All,
my 2000 corvette began having the problem of slipping gears as accelerating and then the check engine light came on. I took to our local Chevrolet dealership who determined we were in need of a new transmission. I wish I'd researched it further back then but I was rushed and as they say "hindsight is 2020". It has been at least 3-4 months and two new transmissions later we have solved nothing. I was told that they now feel that the wrong differential was put in at some point? Mind you the car has 21,000 miles. They say that someone put in 342 gears ( manual trans compatible) instead of the 315 which should have been put in for the automatic transmission. Honestly at this point i don't remember this being done but it is possible after a friend had some repairs done.

In any case the car has been in their hands for months now and they are searching for the 315 gears that so far they can't find. This tech is above my hobby pay grade and at this point I'm not sure they know what the heck is wrong. Any help or suggestions will be welcome including helping find the gears!

Thanks in Florida!!

 

Hey, sorry to ask but I think I might need a new transmission. How much did it cost to get at the dealer (parts and labor)? You said you went through 2 transmissions, did you get the 2nd one replaced under warranty from the first that you paid Chevy to source and install?

 

You said you saw a check engine light…what was the DTC ??…funny that 2 transmissions didn’t solve your problem…you sure it’s a tranny problem but it may be a misfire which can be mistaken for a trans issue or even a TPS sensor dropping out ??…where in Florida are you located ???…if the car is still sitting at the dealership have them scan the car for all codes and let you know what the current and history codes are stored.

 

Time to find a new shop. This one has proven it isn't competent obviously. The differential has nothing to do with your problem. Your shop didn't tear down the last trans they let you blow up to figure out what happened? There is something endemic to the car that is killing your transmissions.

 

if they didn't pull codes before working on it. Run for your life. That is basic 101 but these guys aer 057 is 2 below 101 that's where i started in college. Everybody was drooling but me.

 

Even if you have 3.42 gears installed they don't have to be swapped out. You need to get a tune to fix the trans shift points. Any competent tuner could do this for you. That dealer is not competent. Depending on what year your C5 is some of the handheld tuners might be able to adjust axel ratio.

 

I swapped my auto 2.73 diff for a manual 3.42 diff and no issues. It is a common upgrade. Find a different shop.

 

Yes, going outside the normal rear drive ratio for an A4 can trigger a need to reprogram the power control module so that the transmission shifts at correct rpm and power for both wide open throttle and easy street driving. Factory A4's had 2.73 or 3.15 rear drive ratios. Either requires a specific PCM program and dealers have access to those programs. If in fact you have a 3.42, the dealer will be clueless because there is NO GM factory program for an A4 and a 3.42 rear drive ratio so the dealer will not be able to reprogram if that is the problem.

You need to be specific on symptoms. Slipping could mean that the dealer has no clue on how to fill the transmission in a C5, which requires a VERY specific procedure to avoid being low on fluid after fluid or transmission change.

My sense, take the car back and have someone who understands C5's work on it. 3.15 gears are available from MANY vendors and transmission builders, but that is not the problem.

 

No apology necessary. Yes we spent about $3900 for a new trans installed. Yes the 2nd trans was done under warranty and no further charges. It has not solved the problem.

 

Your reply is most appreciated. Tech found DTC P1870
They did tear down the trans after it continued to deliver the same code and continued to slip. Interesting you did not think the differential has anything to do with the issue. We are in SW Florida.

 

While incompetent, I'm stuck with them for the moment due to warranty. All that said they are working to try and solve the problems...

 

Thank you for teh reply, it is a 2000 Vette and I would hope they have tried the re-programming but I will bring it up. The fact that GM sent them a second trans under warranty I would think there was some discussion about the issue and it is some kind of incompatiability?

 

P1870 appears to show your torque converter blew up. "TCC" = Torque Converter Clutch. Have to find out WHY the TCC blew up. Usually its because some crap went through it. Did they get P1870 on the replacement trans that blew up too?

 

Jim,
Thank you for your reply and i have forwarded it to the service manager. I know they did something with the control module. Your suggestion is very interesting in that I would hope this had been tried but who knows...I will keep you posted and thanks again.
Wayne

 

Yes I believe it sent the same code but I'm checking. So I'm passing your suggestion along and will keep you updated.
thanks for your help,
Wayne

 

Disappointing the dealer doesn't know how to treat a car with 4L60E problems considering this trans was used in 99999999999999999999999 billion GM vehicles and "blown up" is a very common mode of operation for them...

 

If possible can u get a list of what they have done so far and post ??

 

I would pull the PCM and mail it to ECS and get a mail order tune put in it so that by the time they get it back together you have the PCM programmed for the rear gears.

At any rate, don't pay for 3.15 gears. It should cruise just fine with the PCM programmed for 3.15 gears and the car actually having 3.42 gears. It definitely should not be slipping when cruising with that gear mismatch. Just avoid any wide open throttle runs until you get the PCM programmed for the 3.42 gears. I don't think it would slip, but the shift timing will be wrong and it will likely just hit the rev limiter which might freak someone out that the transmission still has issues.

There could be a PCM or wiring problem if it set the same code again. But then maybe they didn't replace or clean the transmission cooler properly or they tried to re-use the torque converter, which you should never do when rebuilding a transmission. A TCC code and the thing slipping are different faults, but could have been related as in the one failure cascaded into causing the other failure.

 

I've been running a 3.42 diff in my 2000 C5 A4 for 16 years!! Originally a 3.15, G92 optioned car. In my opinion, it sounds like the lock-up clutch, the TCC, has dumped contaminates thru the entire valvebody and trans. Did the dealer install a new torque converter? They should have, especially for $3,900!!!! It sounds very much like my old 700R4 (The grandfather of the 4L60E) did when the TCC went out. My trans guy said if I put a new/rebuilt tranny in, and kept the old converter, I'd basically be reinstalling the problem, and the new/rebuilt tranny would soon be junk, as whatever junk was still in the converter would soon be flushed into the 2nd tranny. Think of it as rebuilding the engine, when the oil pan is pull of metal shavings, and then pumping the junk thru the replacement engine. The A4 back then didn't have much of a trans filter. It DID have a big magnet in the pan. You shoulda seen that magnet!!!! It looked like it was 4 or 5 inches in diameter, when it was less than half that size. All due to it grabbing all the metal shavings. Please keep us posted, and best of luck........

 

This is a very active post, is it alright to chime in and ask a different but similar question about a 3.42?