P1870 code

[berettaboy]

So driving on the way home from bfest my service engine soon light came on. I got it checked out and it threw a p1870 code which I understand to mean the computer detected gear slippage. With my current leak its kinda tough to keep up on fluids but I didn't notice any slips yesterday like I have in the past when my fluids were low. When it slipped it'd never throw a code either. So can anyone give me some more details on this code?

Thanks in advance,
Kyle

[Chad91GTZ]

Does it shift into OD? What speed were you traveling? My guess is that you have a bad clutch hub. Probably the OD one. They burn up from time to time in the 4T-sleezys, especially if you've been low on fluid.

If it isn't shifting into 4th (OD) and that's when it pops the code, just keep it in D to avoid that 3-4 shift, especially in town.

[berettaboy]

Does it shift into OD? What speed were you traveling? My guess is that you have a bad clutch hub. Probably the OD one. They burn up from time to time in the 4T-sleezys, especially if you've been low on fluid.

If it isn't shifting into 4th (OD) and that's when it pops the code, just keep it in D to avoid that 3-4 shift, especially in town.

Hmm just to get this straight, I've always been a little confused on..
It goes...

P
R
N
OD
D
L

Is that correct? Or is it D then OD?

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[wi_corsica]

Yes, that's correct, but I do believe that D is actually an H.

[berettaboy]

Yes, that's correct, but I do believe that D is actually an H.

Its a D I was just confused which was OverDrive. I know D is the higher power of the two and I guess OverDrive is the more fuel efficient which I never understood the name but whatever. And as far as shifting Into 4th I don't notice a problem but I've always hard the common hard shift from 1st to 2nd.

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[Chad91GTZ]

Yes. OD, the one with the circle around the D, just includes fourth gear. I've only ever seen the computer throw that code twice. One was because the gearing inside the transmission was changed, at which point you disable that code so it doesn't pop up again. And the other is when the trans tries to shift but won't go into gear.

The reason I say bad clutch hub is because there are two shift solinoids. One does 1 -> 2 and 3 ->4 and the other one does 2->3.

So the fact that it shifts at all kinda rules those out. But you said it goes into 4th fine so I don't know.

Like I always say, auto trans only do three things, and they all start with s. Shift slip and crap. But they only do the second one for a short time before moving right into the 3rd.

[3X00-Modified]

Your partly right on how to fix that code chad Rather than disable it I just tell the ECU what gearing is in it after the change.

But yes anytime I've ever seen that code its been because I swapped gear ratios... I can only imagine on car that has nothing done to the trans at all then you probably have a clutch pack or something going out... The gear slip code also never gets thrown till it goes into TCC lockup from what I've experienced, so the other issue you could be having is a bad TCC in the torque converter and its not locking fully. The Engine can't do the math on the ratio till the converter is no longer slipping and the function of the converter is to slip.

Also Kyle, when you say D is the higher power of the two that's not really true... The only difference between the OD and D selector on the shifter is when the trans is in OD as Chad said it includes using 4th gear which is an over driven gear so yes giving you better fuel efficiency since the engine RPM's will drop. When it D your trans stops shifting at 3rd gear, a 1:1 ratio and when you let off the gas the engine is still engaged to the trans to help slow you down, using it sort of like a 5-speed car and engine braking... So really there is no power difference between the two at all, and that's a common misconception of many who don't understand what OD really means.

And Chad... mine Chirps and that doesn't start with an S

[berettaboy]

Yes. OD, the one with the circle around the D, just includes fourth gear. I've only ever seen the computer throw that code twice. One was because the gearing inside the transmission was changed, at which point you disable that code so it doesn't pop up again. And the other is when the trans tries to shift but won't go into gear.

The reason I say bad clutch hub is because there are two shift solinoids. One does 1 -> 2 and 3 ->4 and the other one does 2->3.

So the fact that it shifts at all kinda rules those out. But you said it goes into 4th fine so I don't know.

Like I always say, auto trans only do three things, and they all start with s. Shift slip and crap. But they only do the second one for a short time before moving right into the 3rd.

Your partly right on how to fix that code chad Rather than disable it I just tell the ECU what gearing is in it after the change.

But yes anytime I've ever seen that code its been because I swapped gear ratios... I can only imagine on car that has nothing done to the trans at all then you probably have a clutch pack or something going out... The gear slip code also never gets thrown till it goes into TCC lockup from what I've experienced, so the other issue you could be having is a bad TCC in the torque converter and its not locking fully. The Engine can't do the math on the ratio till the converter is no longer slipping and the function of the converter is to slip.

Also Kyle, when you say D is the higher power of the two that's not really true... The only difference between the OD and D selector on the shifter is when the trans is in OD as Chad said it includes using 4th gear which is an over driven gear so yes giving you better fuel efficiency since the engine RPM's will drop. When it D your trans stops shifting at 3rd gear, a 1:1 ratio and when you let off the gas the engine is still engaged to the trans to help slow you down, using it sort of like a 5-speed car and engine braking... So really there is no power difference between the two at all, and that's a common misconception of many who don't understand what OD really means.

And Chad... mine Chirps and that doesn't start with an S

Consider my mind blown. Haha so I suppose my next question is what to do about it?

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[Chad91GTZ]

If its not slipping its not locking like Jon said. How was your fuel mileage on the way home when you got the code as compared to previous measurements?

[3X00-Modified]

I'd start with something simple and that is to have it scanned or inspected by someone to verify the theory of the trans not locking the TCC... unfortunately that consists of finding someone with a DHP tuner or hitting up a dealer.

[berettaboy]

If its not slipping its not locking like Jon said. How was your fuel mileage on the way home when you got the code as compared to previous measurements?

It was about the same like two MPG off 28 back and 30 there

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[3X00-Modified]

Just some info if you wanted to "fix" the current valve body, or anyone with the same code.

http://www.sonnax.com/system/announcement/SC-4T60E.pdf

$134 kit that also requires a $150 drill/reamer jig kit to install, and can only be done when pulling the entire valve body. And with a 4t60e if your that far in you might as well just rebuild the dang thing.