2000 4l60 no lockup in 3rd?
12-29-2016, 11:47 AM
#1
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2000 4l60 no lockup in 3rd? Hey guys, first post.
From what I've read, my truck should lockup in 3rd (2000 Z71)
It locks up in 4th just fine. Took it a very good shop yesterday, had it road tested. No lock in 3rd per tech. 4th locks up fine with 50 rpm slip under load. He said that was fine. No other problems than 3rd lockup. Didn't really give an answer as to why.
Fast forward to today, took it to another shop, they did not road test it, told me it will NOT lockup in 3rd.
I just bought the truck 2 weeks ago from the original owner. He said it has a GM reman in it with about 100k + miles.
So the question is , is this trans supposed to lock up in 3rd?
I plan on pulling a small atv trailer tomorrow with 2 quads on it about 150 miles round trip. Just want to make sure I'm not doing any damage towing in 3rd with no lockup.
Thanks for the help in advance.
From what I've read, my truck should lockup in 3rd (2000 Z71)
It locks up in 4th just fine. Took it a very good shop yesterday, had it road tested. No lock in 3rd per tech. 4th locks up fine with 50 rpm slip under load. He said that was fine. No other problems than 3rd lockup. Didn't really give an answer as to why.
Fast forward to today, took it to another shop, they did not road test it, told me it will NOT lockup in 3rd.
I just bought the truck 2 weeks ago from the original owner. He said it has a GM reman in it with about 100k + miles.
So the question is , is this trans supposed to lock up in 3rd?
I plan on pulling a small atv trailer tomorrow with 2 quads on it about 150 miles round trip. Just want to make sure I'm not doing any damage towing in 3rd with no lockup.
Thanks for the help in advance.
12-29-2016, 02:54 PM
#2
Moderator
Welcome to the Forum. Glad you made your first post.
If your trans locks up the converter fine in 4th gear then everything mechanically is good.
Whether it locks in 3rd is controlled by the tune in the PCM. I don't know what vehicles lock up in 3rd; some do and some don't.
If you can find a tuner in your area, they definitely could tune it to lock up for you. It might cost $100, but it can be done.
I always suggest members list what city/state they live in as sometimes a nearby member will PM you to offer their help.
If your trans locks up the converter fine in 4th gear then everything mechanically is good.
Whether it locks in 3rd is controlled by the tune in the PCM. I don't know what vehicles lock up in 3rd; some do and some don't.
If you can find a tuner in your area, they definitely could tune it to lock up for you. It might cost $100, but it can be done.
I always suggest members list what city/state they live in as sometimes a nearby member will PM you to offer their help.
12-29-2016, 03:31 PM
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Well thanks for the advice.
Maybe this year does not lock in 3rd. NEITHER shop tried to tell me the tranny was shot and recommend a rebiuld.
Both said to drive it, its fine.
I'm near Charlotte NC
Maybe this year does not lock in 3rd. NEITHER shop tried to tell me the tranny was shot and recommend a rebiuld.
Both said to drive it, its fine.
I'm near Charlotte NC
01-01-2017, 07:53 PM
#4
Might be tuned also to not lock in 3rd. When I program them I set them to only lock in 4th above 55MPH but that's just how I like them. So if it's tuned there could be your answer. The trick is to look with the scanner and see if the pcm is commanding a lock in 3rd which it sounds like it is not. If it's capable of locking in 4th then mechanically everything is operating normally.
01-02-2017, 07:35 AM
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Okay, so after towing my trailer 200 miles on Saturday in 3rd gear, I'm pretty sure the converter IS locking up.
Two things I noticed,
#1 Once is shifted into 3rd the rpm would stay at 2k, yet the truck was still picking up speed. I don't know much about PWM, but I assume thats what was going on,it's so gradual i can't feel it shift.
#2 When I was crusing down the road at 65 to 70, I could tap the brake and the rpm would definitely jump up.
Now when Im driving empty, the lock up in 4th is very solid, like another gear change.
If I pull it into 3rd I never see a change. Could the converter tight enough that it is locking in 3rd, yet there was hardly any slip to begin with?
The truck has 4.10s in it, so it's not under much of a load in 3rd.
Either way, it seems like it is definitely locking up in 3rd with some weight behind it.
The only other weird thing that's going on is, it stays locked up in 4th even though the motor is lugging coming up hills at low speed, say down to 40 mph.
When it's lugging, I can see the rpm fluctuate a tiny bit.
Is that normal?
I've been reading about PWM delete. Think I will just eliminate that.
Thanks for the help guys.
Happy new year everyone.
Two things I noticed,
#1 Once is shifted into 3rd the rpm would stay at 2k, yet the truck was still picking up speed. I don't know much about PWM, but I assume thats what was going on,it's so gradual i can't feel it shift.
#2 When I was crusing down the road at 65 to 70, I could tap the brake and the rpm would definitely jump up.
Now when Im driving empty, the lock up in 4th is very solid, like another gear change.
If I pull it into 3rd I never see a change. Could the converter tight enough that it is locking in 3rd, yet there was hardly any slip to begin with?
The truck has 4.10s in it, so it's not under much of a load in 3rd.
Either way, it seems like it is definitely locking up in 3rd with some weight behind it.
The only other weird thing that's going on is, it stays locked up in 4th even though the motor is lugging coming up hills at low speed, say down to 40 mph.
When it's lugging, I can see the rpm fluctuate a tiny bit.
Is that normal?
I've been reading about PWM delete. Think I will just eliminate that.
Thanks for the help guys.
Happy new year everyone.
01-02-2017, 08:52 AM
#7
I've only consistently had mine lock in 3rd when I put the shifter in 3. If it is in Drive like normal it almost never locks in 3rd. Exception was on my Trailblazer on this one stretch of road it would tend to lock in 3rd automatically. Why I have no idea, because it never did it anywhere else, but that one road it was very happy to lol.
On a 4L60E I always recommend removing the TCC PWM function, as it is a common weak/wear point on these transmissions. Every 4L60E I get has the same shift kit combo installed to remove it along with strengthen a few other odds-n-ends, and so far, I've saved one 4L60E that was suffering and now has 170k+ on it, another had 215k when I got rid of the vehicle, and the third just hit 152k recently.
On a 4L60E I always recommend removing the TCC PWM function, as it is a common weak/wear point on these transmissions. Every 4L60E I get has the same shift kit combo installed to remove it along with strengthen a few other odds-n-ends, and so far, I've saved one 4L60E that was suffering and now has 170k+ on it, another had 215k when I got rid of the vehicle, and the third just hit 152k recently.
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01-02-2017, 09:14 AM
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I've only consistently had mine lock in 3rd when I put the shifter in 3. If it is in Drive like normal it almost never locks in 3rd. Exception was on my Trailblazer on this one stretch of road it would tend to lock in 3rd automatically. Why I have no idea, because it never did it anywhere else, but that one road it was very happy to lol.
On a 4L60E I always recommend removing the TCC PWM function, as it is a common weak/wear point on these transmissions. Every 4L60E I get has the same shift kit combo installed to remove it along with strengthen a few other odds-n-ends, and so far, I've saved one 4L60E that was suffering and now has 170k+ on it, another had 215k when I got rid of the vehicle, and the third just hit 152k recently.
On a 4L60E I always recommend removing the TCC PWM function, as it is a common weak/wear point on these transmissions. Every 4L60E I get has the same shift kit combo installed to remove it along with strengthen a few other odds-n-ends, and so far, I've saved one 4L60E that was suffering and now has 170k+ on it, another had 215k when I got rid of the vehicle, and the third just hit 152k recently.
I've seen several ways, Stiffer spring in valve,cutting a groove in the solenoid, tecpak repair valve.
Thanks for the help
01-02-2017, 05:56 PM
#9
Just a word of caution here about deleting PWM... Read what Sonnax has to say about this; http://www.sonnax.com/articles/241-2...-modifications
Further, there are some people on the interwebz stating to just put a stronger spring in there (such as the internal spring from the pump slide in the earlier/older 60E's) to stop the valve from cycling. This may work to revert the TCC clutches to on/off status only but there is another bigger problem to look at while you are in there and that is TCC Isolator valve bore wear!!!!!!!
If you are going to fiddle with this at all, and you have the valve body down I recommend going to the Fitzall valve with the o-rings on it which will seal the bore even if it is excessively worn.
I DO NOT RECOMMEND just putting a stiffer spring, or a piece of bolt in there (which I have seen while tearing down rebuilds from the "valley") as this will NOT HELP RESOLVE THE FLUID LOSS/LEAKAGE from a worn bore. If your 4L60E has 100K or more miles on it you can guarantee that the TCC Isolator valve bore IS WORN. We use a vacuum test stand on all valve bodies during rebuilds and have seen excessively worn bores on units with as little as 80K miles on them, and on EVERY SINGLE ONE that has over 100K miles on it. I have yet to see a valve body with 100K miles or more pass the vacuum test on this specific bore.
Also keep in mind that vehicles with high/higher stall SHOULD NOT be reverted to Non-PWM as you will have an uncomfortable lock-up if you go this route, in addition to a sudden RPM drop. Vehicles such as the Hummer H3/Colorado's/Canyons and Trailblazers with stock converters will suffer a very abrupt lock-up if TCC PWM is deleted. If you have a hot rod, and you don't care if you feel that sudden jolt every time the converter locks up-then go for it. Keep in mind though that on the freeway if you let off the gas to coast for a moment and then step back on the gas it is going to unlock, and then re-lock and you will continually get that little jolt every time it locks up. It gets old. Trust me on this. You will get tired of it.
The BEST plan of action for those vehicles with 100K miles or more on them is to just ream the TCC Isolator valve bore and install the Sonnax over-size valve & retain PWM function. This is my opinion though so disregard as you desire. Keep in mind that GM vehicles have proven they can go in excess of 200K with that system in place-even with leaking bores.
Further, there are some people on the interwebz stating to just put a stronger spring in there (such as the internal spring from the pump slide in the earlier/older 60E's) to stop the valve from cycling. This may work to revert the TCC clutches to on/off status only but there is another bigger problem to look at while you are in there and that is TCC Isolator valve bore wear!!!!!!!
If you are going to fiddle with this at all, and you have the valve body down I recommend going to the Fitzall valve with the o-rings on it which will seal the bore even if it is excessively worn.
I DO NOT RECOMMEND just putting a stiffer spring, or a piece of bolt in there (which I have seen while tearing down rebuilds from the "valley") as this will NOT HELP RESOLVE THE FLUID LOSS/LEAKAGE from a worn bore. If your 4L60E has 100K or more miles on it you can guarantee that the TCC Isolator valve bore IS WORN. We use a vacuum test stand on all valve bodies during rebuilds and have seen excessively worn bores on units with as little as 80K miles on them, and on EVERY SINGLE ONE that has over 100K miles on it. I have yet to see a valve body with 100K miles or more pass the vacuum test on this specific bore.
Also keep in mind that vehicles with high/higher stall SHOULD NOT be reverted to Non-PWM as you will have an uncomfortable lock-up if you go this route, in addition to a sudden RPM drop. Vehicles such as the Hummer H3/Colorado's/Canyons and Trailblazers with stock converters will suffer a very abrupt lock-up if TCC PWM is deleted. If you have a hot rod, and you don't care if you feel that sudden jolt every time the converter locks up-then go for it. Keep in mind though that on the freeway if you let off the gas to coast for a moment and then step back on the gas it is going to unlock, and then re-lock and you will continually get that little jolt every time it locks up. It gets old. Trust me on this. You will get tired of it.
The BEST plan of action for those vehicles with 100K miles or more on them is to just ream the TCC Isolator valve bore and install the Sonnax over-size valve & retain PWM function. This is my opinion though so disregard as you desire. Keep in mind that GM vehicles have proven they can go in excess of 200K with that system in place-even with leaking bores.
01-02-2017, 07:20 PM
#10
Moderator
First, welcome to LS1Tech as it appears you (Kawabuggy) just joined.
Second, Thank you (!) for detailing the issues related to converting the TCC from PWM to On/Off. And especially for discussing TCC Isolator valve bore wear.
Both the Transgo HD2 and Sonnax Performance Pack shift kits include a new TCC Isolator valve which converts to On/Off and tries to address bore wear. However, I have also long recommended the Fitzall valve because its o-ring design seals well even with a worn bore.
As mentioned, installing a stiffer spring, bolt or other gimmick is unlikely to work well, partly because the bore is still leaking. The Fitzall valve is only $18 on Amazon. Just note there are two versions for earlier ('96-'99) and later (00+) models.
Some people think they can just tune the TCC for 100% duty cycle, but again this only works if the bore is not worn.
I don't fully agree with "high/higher stall SHOULD NOT be reverted to Non-PWM".
IIRC Yank suggested PWM for their SS converters to reduce wear. And CircleD recommended going back to PWM for their triple disk converters; I did not and the engagement is noticeable although I do keep it engaged at all throttle levels.
Therefore, IMHO, a buyer should ask the converter manufacturer what they recommend as it depends upon the lockup friction material.
Unlike the general public, I think most forum members don't mind and even like feeling their converter lock up.
Second, Thank you (!) for detailing the issues related to converting the TCC from PWM to On/Off. And especially for discussing TCC Isolator valve bore wear.
Both the Transgo HD2 and Sonnax Performance Pack shift kits include a new TCC Isolator valve which converts to On/Off and tries to address bore wear. However, I have also long recommended the Fitzall valve because its o-ring design seals well even with a worn bore.
As mentioned, installing a stiffer spring, bolt or other gimmick is unlikely to work well, partly because the bore is still leaking. The Fitzall valve is only $18 on Amazon. Just note there are two versions for earlier ('96-'99) and later (00+) models.
Some people think they can just tune the TCC for 100% duty cycle, but again this only works if the bore is not worn.
I don't fully agree with "high/higher stall SHOULD NOT be reverted to Non-PWM".
IIRC Yank suggested PWM for their SS converters to reduce wear. And CircleD recommended going back to PWM for their triple disk converters; I did not and the engagement is noticeable although I do keep it engaged at all throttle levels.
Therefore, IMHO, a buyer should ask the converter manufacturer what they recommend as it depends upon the lockup friction material.
Unlike the general public, I think most forum members don't mind and even like feeling their converter lock up.
01-03-2017, 02:32 PM
#11
I use the Transgo SK-4L60E kit (combined with some Sonnax parts elsewhere) for the TCC PWM elimination. It replaces the valve entirely with a different one, and fixes/bypasses a worn bore within reason as my 1998 car had the worn bore problem (others I fixed as preventative so their bores were still fine).
I'm not sure what the Transgo one looks like compared to the Sonnax one, but it works, never had trouble after over 150k combined miles, isn't harsh applying, so you know what, I keep using it because, well, it works!
This is only for a stock converter, don't know about aftermarket ones.
I'm not sure what the Transgo one looks like compared to the Sonnax one, but it works, never had trouble after over 150k combined miles, isn't harsh applying, so you know what, I keep using it because, well, it works!
This is only for a stock converter, don't know about aftermarket ones.