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Thread: 6L80e won't "Fast Learn"

  1. #1
    Potential Tuner NotoriousDan's Avatar
    Join Date
    Jul 2018
    Scottsdale AZ

    6L80e won't "Fast Learn"

    Got a swap project in the shop that keeps saying "Temp Lo" when I try to "Fast Learn" the TCM. Its a L83 with a 6L80e that came out of a rolled Tahoe. We put it in a 78 Scout. Have studied up on all the forums, Googles and inter web and everybody says to get trans fluid up to 170 degrees, put it in drive and click the "Fast Learn". Done it several times now and always getting "Temp Lo" for a minute or two then "Aborted". Got the trans to 180, same thing. Changed the gauge from fahrenheit to celsius, same thing. Have clicked all the buttons, checked all the levels with no luck. Truck runs fine, reverse is fine but put it in drive it seems fine but falls out of gear and seams like its searching. Going to hit it with another scan tool and see if that does the trick. Just would like it to work with my HP tuners scanner. Any input or advice would be greatly appreciated!

  2. #2
    Potential Tuner
    Join Date
    Nov 2018
    Knoxville, TN
    Interested to hear if this gets resolved.

    Have you skimmed through this already? It may only be partially relevant. It is a long read.

    I don't have a link to back this up, but I am fairly certain that GM removed the Fast Learn procedure from their Tech 2 scanners. Supposedly the Clear Trans Adapts procedure still remains. So I guess the relearn takes place as the vehicle is driven when GM services or replaces a transmission.

  3. #3
    Notorious-as Plohr alludes to, sometimes, on some vehicles you simply CANNOT do a QUICK/FAST learn. Just like you are describing, it will indicate "Temp Lo" regardless of the temperature, and then NEVER EVER allow you to do the fast learn. I've been trying to use HP Tuners to do the QUICK/FAST learns on each of the 6 speeds we rebuild at my shop. We are turning out on average 1 per day at this point... Out of every 30 you do, 1 might actually do the fast learn correctly and get to the "completed" at the end... It does not matter though.. If you do the Pre-sets, and resets, even if you can't get the FAST learn to initiate or complete, the computer will learn on it's own. It's absolutely CRITICAL that after doing the RESETS that you NOT stomp the gas pedal hard at all!!!!!!!! The trans may exhibit some flare, or soft, shifts after doing the resets and you could easily smoke a clutch pack hammering on it while the computer is adjusting the oncoming, and off-going presets/volumes. I would drive it minimum 200 miles LIKE YOUR GRANDMOTHER WOULD DRIVE IT. DO NOT stomp the pedal during that re-learn period. Then after the initial 200 miles, drive it the next 200 miles keeping engine RPM's under 5000. Then after that period, if you really feel the need, you can go ahead and hammer on it..... I don't recommend ever hammering on it but that goes against the grain here specifically, on a performance oriented web site..

    The other thing you need to do, after doing the resets, is help the TEHCM learn the R & D engagements. You do this by sitting with the vehicle idling, engine at operating temp, trans at operating temp. Move the gear shift lever into the R position and let it sit for at least 3-5 seconds. Then move it directly to D from R and then let it sit for 3-5 seconds. Do that 20 times... going back & forth between D & R, and R & D. I know, it seems crazy but at the end the engagements between gears will be perfect.

    Now, you need to do the same process as above except this time you need to go between N & D.. allowing it to sit 3-5 seconds in each position. Then do the same between R & N.... Trust me, your engagements will be perfect after doing this IF there are no problems inside the trans, and if it has the correct amount of fluid, and IF the Crappy GM torque converter has not blown up... That's another thing-get the GM torque converter OUT OF THE TRANSMISSION RIGHT NOW! Every 6L that comes into my shop comes in because of a blown up GM torque converter... Not kidding.. My shop is seeing 30 +/- 6L's a month and EVERY SINGLE ONE THAT COMES IN IS FOR BLOWN UP GM TORQUE CONVERTER!!!!! If you are running a GM torque converter, and it's not blown up yet, give it a short time and I promise you it will... We had a GS Corvette come in with 82K original miles with a blown up GM torque converter.. Typically-most GM T/C's will blow up in a full size truck between 105-150K miles.. Yes, I've seen some go much further... But out the 30 we see each month, maybe 2 will have gone in excess of 200K miles.. Yes, it is that bad... Get the GM converter OUT of your truck now unless you just want problems, and to have to rebuild your trans later... put an after-market Precision T/C with the billet cover in your truck and you will be set for a very long time.

    Lastly-beware of ANY company remanufacturing torque converters that is using the factory GM stamped T/C housings.. ONLY use T/C's for the 6 speeds that have had the billet cover installed. The problem is that the factory, stamped, GM T/C housings are ALL WAPRED... Yes I said it. The T/C remanufacturing companies do not want to tell you this... They would rather rebuild the GM housings and then when they fail again shortly after you install it in front of brand new trans-their answer is to just offer you another piece of junk rebuilt T/C with a warped T/C housing..... I have talked to one of the largest T/C remanufacturing companies in the world and they told me that they will NO LONGER SELL REMANUFACTURED T/C'S FOR THE 6L WITHOUT A BILLET COVER because they have had so many returns due to the rebuilt converters failing shortly after being put back into service. For that reason I only buy, sell, and install T/C's with the billet cover.

    I have talked to 3 different T/C rebuilding companies during my research and they all admit that they have significant defect returns on the GM B-85JMBX converters that they rebuild.. Because they are all using the WARPED GM housings!!!!!!!!!! Once you go to billet cover-NO PROBLEMS.
    Last edited by 1364838952; 06-20-2019 at 04:11 PM.