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**Dan Vincent** · 08-03-2004, 12:54 AM

That's a symptom of the worn TCC valve in your tranny... get a scantool and look at the numbers for TCC duty cycle and slip RPM. Any experienced tranny shop should know how to diagnose, get ready to open up your wallet for $300 in a rebore.

**99W68Firebird** · 08-03-2004, 01:12 AM

same thing he said. try to find a Trans shop around named Aamco.. thats who Dan recommended me too because every other place sounded clueless to what was going on and when i went to Aamco the guy knew and he didnt even look at it. But im still trying to save up to get it fixed.

**Need4Camaro** · 08-03-2004, 04:43 PM

I just have to ask, Whats a TCC Valve and whats it do?... howcome these symptoms come everyonce in awhile and are not constant? like all day today my car drove plain perfect even when I got on it...

**99W68Firebird** · 08-03-2004, 05:17 PM

transmissionspecialty.com/parts/PDF/77754-03k-04k(rb).pdf

add www. to beginning of that link and copy and paste it into URL it wouldnt let me post it as a link here.

this should answer all your questions

**Dan Vincent** · 08-03-2004, 09:06 PM

Originally posted by Need4Camaro:
I just have to ask, Whats a TCC Valve and whats it do?... howcome these symptoms come everyonce in awhile and are not constant? like all day today my car drove plain perfect even when I got on it...

The harsh 1-2 shift is a result of the PCM jacking up the line pressure to full after a P1870 code is set... that code normally means "Transmission component slipping," but that's pretty vague, isn't it?

That code is set by the torque converter's slip RPM. If the torque converter clutch is signaled to be on, there should be 50 RPM or less of slip in the torque converter (this can be looked at with a scantool). If the PCM detects 150 RPM or more of slip in the converter with the clutch engaged, it will set the P1870 and will jack up the line pressure, causing the harsh shifts. The PCM thinks the tranny is about to grenade (which is completely false, well, at least in this case) and jacks up the line pressure to help you get home. Sometimes it doesn't set the P1870 (there's certain conditions that make the code, and subsequently the SES light), which is why you might not get the harsh shifting all the time.

Since the design of the valve makes it wear out prematurely, signal oil exhausts right past the valve, causing no-lockup. You might still get lockup, but it generally takes 30-45 minutes of 30 MPH+ driving for the oil to heat up and thin out.

If you don't get this fixed, you won't necessarily blow up your tranny, but you will waste gasoline and torch your tranny oil much faster, since no lockup means your tranny oil will get over 220 degrees hot. Torched tranny oil WILL blue your converter and burn up your clutches.

The reason I suggest this so often is that the 4L60E is actually a pretty good tranny - aside from its weak 3-4 clutch band, it's pretty hard to grenade it most of the time (although I highly reccomend installing even a mild shift kit and a corvette servo, these are mandatory upgrades for any automatic). This is a problem common with all rear-drive GMs with the 4L60E made from 95-00 - the guy at the tranny shop who did it for me says he does one every week or so. This is bread and butter work for tranny shops, so if you tell him you have a rear-drive GM with the 4L60E and a P1870 he should be pretty familiar already.

Look out for the following:

TCC ENGAGE: This is the PCM signal commanding the clutch to engage. It will be "ON" when the PCM commands it on regardless of the clutch's actual engagement status.

TC RPM: How many RPMs your converter is spinning. When the converter clutch is unlocked, it will spin at the same RPM as the crank. When the clutch is locked, it should read generally between 0-50 RPM. GM Changed their slip methodology with the 4L60E - it was meant to give a "soft" apply, and introduced a limited amount of slip - generally under 50 RPM - as opposed to the old 700R4/4L60 method of trying to eliminate all slip. If the slip changes frequently and reads over 50 RPM for long periods of time, your clutch ain't locking up.

TCC DUTY CYCLE: This is the duty cycle of the Pulse width modulated valve. It should usually be somewhere around 40-50%. If it's unusually high (it'll generally be around 90% on a bad valve), this means the PCM is trying to force the TCC to engage, but the clutch is not engaging.

Knowing these parameters, if you have high RPM numbers and high duty cycle wihle the PCM says the clutch is engaged, your valve is toast. If your car is still under warranty (which they're not), you could take it back to the dealer for the 2000+ SER valve body. The most common method of fixing this is the sonnax kit listed earlier in this thread - it'll cost about $300 since you have to pay for the kit, tranny oil, filter, gasket, and a portion of the cost of the reamer, as well as labor.

This would be a great time to have the shop install a shift kit and corvette servo, btw.

Before you spend any money on anything, find someone with a scantool you can borrow and pull any history codes you may have, and use the history mode to check out the car while you drive.

**Need4Camaro** · 08-04-2004, 03:08 PM

[quote]Originally posted by Dan Vincent:

Originally posted by Need4Camaro:
I just have to ask, Whats a TCC Valve and whats it do?... howcome these symptoms come everyonce in awhile and are not constant? like all day today my car drove plain perfect even when I got on it...

The harsh 1-2 shift is a result of the PCM jacking up the line pressure to full after a P1870 code is set... that code normally means "Transmission component slipping," but that's pretty vague, isn't it?

That code is set by the torque converter's slip RPM. If the torque converter clutch is signaled to be on, there should be 50 RPM or less of slip in the torque converter (this can be looked at with a scantool). If the PCM detects 150 RPM or more of slip in the converter with the clutch engaged, it will set the P1870 and will jack up the line pressure, causing the harsh shifts. The PCM thinks the tranny is about to grenade (which is completely false, well, at least in this case) and jacks up the line pressure to help you get home. Sometimes it doesn't set the P1870 (there's certain conditions that make the code, and subsequently the SES light), which is why you might not get the harsh shifting all the time.

Since the design of the valve makes it wear out prematurely, signal oil exhausts right past the valve, causing no-lockup. You might still get lockup, but it generally takes 30-45 minutes of 30 MPH+ driving for the oil to heat up and thin out.

If you don't get this fixed, you won't necessarily blow up your tranny, but you will waste gasoline and torch your tranny oil much faster, since no lockup means your tranny oil will get over 220 degrees hot. Torched tranny oil WILL blue your converter and burn up your clutches.

The reason I suggest this so often is that the 4L60E is actually a pretty good tranny - aside from its weak 3-4 clutch band, it's pretty hard to grenade it most of the time (although I highly reccomend installing even a mild shift kit and a corvette servo, these are mandatory upgrades for any automatic). This is a problem common with all rear-drive GMs with the 4L60E made from 95-00 - the guy at the tranny shop who did it for me says he does one every week or so. This is bread and butter work for tranny shops, so if you tell him you have a rear-drive GM with the 4L60E and a P1870 he should be pretty familiar already.

Look out for the following:

TCC ENGAGE: This is the PCM signal commanding the clutch to engage. It will be "ON" when the PCM commands it on regardless of the clutch's actual engagement status.

TC RPM: How many RPMs your converter is spinning. When the converter clutch is unlocked, it will spin at the same RPM as the crank. When the clutch is locked, it should read generally between 0-50 RPM. GM Changed their slip methodology with the 4L60E - it was meant to give a "soft" apply, and introduced a limited amount of slip - generally under 50 RPM - as opposed to the old 700R4/4L60 method of trying to eliminate all slip. If the slip changes frequently and reads over 50 RPM for long periods of time, your clutch ain't locking up.

TCC DUTY CYCLE: This is the duty cycle of the Pulse width modulated valve. It should usually be somewhere around 40-50%. If it's unusually high (it'll generally be around 90% on a bad valve), this means the PCM is trying to force the TCC to engage, but the clutch is not engaging.

Knowing these parameters, if you have high RPM numbers and high duty cycle wihle the PCM says the clutch is engaged, your valve is toast. If your car is still under warranty (which they're not), you could take it back to the dealer for the 2000+ SER valve body. The most common method of fixing this is the sonnax kit listed earlier in this thread - it'll cost about $300 since you have to pay for the kit, tranny oil, filter, gasket, and a portion of the cost of the reamer, as well as labor.

This would be a great time to have the shop install a shift kit and corvette servo, btw.

Before you spend any money on anything, find someone with a scantool you can borrow and pull any history codes you may have, and use the history mode to check out the car while you drive. [/QUOTE

I'm a bit lost...but basicly I need a new TCC valve to end the problem right?... Where can I get a shiftkit and corvette servo? BASICLY what you're saying is when the engine is engaging to the transmission (or letting off the clutch after throwing it in gear for 5 speeds)... It's slipping up and can't get a grip on it, causing the PCM to send more preasure to fix the problem, causing my rough shifting?

**Need4Camaro** · 08-04-2004, 06:51 PM

Okay... here's the deal... I got the code P1870. Aamco took a look at it and well... He said it would literally be cheaper for me to buy a new tranny than to fix this mess. So I'm going to do just that... What if I bought a Corvettes A4? would that fit?.. What kind of gears should I get since I'm in this mess anyway?... If I can't get a Vette tranny then I want to get a 5 speed... what would I have to change/labor to do this? Also what kind of gears should I get for this? Can I get the corvette part and shiftkit for a M5?... Also are there any other options as far as trannies go? thanks all

**Dan Vincent** · 08-04-2004, 07:02 PM

Originally posted by Need4Camaro:
Okay... here's the deal... I got the code P1870. Aamco took a look at it and well... He said it would literally be cheaper for me to buy a new tranny than to fix this mess. So I'm going to do just that... What if I bought a Corvettes A4? would that fit?.. What kind of gears should I get since I'm in this mess anyway?... If I can't get a Vette tranny then I want to get a 5 speed... what would I have to change/labor to do this? Also what kind of gears should I get for this? Can I get the corvette part and shiftkit for a M5?... Also are there any other options as far as trannies go? thanks all

Wait, I thought both of these cars had A4s? If one has an M5, don't bother, as the problem I was talking about is an A4 problem only. However, I'd like to be able to get a new or rebuilt 4L60E for only 300 bucks. It's a fix for a small problem and your tranny will probably give you more trouble free miles afterwards. Not all franchises are created equal, I guess. [img]smile.gif[/img]

You can buy the shift kit and servo from various places online... Tbyrne has the Transgo but not the servo... KDS has a package with teh kit and servo for slightly over $100. Not sure about labor, but any good tranny shop should be able to slap it in fairly quickly (IE book time).

http://store.kdsperformance.com/transhifkitw3.html

**Need4Camaro** · 08-04-2004, 07:13 PM

Originally posted by Dan Vincent:
</font><blockquote>quote:</font><hr />Originally posted by Need4Camaro:
Okay... here's the deal... I got the code P1870. Aamco took a look at it and well... He said it would literally be cheaper for me to buy a new tranny than to fix this mess. So I'm going to do just that... What if I bought a Corvettes A4? would that fit?.. What kind of gears should I get since I'm in this mess anyway?... If I can't get a Vette tranny then I want to get a 5 speed... what would I have to change/labor to do this? Also what kind of gears should I get for this? Can I get the corvette part and shiftkit for a M5?... Also are there any other options as far as trannies go? thanks all

Wait, I thought both of these cars had A4s? If one has an M5, don't bother, as the problem I was talking about is an A4 problem only. However, I'd like to be able to get a new or rebuilt 4L60E for only 300 bucks. It's a fix for a small problem and your tranny will probably give you more trouble free miles afterwards. Not all franchises are created equal, I guess. [img]smile.gif[/img]

You can buy the shift kit and servo from various places online... Tbyrne has the Transgo but not the servo... KDS has a package with teh kit and servo for slightly over $100. Not sure about labor, but any good tranny shop should be able to slap it in fairly quickly (IE book time).

http://store.kdsperformance.com/transhifkitw3.html </font>[/QUOTE]Teah, they're both A4's... I was just wondering if should switch to the M5 if I need to get a new tranny like Aamco is telling me... I'm not totally sure or posative so shoot me if I'm wrong but I believe I saw a post where someone said our tranny's cost less than $300... (thats very reassuring)... What did ya mean by "your tranny will probably give you more trouble free miles afterwards. Not all franchises are created equal" ???

Edit: By the way Dan, I checked out your car... We basicly got the same cars only your's is a bird and mine is a Camaro RS and we both got the Y87 from the same 97 year... Looking sweet bro... keep up the good work, but I think you shouldn't paint your interior... your seats really set it off enough, you don't want to OVERdo it... Heh we should get together sometime and get you some T-Tops...

[ August 04, 2004, 08:42 PM: Message edited by: Need4Camaro ]

**99W68Firebird** · 08-04-2004, 09:10 PM

what tranny are you going to get? if you get used tranny as same one you got, the same things gonna happen eventually, unless i think if you bought one from a 00-02' 4L60E cuz they fixed that problem.. someone plz correct me on that if im wrong.

**Dan Vincent** · 08-05-2004, 12:16 AM

but I think you shouldn't paint your interior... your seats really set it off enough, you don't want to OVERdo it... Heh we should get together sometime and get you some T-Tops...

The more I've been thinking about it, the more I've been disinclined to paint it. Considering the years of Armor-all and NXT I'll have to get off of it, lol... I'll take you up on the t-tops when I can get the cash :( Right now I don't have $600 to throw down on a t-top kit.

What did ya mean by "your tranny will probably give you more trouble free miles afterwards. Not all franchises are created equal" ???

I meant to get a second opinion. Not everyone's experiences may be equal, etc. Call around tranny shops in your area and tell them you've got the GM P1870 with the torque converter clutch valve wear and that you want the sonnax fix kit... they should know what you're talking about. It's an incredibly common problem with rear-drive cars, and aside from blowing the 3-4 bands (which doesn't happen too often, but it does) it's the biggest flaw in the early 4L60Es.

Transitioning to an M5 will be a painful, although rewarding process if you really want it that badly. Some of the people on the board have done it.

00-02' 4L60E cuz they fixed that problem.. someone plz correct me on that if im wrong.

No, you're right. They fixed it in mid-2000.

**Need4Camaro** · 08-05-2004, 06:20 PM

Okay, I'm not to experienced with tranny's and I don't have or know anyone around my area with a Scan tool so that idea is pretty useless for me... (not that I know how those tools work anyway)

So is this P1870 eventually due to happen on all GM cars pre-2000 with A4's? What exactly are the factors that lead up to it? like excessive accelleration? How do I know for sure that I didn't blow my 3-4 Bands and what are those anyway? Will the Sonnax fix prevent this from happening again in the future? If not then how can I?

**Dan Vincent** · 08-06-2004, 02:41 AM

3-4 bands are the clutch bands for shifting from third to fourth gear... the material they're made out of is rather weak, so extreme conditions can trash them.

The reason this code happens is because the hard aluminum valve vibrates extremely quickly (this is a pulse width modulated system, meaning it works on a pulsation rather than straight on off) against the soft aluminum valve body, wearing it out prematurely. Basically, it's a GM design flaw in the 95-00 4L60E valvebody... F-bodies, non-Z06 vettes, quarter-ton trucks, blazers, S10s, B-cars... and so on.

The sonnax kit has a new sleeve and valve that will solve it and prevent it from happening. After they rebore the valve body, the new sleeve and valve are inserted and you're good to go.

**OneManArmy** · 08-12-2004, 10:49 AM

woo I just got the famous p1870 code.... time to chunk out 500 bucks....

you know... **** GM....

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