I recently bought a '97 GMC Sierra Z71 pickup truck and need some advice here from somebody that knows transmissions better than I...I found a Z71 board on the internet but it's a new site so there's only 5 members including myself so no one has offered any advice; that's why I'm asking here. Two days after I got the truck the SES light came on and I read the code--P1870 (transmission component slipping). I did an internet search on the code and found out that it is a common problem with the 4L60E transmission, and is caused by the TCC valve wearing out. The fix is to either bore the cylinder out and install an oversize piston or replace the valve body altogether. I bought a rebuilt valve body for $90 shipped but have not put it in yet. Then I found out that the transmission was overhauled just less than a year ago and had a 2-year warranty, meaning there is just over a year left on the warranty. Problem is, the shop that did the work is almost an hour away from me so getting the truck there and getting a ride back home could be a problem. I talked to the shop on the phone and told them what I had found out and they would not acknowledge that there was any such problem with this type of transmission. BTW, I have not had any drivability issues whatsoever but the fluid is starting to smell burnt. It did not smell burnt when I picked the truck up, but for all I know that may have been freshly changed fluid. My questions are, should I bother with this shop that is that far from me if they couldn't build the transmission to last any longer than it has without any issues in the first place? Do you guys think this transmission would be OK if I replace the valve body and do a couple of fluid/filter changes to clean it up, or is it toasted already? The guy I bought the valve body from said if it came down to needing a transmission I could pull it and he would meet me halfway between where I live and where he lives (I'm in Ohio and he's in Indiana) and I could swap it for a trans that is rebuilt a bit better than stock for $600 so I'm hoping if I decide to not pursue the warranty this transmission will at least get me through the winter. What do you guys suppose I should do? Thanks in advance...
Need non-TR transmission advice...
- Thread starter JST A 6
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I reccomend asking in this forum. There are a few trans builders that are very knowledgable on the 4L60E. Crosley is 1. You may find what you're looking for there if you do a search in the forum for the problem code.
Hotrodders Bulletin Board - Transmission - Rearend
Hotrodders Bulletin Board - Transmission - Rearend
novaderrik
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there uis a rather large board out there dedicated to every GM pickup built since 67- but i can't remember what it's called right now. i'm talking tens of thousands of members here, and they know their stuff.
alos ask around on 4th gen F body boards- they also used the same trans from 94-02, so that might be a good place to look, as well. and the Impala SS guys have some experience with them, as well.
google is your friend here..
alos ask around on 4th gen F body boards- they also used the same trans from 94-02, so that might be a good place to look, as well. and the Impala SS guys have some experience with them, as well.
google is your friend here..
Thanks for the advice guys, but I belong to too many boards already...:biggrin: I'm already having a tough time keeping up with them all. I was just looking for opinions from guys who know automatic transmissions in general, as to whether they think my transmission can be saved without an immediate rebuild or is it too late? I finally got a hold of somebody who's willing to follow me out to the transmission shop and give me a ride back home, so depending on what the shop says and does, and how thoroughly they do it, I may still need to know if changing the valve body and fluid/filter will be enough to get me at least through the winter before I have to have a rebuild done or replace the transmission. By changing the fluid/filter, I mean also drilling & tapping the convertor for a drain plug and changing the fluid/filter a couple of times to get as much contaminated fluid out of the transmission as possible. Any more thoughts on this would be greatly appreciated...
Thanks
Thanks
I think it's a little premature to condemn the VB before the transmission could be better evaluated by an expert.
You stated that the fluid is burnt. The transmission will need to come out.
A tech that knows his stuff should be able to determine from test driving and scanning the ECM whether the slippage is a friction element in the trans or the torque converter clutch. TCC slippage is most likely. The suspect bore can be easily inspected to see if bore wear is the cause. If the fix was already done to the VB, then the problem is elsewhere and it doesn't make sense to throw another VB at it. Testing and inspection is what's required.
Check that the right TCC lining was used also. It must match the style of TCC control your model truck was produced with. Simple on/off control or PWM control. The wrong lining in a PWM application will not last long.
You stated that the fluid is burnt. The transmission will need to come out.
A tech that knows his stuff should be able to determine from test driving and scanning the ECM whether the slippage is a friction element in the trans or the torque converter clutch. TCC slippage is most likely. The suspect bore can be easily inspected to see if bore wear is the cause. If the fix was already done to the VB, then the problem is elsewhere and it doesn't make sense to throw another VB at it. Testing and inspection is what's required.
Check that the right TCC lining was used also. It must match the style of TCC control your model truck was produced with. Simple on/off control or PWM control. The wrong lining in a PWM application will not last long.
Well, I managed to find a ride so I could get the truck dropped off today, so for now I am leaving it in their hands. The TCC control is PWM; and like I said before when I did my research on the fault code that was set I turned up a ton of information on the problem, including a couple of .pdf files that tell about it so I could post them as attachments if anybody cares to see them. The thing that bothers me is that after all the info I found on the problem, the transmission shop denied having heard of such an issue when I talked to them on the phone late last week so I'm a little worried that they may just fix the symptoms rather than the actual problem. I guess what I'll do is let them have their way with it, and then check the condition of the fluid very frequently, and if it ends up smelling burnt or throwing a code again I'll let them "fix" it one more time then get it home and change the valve body. I just hope by that time I don't have to lay in the snow under the truck to do it...
Your converter should have a DCNF or DHHF code on it for use in the Pulse Width Modulation lockup that these use. If an earlier conveter like a DG*F, then it will slip and destroy itself. These are carbon fiber woven clutches and are made for the modulated apply where as the paper clutches get glazed and then slip. If the trans shop was good, they should know all about the 1870 code. In the shop I used to work at before Toyota, we used to do at least 3 of these a week for almost the full 12 years I was there. I was the builder there the whole time and if the valve body was worn out, we would reem out the valve body and install the bigger valve during overhaul. A few times we found the input shaft was worn where the Oring for the lockup clutch is and have to replace that even after someone else had just overhauled it. Lots of people overlook the input shaft. Even one dealer here had a lawsuit brought against them because they overlooked little things.
I would find another shop since it sounds like they are going to give you problems already with their attitude.
I would find another shop since it sounds like they are going to give you problems already with their attitude.
Thank you for this info. I thought I was onto something just because of the amount of info I had found on it. Since the transmission is under warranty at the place I took it to, I'll let them look at it and see what they say they did afterwards. After that, if I have more trouble I'll probably end up swapping the transmission for one that's built by somebody who knows what they're doing, such as the guy I got my valve body from that hasn't been installed yet. Like I said before, he said he'd meet me halfway and do the swap for $600 plus he knows about the P1870 trouble code and the problems people have had with these transmissions--that's his whole reason for selling the rebuilt valve bodies. Just for the heck of it, here's a link to a valve body being sold by the same guy I purchased mine from:
eBay Motors: GM 4L60E VALVE BODY + GASKETS + INFO + TECH SUPPORT (item 140273280008 end time Oct-13-08 05:42:36 PDT)
That price is because I'm dealing with a guy that's doing it on the side, rather than going through the shop he works for. I plan to find out what sort of guarantee he offers if any, but I guess his feedback on eBay probably says a lot about his work too. Plus, this is basically a stock rebuild with exception of a stronger sunshell. I can't remember if he said a convertor was included in that price or not, but I'm sure if it's extra it won't cost nearly as much as what I'm looking at spending to get a convertor for my Buick (that's a whole other problem I have to deal with
)That price is because I'm dealing with a guy that's doing it on the side, rather than going through the shop he works for. I plan to find out what sort of guarantee he offers if any, but I guess his feedback on eBay probably says a lot about his work too. Plus, this is basically a stock rebuild with exception of a stronger sunshell. I can't remember if he said a convertor was included in that price or not, but I'm sure if it's extra it won't cost nearly as much as what I'm looking at spending to get a convertor for my Buick (that's a whole other problem I have to deal with
Yeah, that was going to be my next question. What recourse you have if there's a problem. In Cali, someone working without a business license out of his house, you'd be screwed.
Don makes perfect sense. I do side work out of my house too but I take pride in my work and I keep track of what I do to each transmission, parts and mods done. I offer a 1 year warranty and unlimited mileage and I stand behind my work and my word. I am proud of what I do and hopefully that guy you are dealing with is the same way. There are a few of us that do work this way and lots that don't. I got my fingers crossed he will help you out good and be a stand up man. 
Plus, if that company uses TransStar converters, they put the GM codes on the converters and it would be easy to tell if it is correct. Dacco does the same, as ATCS. I don't use Dacco anymore due to some vibration problems they had and have had EXCELLENT luck with ATCS for the last couple years.
Just brought the truck back home from the tranny shop...they had called me at work and said that they had originally sold this transmission as a carry-out item and had not installed it in the truck themselves, therefore I would be responsible for all the labor for pulling it out of the truck and reinstalling it when finished. I told them not to touch it, and to lock the key in the truck and I'd be by to pick it up later. I think I'd rather just put the valve body in and change the fluid/filter, and hope for the best until I get the money together and buy a rebuilt transmission. Better to spend the money on a transmission (from a different shop or individual builder) and change it out myself than spend the money on these clowns to do the work, especially if they don't know or are denying that they know what the actual problem with it is...
