Tach bounces up and down a few hundered rpm while cruising in lockup:
Another common problem / concern of this transmission and more pronounced with added engine power or higher mileage.  This generally happens when the valve body has excess wear in the TCC valve area.  Excessive fluid leakage in this area of the valve body causes TCC apply pressure loss and can lead to uncontrollable TCC operation which causes the engine rpm to bounce up and down a bit.  This problem is noticed most after driving a while and speeds between 42 and 70mph and in 4th gear.  There are other causes to this problem that can be from worn or shrunken teflon seals on the input shaft, a bad o-ring on the input shaft that seals in the torque converter, a faulty torque converter clutch, and even a bad pressure control solenoid.  Another common occurance is a worn out sleeve in the channel plate that supports the input shaft.  When this sleeve wears the input shaft will get chewed up where the sealing rings are and cause problems.  Commonly code P0741 will be found in the pcm memory as a stored code and is described as Torque Converter Clutch Stuck Off.  When this happens adaptives shifts are disabled, TCC operation is disabled, and 4th gear can be disabled.  Generally a new or reman / repaired valve body will correct this condition and a new EPC solenoid is always suggested as well.  The TCC/PWM solenoid is rarely ever at fault and I am yet to find one bad.  Again the valve body is the common cure BUT not always the culprit and certainly not the whole problem after this has been happening for a while.  Any time a torque converter fails there will be debris going back into the trans.  There is a pressure relief valve in the channel plate that will collect debris from a bad torque converter and reduce cooler flow, cause trans to run hot, and greatly effect TCC operation and can destroy a new converter in a matter of miles if this isnt carefully inspected or upgraded.  The best way to verify proper operation as commanded by the pcm is with a scan tool by viewing TCC slippage rpm, TCC duty cycle, EPC data, and checking any codes and making sure the engine is running properly and a misfire is not a false sense of a torque converter problem or shudder.


No 4th Gear:
Again a common problem with this transmission until GM made an upgrade in later models.  There is a clutch hub inside this trans for 4th gear and has a long hollow shaft with splines on one end, and lugs on the other end for 4th clutches to key into.  The splines on the small end will turn razor sharp over time and eventually wear off.  This is more common in the 3400 powered cars but does happen in all of them.  Constant in and out of 4th gear and lockup in 4th gear puts stress on the splines with constant hammering back and forth from driveline load change puts a lot of stress on the splines.  Later GM parts as well as the aftermarket both offer a 4th clutch hub with heat treated splines which eliminates the problem.  Fortunately the transmission has to be taken half way apart to to get to this and is quite a chore to do in the vehicle though it can be done. 


Trouble Code P0742 TCC Stuck ON:
When this trouble code is set the pcm will command max TCC and lock adaptive shifting.  This code can be broken down into three potential problem areas as found to be common in the field.

1.  This problem can be a mechanical problem.  Possible causes of this could be a bad or stuck TCC switch that signals the pcm of current TCC operation.  Another cause though not common is a stuck TCC switch or apply valve.  If it is physically stuck in the wrong position it can cause the TCC to be stuck on all the time and even kill the engine when the vehicle is put into gear.

2.  This problem can be found to be an electrical problem.  If the wire from the TCC pressure switch to the pcm is grounded anywhere in the path it can throw this code.  This could be a wire shorted inside the trans on the internal wiring harness or the actual engine wiring harness.  If the wire is grounded the pcm thinks that TCC is on when it shouldnt be and will throw the code.

3.  This problem can be a hydraulic problem.  This is the most common cause of this code that I have found and stems back to a clogged TCC solenoid, not because it failed.  Excessive debris in the transmission or a failing torque converter lockup clutch can cause the solenoid to have debris stuck inside and this causes a restriction in fluid flow through the solenoid.  If the solenoid can not bleed off the pressure the TCC can be stuck on.  If the wrong TCC solenoid is installed during an overhaul this problem can also arise as a late 4L60E solenoid is identical but does not operate the same and acts like a clogged solenoid.  As mentioned in problem #1 a stuck TCC apply valve is a physical problem but causes a hydraulic problem because the fluid pressure will not properly bleed off because the valve is stuck in the wrong position instead of being able to move freely in the bore of the valve body.

Above are the common causes of this code, there are other possibilities but those are what generally causes the fault.  A thorough diagnosis is the only way to determine what is really at fault and a new TCC solenoid should never be assumed as the actual problem until verified.



Excessive gear / grinding noises while moving:
This can be a number of different things but is commonly the input carrier and sun gear which sits inside it.  I have found this problem to be worse in the 1999-2001 models and can happen for no reason even on a low mileage transmission.  It will start as a grinding noise that changes sound with speed and turns into crunching noises and finally loss of gears and all movement depending how far it goes.  A lot of fine hard bits of metal will likely be in the pan or filter and a complete overhaul is the only remidy for this.  Another cause of this noise can be a differential failing.  The planet gears on the differential that sit inside the internal ring gear in the tail of the transmission can become very pitted and chip under high mileage and excessive stress and this can also happen if any debris is in the trans and travels through the cooler and back into the geartrain.  Sometimes replacement of the differential can cure this, but normally the internal ring gear is damaged as well which requires complete overhaul.


Intermittant Harsh Shifting / Pump whining, Possible Code P1811:
This is perhaps one of the most common problems with this transmission.  It has been a problem since the release in 1997 and can happen for no reason at all even with clean fluid and very low mileage.  The EPC solenoid is probably bad and again is very common to happen.  The EPC solenoid controls line pressure and has a spool valve which oscillates back and forth to regulate transmission line pressure based on commanded pcm signals dependant on lots of various inputs of the vehicle.  The spool valve in the solenoid will bind up and cause loss of pressure control from the pcm.  The pcm constantly monitors shift timing in milliseconds and if this is not within programmed parameters after a few shift cycles the pcm triggers trouble code P1811 which is Max Adapt /  Long Shift.  This code will not set the SES light but will dissable all adaptive shifts and will max out line pressure in the transmission which causes the harsh shifts and can also cause the transmission pump to whine because it is supplying fluid at a high rate and pressure and puts more stress on it thus creating the whine.  Generally shutting off the car will make this condition go away until you drive a few more miles or the vehicle warms up and the harsh shifting will return.  Replacing the EPC solenoid will most likely correct this condition and again is probably the most common problem found in any year of this trans.  I will also add that a worn out transmission can cause this.  If the fluid looks bad, dark, and smells burnt or lots of fine dark sludgde or a dark film of material is in the bottom of the pan then there is probably internal damage.  Once clutches become burnt and have excessive wear shift timing will be greatly extended and the pcm will fall outside of its set parameters and code P1811 will turn on, again commanding higher line pressure and harsh shifts but an overhaul in this instance is the only proper fix.


Loud Whining, changes with engine speed:
This is another common occurance in this transmission and has a lot of different possibilities.  There are a number of different bearings that can fail inside the transmission and each one will dictate when the noise is happening.  There is a thrust bearing inside the torque converter that can also make a whining noise and is loudest under a heavy load.  Generally that bearing will get louder each time the transmission shifts into a higher gear and the converter has to work harder and puts more stress on it.  It wont make noise at idle or in neutral unless the entire torque converter is in very bad condition and has lots of metal in it.  The most common bearing whine noises comes from the roller bearings that support the drive and driven sprockets which the drive chain rides on.  They will make noise any time except sitting still in any gear, that is because nothing inside the transmission is spinning at this time.  In park and neutral they do spin and when the noise is most visable.  There are quite a few other bearings inside the trans but these are the common ones found bad.


Solenoid and or Valve Body replacement:
This is a very commonly asked question.....  How hard is it or is it something I can do in my garage?  The answer will vary depending on mechainical skills and your tool supply!  Because this is a front wheel drive transmission and the arrangement of the internals you CANNOT simply drop the bottom pan and access any of the solenoids or the valve body.  In order to gain access to the solenoids and / or the valve body you must lower the transmission out the bottom of the vehicle.  Every different vehicle line is arranged different so I cannot provied information that is specific to all models.  You will need to have some sort of engine support device as the engine must be held up  because you will be dropping down or removing the support cradle under the front of the vehicle which contains engine and transmission mounts that support the drivetrain.  On some vehicles you must remove the cradle complete out from the vehicle while some you can just remove a section of the support cradle.  You also may be required to completely remove the transmission from the vehicle while most you should be able to use your engine support and lower it down enough to remove the side cover of the transmission.  You have to remove the side cover of the transmission to gain access to the solenoids and valve body.  Often times you can reuse the side covert gasket, but if it is damaged you will need to replace this item and it is a dealer only part that is pretty costly, so be careful with the original!  Before you remove the side cover you will need to drain the transmission fluid.  You will also need to remove the drivers side axle, unless you plan to just leave it hang from the axle but often there is not enough room to do this because of suspension components.  Once the side cover is off you will have full access to inspect / replace the solenoids, pressure switch manifold, and pump/valve body assembly if needed.  This is a very labor intensive job and a $50 solenoid can quickly turn into a $500-$1000 job depending on vehicle and shop labor rate, so even though it is hard to gulp a quote that you recieved from a shop it is certainly expected once you know why it is so much and the labor needed to do the repair.  This is something that can be done with patience and the right tools and a good mechanical aptitude.  Though an experienced trans shop or a tech can do this in roughly 4-8 hours I would plan a full day or two worth of down time.  Even if everything comes apart smooth you can run into other problems along the way or find more problems than originally sought out.  I hope this helps in the understanding of what is involved to make in car repairs,  for specific vehicle information I would recommend contacting a local shop or finding a repair manual for your vehicle. 




The myths of the Deadly Trans Flush:
This is one subject that leaves a lot of people in mistrust, doubt, wrongful information and a bitter feeling when mentioned.  First of all let me clarify what a transmission flush REALLY does since it is very commonly misunderstood.  A transmission fluid flush machine does nothing more than hook up in line with your transmission cooler.  One line hooks up to the supply coming from the trans and the other line hooks back up to the return side, which is in series with the cooler.  This IN NO WAY flushes the inside of the transmission!  All it does is take the old fluid from the transmission side out and replace what goes back in with fresh new fluid.  There is no magic wand that crawls inside the transmission and pressure washes anything to disturb particles and gunk buildup.  The transmission fluid flush machine has a bladder inside that transfers existing pressure that comes out of the transmission, roughly 10-40 psi, and passes it along to the opposite side of the bladder containing new fluid to properly displace the same amount that came out.  NOW with that said here are some problems.  I have seen many times where a shop did a flush and NEVER checked the trans fluid before OR after the flush!  I have found cars up to 4 quarts low on fluid because of this neglect and leaving the customer stranded with a burned up transmission.  It is more of  a user or operater problem than the machines fault, its just putting back in what came out.... or is supposed to.  During transmission fluid flushes there is also an additive that commonly is added before the flush to help clean the inside of the trans and can be harsh if the transmission has been very neglected over its life.  After a transmission ages, and the fluid ages respectively, things chemically change inside the trans as far as friction materials and the adhesives on them.  If you never change your trans fluid and it has very high mileage on it or is severly burnt then NEVER expect a flush to magically cure problems or expect new fresh fluid with strong detergents not to cause problems.  It is a shock to the transmission to remove all of the old well past due fluid with all new fluid and the new fluid with its fresh strong detergents can break down the friction materials and adhesives that bond them to the clutch plates.  On a vehicle with higher mileage and an unknown past it is always much safer to drop the pan and change the fluid and filter, that way you are giving the fluid a chance to slowly adapt, new with old and not be such a chemical shock to everything.  Again checking the fluid level is a MUST!  Neglect is the biggest problem with transmissions and making sure the fluid level is full and periodically serviced is the best you can do for it.  Another problem is that new transmission fluid has friction modifiers in it and tend to keep shifts smooth.  A lot of times if you change trans fluid that is old and burnt with new fluid it will feel like it is shifting softer, that is because the fluid is doing its job again.  Fortunately on computer controlled transmission this can be troublesome since the pcm controls shift timing and now has to play catchup to firm up shifts because it has been softening them up over time.  Not a common occurance but again neglect will only lead to worst case scenarios.  I have nothing wrong with flush machines IF used properly and not used on a trans that is just plain worn out, again it is not a solution fix all, it is maintenance pure and simple and if neglected too long then only time will tell longevity of the trans.  I hope this clears up some of the confusion and mislead information that has been floating around for years.  I have NEVER seen a flush machine cause a failure, I HAVE seen an operater of a flush machine cause a failure.


I hope you find this information helpful and I will keep adding more as I can.  Again for anything not mentioned above or something you feel should be added please email me.  For those looking to explore the inside of their own transmission and make your own repairs please click on the 4T65E PARTS link at the top of the page for parts info and pricing.