosed without opening up the trans.
I'd opt for the shop to diagnose the issue rather than just throwing fluid in, potentially causing more harm than good. A scan tool should tell you the commanded gear. If third is not commanded until 4k rpm, the trans has nothing to do with this problem and you would have to look at what's causing the pcm to make erroneous commands.
If the command is simply not being followed, then something in the wiring or the trans is the issue, and you could take your diagnosis from there. A solenoid problem can be diagnosed without opening up the trans.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Switching to a synthetic fluid this late in the game is NOT going to make ANY difference. IF the fluid is not low or burnt, I would have to agree with VIPMILLER 803 in that you are wasting time and money. If its burnt, then you need a rebuild.
Another point to PONDER.. If the trans is not shifting correctly,, it SHOULD be throwing DTCs. If NOT, like VIPMILLER803 stated, you need to track that issue down FIRST!
Another point to PONDER.. If the trans is not shifting correctly,, it SHOULD be throwing DTCs. If NOT, like VIPMILLER803 stated, you need to track that issue down FIRST!
Thread Starter
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Joined: Feb 2010
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From: Seoul
Thanks guys
A scan tool should tell you the commanded gear. If third is not commanded until 4k rpm, the trans has nothing to do with this problem and you would have to look at what's causing the pcm to make erroneous commands.
If the command is simply not being followed, then something in the wiring or the trans is the issue, and you could take your diagnosis from there. A solenoid problem can be diagnosed without opening up the trans.
If the command is simply not being followed, then something in the wiring or the trans is the issue, and you could take your diagnosis from there. A solenoid problem can be diagnosed without opening up the trans.
Le Mans Master
Joined: May 2006
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From: Hillsboro OR
I just wanted to add that the FSM also states that the transmission fluid temp MUST be between 86 degrees F and 122 degrees F to get a proper level reading. I read mine when fluid was quite warm and it was full. I then waited until the fluid was at the correct temp and I found that I was 22 oz. low!!!!
