P1870 Code... Need Some Insight

[3pt1lumina]

On my 1997 Lumina LS with 157k, for the past 10 months or so, I'd get this code. In that time, I've seen the light 4 times or so. It will go on, and then I will clear it and it will stay gone for awhile.

 

Now, since last July I've noticed on long trips, the TCC doesn't want to engage. Sometimes I downshift the car manually, then when it upshifts it will engage. Sometimes it work properly. Sometimes it wont engage at all. But this never throws the light. The SES light comes on when the car is operating properly.

 

So a couple of questions here:

 

A. What is happening? Is this the TCC not engaging?

B. To have it fixed or not? This is a car I need to be reliable for me every day.

C. The last time I have record of the tranny fluid being changed was 44k, it now has 157k; if I replace this fluid am I looking for a lot of problems in the future? The fluid is clean and does not smell burnt.

D. What is this going to cost me? The tranny guy at work wants no part in fixing the car.

 

BTW, it's a 3100 with a 4T60E in it.

 

Thanks!

[1990lumina]

When I search that code the definition comes up as: "Transaxle Component Slipping".

 

Sounds like you have a slipping transmission that isn't related to the TCC at all. New fluid might help but it sounds like the damage is already done.

[jman093]

I'm fighting this exact problem on both my GTP and my sister's Z34 at the moment. I talked the tranny guy at my dealership's Chevy store and he thought it might be TCC slippage. He told me to check it on the tech 2 when the vehicle was acting up and normal slippage should be 20-60 rpm with clutch engaged. I checked it on my GTP and it was so only in the 20s and 30s. Haven't checked on the Z34. So I don't know. I'm thinking I might take it in and just let him diagnose the GTP. He's one of the best trans guys around. You must work at a shop so you might borrow the scanner and check TCC slippage too w/ clutch engaged.

 

And I would absolutely change the fluid and filter. There's no reason not to. The GTP started doing this late last summer and I changed the fluid and filter because it was something I wanted to do anyways and the problem went away for several months. I figured I'd gotten rid of it completely, but it's now back. But if your fluid really hasn't been changed for over 100k miles, it may indeed cure your car. Plus you might put in Dexron VI fluid in it when you change it.

[5speedz34]

Can you explain how TCC slippage works?

[mfewtrail]

It could be TCC slippage due to a worn valve body bore. Do a google search for that code # and or that code # + 4T60E and you'll find a lot of info on it.

 

Here's an example of scanning the car for TCC slippage vs. duty cycle to see if the TCC is actually slipping.

http://www.specialtytrans.com/specialty/gm/4T60E/4t60e_tcc_slip_diagnosis.htm

[Crazy K]

Can you explain how TCC slippage works?

later vehicles are supposed to have a little TCC slip, and have a different clutch material for the TCC that allows for it. I think this change was made in 97 or 96, I found this out when researching torque converter stall speed.

 

in my 95, something is wrong and the TCC stops holding when the transmission is too hot. A transmission cooler has made the vehicle operable for the time being, and as I have said to several times... the 4t60e should have an auxiliary transmission cooler added...

[jman093]

And the TCC solenoid is duty cycle controlled. If you start giving it gas (but not so much that it releases the clutch, the increase in torque will cause the clutch to slip more and the controller steps up the duty cycle to bring it back down.