Trans Code P1870??? Why??

[94GPGTP]

I have a newer rebuilt trans in my car from a 95 monte z34 in my 96 GPSE 3100... I have not had a problem with it until the last 5 miles.. the SES Light came on.. I used my brothers scanner and scaned it and the 1870 code came up... I just cleared the code and havent driven the car yet... I looked in the chilton's book and it states Transaxle component slippage.. What is slipping and why?? there is no problem that i can tell with the trans.. it has 23,000 on a rebuild in terre haute,in tranny shop...

[94GPGTP]

well i just went for a test drive and crusing it doesnt turn on.. but giving it about WOT the light will turn on.. i cleared the SES light again and i will find out later what happens..

[3400-95-Modified]

is the gear ratio of the trans different than your original. i got that code when I went from a 2.97 to a 3.33 since the drive sprocket ratio changed from .89:1 to 1:1

I had to change the drive sprocket ratio setting in my ecm to reflect which trans I had.

BUT mine only did this at cruse on the highway... so your issue may be different...

[94GPGTP]

i would say so.. i know that the gaer ratios inside the trans is different between the 3.4 DOHC and the 3100.. its all 3.4DOHC insides..

Could i change the FDR? i have a spare that is i think out of a 3100 grand prix....

[3400-95-Modified]

You could possibly put in a 3.06 diff and get it close to a stock 2.97 if thats what it was, but I think it will still throw a code.

[94GPGTP]

would you know if anything is in harm? or is something wrong when the code pops up? There is nothing wrong when it turns on that i can tell...
What would have to be changed to fix this problem?

[3400-95-Modified]

I know on mine with that code thrown it shut off TCC lockup, so gas mileage would suffer... you would just need to change the table in your ecm to reflect your trans change, which would be the drive sprocket ratio table.

OR shut that code off, that worked for mine when I couldnt change that table... Do you have DHP or similar?

[94GPGTP]

my tcc does work...

no i dont have a dhp.. a tuner correct... i dont have one.. that kinda sucks

[IsaacHayes]

I believe 96 W body 3100 gear ratio is higher than 2.97. When I drove one I know it was higher than my car. Unless it was an option on the 3100's in 96 to have shorter gears like the DOHC ???

3.06 compared to my 2.97 I don't know if I would be able to tell that much, but when I drove one I noticed.

[3400-95-Modified]

Can you get the tag numbers off the back of the transmissions? I can tell you exactly whats in them if you do along with the gear ratio.

And what i meant by changing to 3.06 was if there is a 3.33 in there and its a 1:1 drive ratio then you would only have the optio of going to a 3.06 diff to get it close to the stock 2.97 if thats what it was, only other way to get there would be leave the 3.33 in place and change the drive and driven gears which is much more work.

[94GPGTP]

ill get you a tag number off the trans that was in the car and the one in the car now..