Fresh rebuilt 4l60e popping p1870 code
 

Have a fresh rebuilt 4l60e and a brand new 3600 stall behind a cammed lq9 in a 2000 formula. I've got about 75 miles on it and the torque converter has locked up before but on a drive today it didn't lock up. When I got home I put it on the reader it read p1870 and no other codes. I also checked the fluid and it is a little over full. I've read bad valve body and such but it just rebuilt, any other possible causes? Need a tune? Check electrical connections? I'm at a loss, really hoping its not the valve body

What repairs/modifications to the valve body were done during the rebuild? It should have been completely disassembled and modifications made.

A "cheapo" rebuild might barely touch the valve body (VB). A leaking TCC valve will cause the 1870 code because the lockup clutch is slipping (bad!). An "OEM" fix require a $50 part from Sonnax, a $150 reamer and time and experience to fix it. Ask the builder if this was done.

Most aftermarket converters work better with an on/off TCC valve instead of the troublesome/leaky PWM factory OEM one. Therefore the solution is to install an inexpensive $12 TCC valve that simply works on/off and doesn't leak. You stall converter will also last longer. You will feel the lockup engage, but I suspect anyone reading this forum would prefer that anyway.

It does require dropping the VB, but a trans shop should be able to do that and install the valve with about 1H of labor.

Techpak makes a $15 "1870 fixer" part available from ebay and other (cheaper) sources:

For 4L60E up through 2000:

http://hptransparts.com/techpak-fitz...0-a74741q.html

For 4l60E 2001+:

http://hptransparts.com/techpak-fitz...0-a74741q.html

http://www.transmissionpartsusa.com/...-0a74741qa.htm

Note that the Transgo HD2 shift kit comes with its own TCC on/off valve, as does the Sonnax Performance Pack shift kit.

This thread might interest you too:
https://ls1tech.com/forums/automatic...ift-issue.html

Thanks for all the info. Gonna call the shop and get some more info today and get this problem resolved

since you have a 2000.......you may or may not have the revised TCC valve line up......it was changed in 2001 but my 2000 had it........the new valve is supposed to reduce wear in the TCC bore

it is easy to check the TCC to look for wear and maybe a broken spring

Thought I would add to this thread unless a mod thinks it should be its own entity.

I am having the same issue. I just rebuilt the 4L60E for a 2003 2WD trailblazer because pump rotor had cracked. Having said that, I replace the pump with a reman from WIT, while I had it out I went ahead and had trans shop install the sonnax valve in the TCC bore. So..... IT has a 'fresh' stator shaft, 'fresh' valves in pump and the sonnax valve that is supposed to fix this code.

The CEL came on last. Drove about 40 minutes away on highway to dinner and ate. Car sat for maybe 2 hours. about 10 minutes into the drive home, the CEL pops on. Get home and its the P1870. Really at a loss of what to do now.

I wondering when it runs self checks for this code, maybe on my short trips (5miles) home to work and to lunch it doesn't throw a code because its not long enough drive to get it to act up. I am not even sure when TCC lock up is supposed to happen. I probably wouldn't care if it was just off or on. I just don't want to ruin the brand new GM torque converter. This is the second one I put in.

Code 1870 indicates the PCM is detecting too much slippage when the converter is supposed to be locked. It does this by comparing engine RPM with VSS speed and knowing the trans gear ratios. While the converter won't lock until the engine/trans are warmed up, that should occur in less than 10 minutes or 5 miles.
With so many new parts, it could be a defective TCC valve rebuild, a defective converter, a leak somewhere in the pump or a mis-assembly.
Did you replace the o-ring on the input shaft before you installed the new converter?
Please confirm that the pump is from a '98 thru '05 donor, and not e.g. a '95.
Perhaps one of the pros knows how to isolate the problem better.

PWM is cast into the pump. I did half ass it and reuse the input shaft oring for the torque converter. When I took it out the second time to fix my mistake on the valve body. I drove plenty far Sunday to give the vehicle a good shake down.

Ill see if I can get a guy at work to ride with me with a Tech 2 and check out live data with slip speed. Reading a little more here, Im wondering if light throttle and cruising speed may play a part with low line pressure and letting it slip. I was thinking to put in a sonnax boost valve. Try some easy cheap stuff. That's not fixing the root cause I know.

I probably should have dropped the $ to get a GM reman. But I like working on things my own and learning. Problem is attaining experience.

I saw the trouble shooting method of a checkball in a valve or port, but I need to research that and I think it should help narrow down areas of issues. I could just spend about 350 in a reman VB and harness with TCC solenoid, but that's throwing parts at it without diagnosis. So, I have a direction to go and I'll let you guys know.

What Sonnax valve to fix P1870?

Did you bust the TCC Enable Solenoid pulling the pump?

I don't have trouble out of 4L60E locking up with a Trans Go TCC Regulator Valve, New harness, & New solenoids.

I have seen the TCC Apply Valve Springs in the pump break, Lodge in the pump not allowing the valve to stroke.....Rare occurrence & I have only seen it on pumps that uses double springs.

A Checkball in the TCC Enable Solenoid snout will eliminate the enable solenoid as a cause. Just a check....It will set a "TCC solenoid stuck on" code if left that way.

Not saying a sonnax valve to fix P1870 exactly, but to boost line pressure at light or cruise throttle. If I remember right, it (cel) came on entering a bridge ramp that crosses over that same highway. Not sure if that one bridge caused the excess slippage 3 times in a row. I need to do more reading. But I did read a post on here about line pressure being around 55 at light throttle or cruising speeds.

Upon the reinstall of the harness 2nd go around, the snout was a bit finnicky going in, so I jammed some blue trans gel around the oring and popped it in. I do recall it may have taken more force to go in this time. I was in a bit of a hurry, I had to get off the bench so a flatrate guy could tear down a 6L80.

Its confusing me because its not a consistent CEL. (Actually first time it came on was a few minutes into driving home on highway after driving 40 minutes out to dinner) I had a beer so I was taking it easy, driving around 70 mph or 75 mph. No light today driving to work or doing errands at lunch. Bank, food, then getting gas.

Which is why Im thinking if I boost line pressure I 'may' fix the issue for me. But If I drop the pan, Im doing the harness, boost valve and PWM solenoid, TCC solenoid. Those are all still original.

Thanks for the input and insight. I pulled all the VB and pan side apart before going down the case. I could have knicked something important, I popped the pump out just like Hiram from Automatic Transmissions. Again, me lacking experience could be an issue here.

P1870 is a "sanity" check code, The set/trip criteria varies per calibration. Basically.....The PCM is commanding a high enough PWM duty cycle for the TCC to not slip more than 150 rpm.

You will kill a clutch (3-4's) long before line pressure will affect TCC engagement at steady state cruising.

What do you mean as in 'sanity' check code? You could still have an issue but it may take 50-100 miles to set?

I would rather not take it back out again to replace burnt clutches, I may just go ahead and replace those internal electronics, solenoids and harness. I may as well do the 3-2 shift and it will almost be a new valve body.

Mac

Cllinebarger is just saying that even very low line pressure is enough to keep the TCC locked. So installing a bigger Sonnax boost valve is not going to help your TCC issue. (Although I always think its a good idea.)

Just replacing all the solenoids is not going to give you "almost a new valve body" because the problem could be in the TCC valve area.
I've have bought very good valve bodies from ebay seller "powertrainpartsplus" and upon my recommendation other members here have been happy with them too. I see a 2003 valve body on their site right now for $67.70 listed as "Excellent Condition". If you don't mind a firmer TCC apply, you could add a Fitzall TCC valve to that which would almost guarantee fixing your 1870 code problem. (I don't think the Fitzall valve fits after the VB is reamed for the Sonnax valve.)

Sure, that'll work.
There was just a thread on here where someone was tuning more and more pressure into it, until it stopped moving.

Want to hear something funny? :huh:

Tear the transmission down right now and go over everything, FIND THE PROBLEM. This will take less time than doing it the way you're doing it.

:cheers: thank you all for such advice. I may drive around and see when it pops back on. But I know if it happened once, it will probably happen again. Just need to get through the holidays before I blow more money. At least the fluid is 'free' at work. There is enough floating around with the mechanics to refill pan a few times. I will probably try a harness first and the boost valve, then a used VB if possible. Hate the fact that I spent $ on the sonnax valve to prepare for and eliminate a possible P1870 since I had no history on the trans, but if a new VB will fix it, that's what I will do.

The Fitzall TCC valve will most likely fix you problem. As for the Sonnax boost valve it goes in the pump. If you bought it installing it won't hurt anything and will firm up shifts..

https://ls1tech.com/forums/automatic...2-18-17-a.html

I guess I could tear it down a 3rd time, but It would be easier to do a few $30 things and see what happens. it took 5 days for the cel to come on the first time. cleared it out, and two days later, still no code coming on, I am not sure what damage could be happening by continuing to drive it. While I'm at work I am just forking around on the keyboard and learning what I can about a 4L60E and what my issues are. I work in parts at a GM dealer so, I have some good resources, but the techs are mostly replacers, because it doesn't pay well to overhaul a trans VS getting a GM 3YR/100K warranty one for less than labor to over haul and parts to rebuild with only a 1 YR warranty.

No book or internet information is going to tell you whats wrong with your transmission. You're going to learn more "what if's" reading about what could be wrong vs hands on "what is wrong".
There's always option #2, throw parts at it til it burns down and then throw it all away and get a reman.

The PCM uses Engine RPM & VSS Output to calculate TCC Slip RPM, The code set criteria could be 2 or 3 trips (on-off key cycles) to set a P1870.

Correct me if I am wrong, but once the Sonnax oversize TCC valve is installed, which involves first reaming the VB bore for that oversize valve, the Fitzall can no longer be used.
Hence I recommended getting a used VB and since the stock TCC valve might be worn in that, install the Fitzall into the replacement VB.