chevy1120

iTrader: (2)

i have a 2002 avalanche 1500 4x4 has the 4l60e trans i was driving and it started shifting hard and making a thud sound when it shifted and the check engine light came on had it scanned and it came up with this code "P1870 Transmission Component Slipping" would anyone know what it is? thanks for any help

chevy1120

iTrader: (2)

also it mostly doing it once iv been driving for a bit idk if that helps any

mantycarguy

Most likely a worn tcc valve in valve body. Usually the valve is loose in the bore and as the fluid warms up pressure drops enough to cause this problem to be more evident. Do a search for code P1870 and you will find a number of solutions from aftermarket trans parts suppliers.

mrvedit

^^^ Exactly correct. The 1870 code means the converter's lockup clutch (TCC) is slipping. When that happens the computer increases line pressure which then gives you the hard shifts.

A good shop can rebuild the valve body for you; the trans does not need to be removed. Probably close to $400 with a fluid and filter change. Or the shop might choose to install a rebuilt valve body. Since the valve body needs to be reamed out (with a $150 tool) and a special over-sized TCC valve installed, it is not a job for a newbie.
However, if you are OK with firmer TCC engagement, you can switch to a simpler on/off TCC valve, which only cost $15 and isn't overly complex to install. You do need to drop the valve body.

Let us know which direction you are leaning toward.

chevy1120

iTrader: (2)

how much firmer would it be? and would that affect the trans at all?

carlsonauto

Not a lot firmer it basically turns it into an older stlye tcc lockup that is on or off. What you have now slips the tcc intentionally instead of locking it completely all of the time that its engaged. If you put the on/off style valve in it will feel similar to a shift, nothing harsh or crazy. There are really no adverse effects that I have seen using that style valve and I have used a lot of them.

chevy1120

iTrader: (2)

would you happen to know where i could get the stock valve cheap even a reman would be okay

chevy1120

iTrader: (2)

or the part number i found some on ebay but just want to make sure i have the right one

mrvedit

Not sure what you mean by "stock valve". Do you mean a Valve body (VB) or the stock TCC valve? The stock TCC valve will not fit - the VB is too worn. Sonnax makes the oversize TCC valve ($50 ?), but you need the $150 reaming tool and probably some experience doing this.

A remanufactured VB from ebay is a reasonable choice. Don't go cheap - good ones are in the $150 to $195 range. I'm not aware of any VB changes between '96 and '06, so anything in those years should be fine, newer is probably better.

chevy1120

iTrader: (2)

okay so i took it to a shop they hooked it up to the computer drove it around then turn the check engine light off and they say everything is fine its shifting okay and the light isnt coming back on. when the issue happened i was towing a car got to a hill and she was having a little trouble getting up so i turned the over drive off then back on once i got back up and then i started having shift issues i dont know if this could happen but my thoughts are could it have thought it was slipping cause i took it in and out of o/d and once the computer was reading that that made the trans shift hard?

RedRocketZ28

iTrader: (19)

Just for future reference, when towing something of that weight, leave it in 3rd. Overdrive should never be used when towing something like that.

Hope everything is okay with it.

mrvedit

Yes, as I said before: With a 1870 code the computer increases line pressure which then gives you the hard shifts.

Glad its all fixed. The heavy towing info would have been a clue it was a temporary glitch.
Thanks the towing info RedRocketZ28; that was new to me.