Question regarding monitoring a 4L60E with a GM Tech scanner

Drec

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On another thread I mentioned having the transmission rebuilt in my Envoy. The shop asked me to bring it back to check, before we go on a trip, trans fluid and some other checks. So this morning I drove it to the shop. On the way there, I noticed a "Service Light" had set, so I mention it to the shop. They put a scanner on it and it was a transmission code that reviled the torque converter was not fully locking up. So I'm going to take it back tomorrow. Anyway on the way home, I noticed that it has a hard shift between 1 & 2, with the others all being normal.

My question is, can I set up my Tech 2 clone to monitor the shifting and how would I tell what is normal? Anything else I should I look at?
 

Reprise

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Subscribing, as I'm an utter novice using my recently acquired Tech 2.
Mine shifts (very) firmly 1-2, but I run the Vette servo and drilled the separator plate to .093 (so I kinda got what I asked for)
 
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Drec

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I've only put about 150 miles on this trans since the build. It just started shifting like this today, a hard shift between 1 & 2. On some of my other cars, if I was on it, it would squeal the tires between shifts 1 & 2.

I'm a novice with the Tech 2 as well. I was going to hook it up tomorrow for the trip to the transmission shop.
 

Sparky

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Huh, that kind of behavior on an older transmission wouldn't surprise me as that's not an overly uncommon issue with the 4L60E, but I would not expect a new/rebuilt transmission to do that.
 

Mooseman

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Sounds like a bad solenoid or connection at the connector for two things to act weird. Or a ground.

I haven't played with it for the tranny except to make it shift and engage the TCC manually when it wouldn't on its own. Turned out to be a speedo sensor issue. I believe there is a whole section just on tranny data.
 

Drec

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I drove it tonight and it shifted beautifully. The shop owner wants me to bring it back in; which I'll do tomorrow morning. As far as the code goes, he was thinking a sticking solenoid; which wasn't fully engaging the lockup converter. Like I said before, it shifted beautifully tonight, no hard shifts.
 

Sparky

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I know when the TCC valve bore is worn it can behave normally until it is hot, then it starts losing ability to lock the converter, which results in more heat, and the transmission starts doing weird things like slamming the 1-2 shift. If the code was P1870 a neck-jarring 1-2 shift is a common symptom that occurs with it (been there done that).

But like I said I wouldn't think a rebuilt transmission should have a worn bore as it should have been fixed during the rebuild. But then, some things can get overlooked...
 
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Reprise

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But then, some things can get overlooked...

True that - but one would hope the TCC valve / bore wouldn't be one of them, since it's one of the main weak points of the 4L60e (hey, if we all know about it, and most of us are 'shadetrees'... ) :frown:
:deadhorse:
 

Sparky

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You know how many times I've run into cases where we shadetree guys know more than "trained" people at shops...
 

Reprise

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You know how many times I've run into cases where we shadetree guys know more than "trained" people at shops...

Agreed! I've run into that, myself.

I'll grant you that transmission overhaul / repair is beyond the scope of many (if not most) 'general repair' garages - those who accept the work almost certainly farm it out to their contacts who are specialists. But in the case of the person / facility actually *doing* the work - it's not like the 4L60e is some exotic new whiz-bang (no pun intended) slushbox.

The basic concept / design goes all the way back to the TH350 - which I had in a '70 Monte Carlo, for cryin' out loud (and it had a factory drain plug, believe it or not... ::laughing:: ) Thing ran strong, too. But those units were overbuilt, before CAD came along and told the engineers / accountants what / where to remove costs & materials to make it last 'just long enough' for their customers, relative to usage / conditions.

In fact, as I think of it...of all of us kids running around with leftover '60s-'70s GM cars back in the early '80s - almost all of them had a Turbo 350 (except for one kid whose parents passed him down a Vega - a 2-door wagon - in yellow, no less. But at least he could fit his entire Gretsch double kick drum kit into it, cymbals, hardware & all (sorta like Neil Peart with his Pinto when he auditioned for Alex & Geddy, I suppose?))

I owned only one car with a TH400 - a '73 Chevelle Laguna (with swivel buckets!) that originally had a 454 (by the time I got it, that was long gone, and a 350 in its place (5.7L, for you young'ins). ALL of us, being young, dumb and...(oops...family website!) ran the hell out of those cars, and very few of us had any trans issues, much less outright failures. But I digress (as usual...lol).

Back on topic - there's only 3-4 areas of the 4L60e regarded as 'weak', and needing to be addressed. One of them (and I'd posit the one that happens *most* often, with accumulated mileage) is the TCC valve wearing in its bore. After all, TransGo made a special kit to deal specifically with this, right?

IMO, it's inexcusable that a shop / builder / reman would charge $2900 (-? IIRC) and not address that in some fashion.

I'd even allow them a new stock VB / TCC valve (because, to be honest, who is going to drive their rebuild *another* 150-200K miles before something else happens to the vehicle to take it out of that owner's hands?) But that would be the *minimum* allowable fix, as long as they didn't represent they did something different, like an oversized Sonnax valve / boring job, where they could claim 'labor' costs - and even then, the cost of the reamer tool was paid for on the prior job(s).

PS: I know you already know all of this (as do most of the 'hardcore' owners on this board, not that I'm hardcore.) So I'm not arguing with you. Just expressing my frustration at people who would charge a lot of money for bad / negligent / shoddy / wrong / missing work. Yes, I know, the world isn't a perfect place, and sh!t happens - we all have to deal with it. So don't call me 'Pollyanna'...lol.

And to @Drec - I'm *not* suggesting your builder did any of those things - we're just discussing 'what if' scenarios, if you will.

I wish I knew a bit more about fluid dynamics - I could probably make a nice side income as an A/T rebuilder (specializing in GMs...all other mfg trannys are (even worse) crap...ROFLMAO) I could even see myself actually 'enjoying' doing it (till the 1st one came back...LMAO)
 

Drec

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I took the Envoy back to the shop this morning, by their invitation yesterday. They asked me last Friday to bring it back this week so they could check the fluid and see if any problems (leaks or anything else) might have popped up. On the way down there yesterday for the check, the infamous 1870 code popped up. So they did their check, cleared the code and then did a drive test. When he returned, he asked me to bring it back so they could tear into it again to figure out what might have happened; which is where we are now.

When I started this thread, my idea was to get some insight into the Tech 2, while driving it back down to the shop. I plugged in in this morning and had a look, but should have taken more time; which I didn't have.

Anyway, the shop that is doing the work was highly recommended by some of my car friends that is a family local owned business; which opened in the early 1970's. That's all they do is transmissions.

When I picked up the Envoy last Friday, it worked great, until I'd put about 150 miles on. Then the 1870 issue started popping up. It came up on the trip yesterday to the shop, it was cleared yesterday and worked great for another 100 miles and then came back.
 
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Sparky

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Yep, that's pretty typical of P1870. When things are cooled off, it'll work fine, but warm it up good and it starts to act up, and then *blink* the light is on and it starts doing weird shifts.

At least you're getting the code right away. When my one 4L60E was having trouble in my old car years ago, I was fighting the converter not locking or staying locked with RPM flutter for over a year and killing my highway mpg before I even got a single instance of P1870 and a head-banging 1-2. Drove me nuts, so many people had no idea what the issue was aside from "your trans may be dying dude." Actually bought the Transgo kit on a whim before I even got the P1870 that one time. Installed it and that trans has been perfect since then. Made a believer out of me with that kit... Heck, I still have that trans, long story short it ended up in my current Camaro :laugh: it has over 170k on it now, lives behind a cammed 3.8L that has shattered a few rear axles, and so far hasn't skipped a beat yet!
 

Drec

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.......................When my one 4L60E was having trouble in my old car years ago, I was fighting the converter not locking or staying locked with RPM flutter ..............................
That is exactly what my trans was doing before. Then it threw the 1870 code and everything went downhill from there. I got a call a couple of hours ago telling me that my Envoy is done. I'll find out tomorrow what they fixed and after I drive it a little, I'll know for sure if it is fixed.
 

Reprise

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Do I owe @Sparky a (figurative) apology? :undecided: Looks like he might have been right on this one, after all - ?
 

Sparky

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Tsk tsk they shouldn't have overlooked it, but at least they made it right. *edit* was that before or after they took a second look at it?
 

Drec

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The itemized bill that they gave me was for when they initially worked on it, that included the Transgo Valve Body Kit. After dropping it off yesterday, they changed out some solenoids. Just received a call a few minutes ago, they don't like the way it is still shifting and are pulling the valve body again.
 

Sparky

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So something is up with the body and/or kit install.
 

Drec

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That's where they are at now, valve body or kit install. They are supposed to call me back in the next few hours, if it will be ready after they drive test it. The shop has been great, calling me to keep me in the loop on what is going on.
 

Drec

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I picked up the Envoy late this afternoon. The shop changed out the valve body and put the shift kit in it. They said there was a shuck valve in the old one that they couldn't free up. On the way home, the drive is about 40 miles, it worked great. Then I had to stop and it shifted hard from 1-2. When this happened, I hooked up my ODB2 scanner and it had a pending 1870 code. So I called and talked to the shop. I suggested that I drive it for a while and see if it gets better. The shop suggested that if after a week, if there is still a problem that I'd bring it back, they would pull it back out and go though it again. I made a stop for a couple of minutes and it work great the rest of the way home.
 
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Mooseman

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Hoping it holds. Might give you the time to hook up the Tech 2 and check to see what data can be monitored.
 

Drec

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Today I drove it to a swap meet about 50 miles north of me. By the time I got there, there was a hard 1870 code thrown. When (I would imagine), it has sat and/or somewhat cold, the transmission shifts (1-2) normally. The other gears seem to shift normally as well, all of the time. When it has been warm, it has a hard shift between 1-2.
 

Reprise

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Sorry to hear you're still having issues. At this point, you know the 'usual suspect' has been addressed and rechecked.
It may be time to start looking at secondary causes.
You mentioned that you have a detailed invoice - can you post (or scan) what was done in addition to the VB work?

Also, if it doesn't already have an external cooler - I'd give serious thought to adding one (a stacked plate over a tube / fin, as they're the most efficient).
We know the issue happens when the fluid gets hot - if you can keep it even 20F cooler, you may lessen or (even eliminate) it.
Conventional wisdom says that the heat leads to slippage, and slippage causes the trans to boost to max line pressure to compensate - hence, the hard 1-2.
 

Drec

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I mentioned adding a cooler to the shop owner, but he didn't think that would be the problem, but thought that it would be a good addition. I was thinking about disconnecting the battery to refresh the whole system that might have an errant bit or two set. I'll post the list of parts that when into it later today.
 

Mooseman

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I agree with the shop. The cooler helps with longevity. It's having issues when it's fully warmed up. You could with the Tech 2 monitor the temps and report to the shop when it starts to hard shift.
 
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Drec

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I noticed that there were a couple of other codes set; which led me to think that maybe the battery wasn't disconnected when they worked on the transmission, but maybe they were and reset. There was a speed sensor and a data transmission error, with the latter possibly being a problem. My wife and are going to be gone for a few days, so I'll read up on Tech2 diagnostics. I suppose the GM Service Manuals would have procedures for checking this stuff.
 

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