P0741 P0894 trans fault any help?
P0741 P0894 trans fault any help?
11-21-2008, 03:03 PM
I have a P0741 and P0894 which are hard shift and torque converter lock up fault.. The truck occationally shifts hard but is not consistent and the torque converter locks up in overdrive as verified by the rpm incruise.
I have no clue other than cleaning the connectors on the trans...
Any other suggestions?
11-21-2008, 03:50 PM
I would clear the codes and see what happens, see the link. http://service.gm.com/gmspo/mode6/pdf/2006/2006trans5_a%20.pdf
11-21-2008, 04:05 PM
Thanks Max.. I cleared them a couple of times and they came back after 20 or 30 minutes of driving..
That GM chart indicates the thresholds for the detection can be changed.
Extending the window?
11-21-2008, 07:32 PM
Those codes point to something going on the trans controls, internally. You may have to have a full function trans scan to pinpoint the problem.
11-22-2008, 01:21 PM
check the tcc enable solenoid for a crack,very common on these. I've done afew.if the tcc enable solenoid has a crack it will cause a hard shift and cause p0741 to set also.you have to remove it and check for any cracks,the old solenoid will be brown in color the updated one will be white.if it is white these solenoids don't exhibit cracking,the brown ones do.if it has a white tcc enable solenoid the problem may lie somewhere else.here is what the solenoid looks like.http://gsi.xw.gm.com/image_en_us/gif/000/001/756/1756043.gif
11-24-2008, 10:07 AM
I assume that it's located in the valve body and will be evident when I drop the pan.. Whats that little jewel run? Pricey? It dosen't look like an orielly stocked part..
Thanks for the help guys..:wink:
12-30-2008, 07:52 PM
I ordered up the TCC solenoid for an 06 Trailblaser 2wd.. This is what they gave me.. Looks different from the original.. Do you think this a new inproved design or the wrong part?
Thanks for he help
12-30-2008, 08:30 PM
These parts are constantlty updated, remember you still have not really diagnosed this. Get the old one out and see if it works using jumpers off the battery.
12-30-2008, 09:14 PM
Thanks Wedge.. Other forums I've read say the TCC enable solenoid leaks internally also.. For 40 bucks I'll throw it in..
The instructs on this part say 200 R4 or 700 R4... I also measured the dimensions and they seem to match up.. The BWD p/n is S9811
I call a trans shop tomorrow to verify b4 I splice in...
01-03-2009, 07:33 PM
After 700 miles............... no faults, no hard shifts..
Thanks Brian... Easy fix.......... saved lots of dineroes!!!:naughty:
This is brown looking solenoid that is defective..
01-03-2009, 08:10 PM
Well done, worked out good, on rwd trucks this is a fairly easy part to access and you can see what was wrong, fwd another story
01-03-2009, 08:38 PM
I'm glad I could help,FYI I would not have cut and spliced the new solenoid because if the wires come loose the trans wont shift,causeing you to go back in and start fixing again,I would of put the whole harness in and do it 1 time and be done with it,also have the TAP reset in the trans with a tech 2 because if you don't reset the shift points this vehicle will learn the wrong shift points and possibly start shifting hard. just my 2:2cents: and from having so many years woking at a GM dealer I've replaced alot of these and I've seen alot of disasters,I would have this done. just my opinion I hope it works and glad it helped.
01-04-2009, 12:42 AM
thanks.. the new solenoid came with 2 inches of wire "pig tails"... Not much to work with.. It also came with some splices but I opted for using the splices we use on jet aircraft wire harnesses. .. high temp.. where do I go to have the tech 2 done? Any trans shop?
It seems to shift at the normal trip points..
01-04-2009, 09:49 AM
The trans will learn your " driving" habits, the relearn is built in to the pcm, there are shift quality updates for your pcm though and that is where the Tech11 is required.
01-04-2009, 12:34 PM
actually it wont,here is what reseting the TAP does:The 4L60-E transmission utilizes a line pressure control system during upshifts to compensate for the normal wear of transmission components. By adjusting the line pressure, the transmission control module (TCM) can maintain acceptable transmission shift times. This process is known as "adaptive learning" or "shift adapts" and is similar to the closed loop fuel control system used for the engine.
In order for the TCM to perform a "shift adapt," it must first identify if an upshift is acceptable to analyze. For example, upshifts that occur during cycling of the A/C compressor or under extreme throttle changes could cause the TCM to incorrectly adjust line pressure. When an upshift is initiated, a number of contingencies, such as throttle position, transmission temperature, and vehicle speed, are checked in order to determine if the actual shift time is valid to compare to a calibrated desired shift time. If all the contingencies are met during the entire shift, then the shift is considered valid and the adapt function may be utilized if necessary.
Once an adaptable shift is identified, the TCM compares the actual shift time to the desired shift time and calculates the difference between them. This difference is known as the shift error. The actual shift time is determined from the time that the TCM commands the shift to the start of the engine RPM drop initiated by the shift. If the actual shift time is longer than the calibrated desired shift time, a soft feel or slow engagement, then the TCM decreases current to the pressure control (PC) solenoid in order to increase line pressure for the next, same, upshift under identical conditions. If the actual shift time is shorter than the calibrated desired shift time, a firm engagement, then the TCM increases current to the PC solenoid in order to decrease line pressure for the next, same, upshift under identical conditions.
The purpose of the adapt function is to automatically compensate the shift quality for the various vehicle shift control systems. It is a continuous process that will help to maintain optimal shift quality throughout the life of the vehicle.
<A href="http://gsi.xw.gm.com/si/cellHandler.do?cellId=75304&refDoc=660135&from=ur#ss1-1459535">Clearing Transmission Adaptive Pressure (TAP)
Transmission adaptive pressure (TAP) information is displayed and may be reset using a scan tool.
The adapt function is a feature of the TCM that either adds or subtracts line pressure from a calibrated base line pressure in order to compensate for normal transmission wear. The TAP information is divided into 13 units, called cells. The cells are numbered 4 through 16. Each cell represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 16 is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative numbers. This indicates that the TCM has adjusted line pressure at or below the calibrated base line pressure.
Updating TAP information is a learning function of the TCM designed to maintain acceptable shift times. It is not recommended that TAP information be reset unless one of the following repairs has been made:
• Transmission overhaul or replacement
• Repair or replacement of an apply or release component, clutch, band, piston, servo
• Repair or replacement of a component or assembly which directly affects line pressure
Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the TCM will need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. Learning can only take place when the TCM has determined that an acceptable shift has occurred. The TCM must also relearn TAP values if it is replaced.I would follow this info,GM puts this info out so repairs can be fixed wright,I;ve always followed this info and it's never steered me wrong,I pass on this info for people in this forum can better understand and use this info.I've repaired plenty of transmissions and when I don't reset the tap and follow info I have a comeback,you can follow my advise if you choose.you can either go to the dealer and have the tap reset or a trans shop,they should be able to reset the tap also.
01-04-2009, 03:44 PM
None of the listed functions is really affected by the tcc on/off solenoid. What about all the tsb's for trans shift" feel" and hard shift issues, is this a relearn or in effect an actual operating change? The solenoid replacement is not listed/required for the TAP, no? It would seem since line pressures, apply pressures and internal clearances are not altered in this case that the tap would not really affect anything.
01-04-2009, 06:54 PM
to answer your question the tcc solenoid commands line pressure,it increases/decreases as you accelerate.plus it states any component that affects line pressure the tcc solenoid affects line pressure.when you look up the replacement of the tcc sol it states at the very end after replacing relearn the tap.it's a relearn of the opeating range,as the trans wears it will command higher line pressure to keep the trans shifting smooth and normal.if the tap is not reset and relearned it will maintain old shift points,which will be correct at this time but as the trans wears it wont command full line pressure because it has not learned it.also the tcc solenoid might have had an internal leak so it's gonna increase line pressure to maintain a good shift pattern,now that it was replaced it should decrease line pressure,but it won't because the trans dosen't know the tcc was replaced so it might still try to command full line pressure thinking the tcc is still bad so thats why you should reset the tap. plus if reseting the tap wasen't a big deal GM diagnostics would not tell you to relearn it? am I wright or wrong? this person might not feel any difference wright now but this could cause problems later down the road as the trans wears. I believe in doing a job wright the first time and only once. I gave this advise so this person would fix it and not do it possibly a second time.I always follow these diagnostics to the very end and when I do I have no comebacks and nobody mad at me for a sloppy job. this info is something to keep in mind,if people don't want to follow it thats ok I don't force my info. thanks brian
01-04-2009, 09:03 PM
Your info is extremely thorough having the advantage of access to GM up to date dealer info. I didn't realize the solenoid itself had any control over apply pressure, but recieved commands from the pcm that in itself it had no control over tcc apply pressure assuming proper function of course, Yes I see based on possible leakage same as the worn tcc valve body bore would leak apply pressures, the pcm would increase its adaptive working pressure.
01-05-2009, 11:55 AM
having GM info is only half,I know this from hands on experence,all my GM training,my schooling and working on these vechicles day in and day out.I take pride in repairing GM vehicles.I'm always trying to improve and learn.I post this info to help and educate others not to mislead. thankx for your time and understanding,feel free to ask any other questions. brian
01-05-2009, 03:49 PM
I am not challenging your statements I just am trying to understand how the PM " thinks" based on sensor inputs , and what it does as a result, again good info.
01-05-2009, 09:57 PM
Yeah.. Great info Brian... I understand thoroughly how the TAP can be "compensating" for a leaking TCC solenoid and the system needs basically to be re "indexed" after replacement...
I'm a Boeing 777 tech and follow "FIM" charts ( fault isolation manual) to the tee.. Some of these are over 20 pages long...
Thanks Again... We on the forum appreciatiate your info..:smile:
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