TC stopped locking up,1870 code.
Thread Starter
Launching!
Joined: Jun 2006
Posts: 225
Likes: 9
From: Hudson Valley NY
TC stopped locking up,1870 code. I have a 99 Chevy Silverado,4L60E.Rebuilt the trans last winter,Everything worked fine up untill about a month ago the TC stopped locking up got the 1870 code.Everything else works fine.I took the valvebody off checked the solenoids,They checked out OK.Put everything back together had the truck on jack stands and scanned the trans with EFILive put it in 3rd gear and here's what I got.TCC duty cycle-100%,TCC mode-off,TCC enable solenoid-off,TCC enable status-off,TCC fully locked-no,TCC at max press.-yes,TCC state-no.Then when I commanded TC lockup this is what I got.TCC duty cycle-100%,TCC mode-off,TCC enable solenoid-on,TCC enable status-on,TCC fully locked-no,TCC at max press.-yes,TCC state-on.The TCC enable solenoid would not come on by itself.I checked the bore that sometimes wear's out in the vb,But it was fine,No wear.I forgot to add that it does lock up when I command it and when I put my foot on the brake the truck wants to stall out,So it has to be locked.Could it be a broken seal?What else can I check...............Paul
Last edited by DRIVER456; Aug 29, 2010 at 06:34 AM.
P1870 will inhibit lockup, when set (even immature).
TCC slip will set off P1870. You should look at TCC
slip RPM in normal driving, more than few RPM can lead
to P1870 is you have it sustain for more than (I think)
10 seconds (like a long grade at light throttle, with the
line commanded at 0% like it does).
It may just want more pressure (what kind of converter?
any mods / tuning that might have light-load airflow
messed up, reporting low?).
TCC slip will set off P1870. You should look at TCC
slip RPM in normal driving, more than few RPM can lead
to P1870 is you have it sustain for more than (I think)
10 seconds (like a long grade at light throttle, with the
line commanded at 0% like it does).
It may just want more pressure (what kind of converter?
any mods / tuning that might have light-load airflow
messed up, reporting low?).
Thread Starter
Launching!
Joined: Jun 2006
Posts: 225
Likes: 9
From: Hudson Valley NY
I kept the stock TC in.The truck/trans had 90,000mi before I rebuilt it.I put the motor from my Corvette in the truck and I had a set of Patriot perf heads laying around ,Plus a small cam 
Pretty much everything in the trans is heavyduty stuff,Servo's,Clutch's,etc.Like I said it was fine for about 8 months.I have been towing the Vette to the track in OD,But I have the HD servo from PATC.The TC locks with EFILive though when I command it from the scan tool and I also raised all the pressure's for the TC.I'm just trying to see if I can fix it without taking the trans out,But if I have to,Oh well.............Paul
Pretty much everything in the trans is heavyduty stuff,Servo's,Clutch's,etc.Like I said it was fine for about 8 months.I have been towing the Vette to the track in OD,But I have the HD servo from PATC.The TC locks with EFILive though when I command it from the scan tool and I also raised all the pressure's for the TC.I'm just trying to see if I can fix it without taking the trans out,But if I have to,Oh well.............Paul I kept the stock TC in.The truck/trans had 90,000mi before I rebuilt it.Pretty much everything in the trans is heavyduty stuff,Servo's,Clutch's,etc.Like I said it was fine for about 8 months.I have been towing the Vette to the track in OD,But I have the HD servo from PATC.The TC locks with EFILive though when I command it from the scan tool and I also raised all the pressure's for the TC.I'm just trying to see if I can fix it without taking the trans out,But if I have to,Oh well.............Paul
Thread Starter
Launching!
Joined: Jun 2006
Posts: 225
Likes: 9
From: Hudson Valley NY
I cleaned out the radiator,I didn't clean out the TC though,But it wasn't dirty.I drained the trans fluid over the weekend and it was nice and red,No metal filings,It was like I just put the fluid in.I'm going to hook up a lockup switch to that brown wire to the PCM.I don't remember the pin# off hand and see what happens this weekend,I'll report back.Thanks for the reply's.....................Paul
Launching!
Joined: Feb 2010
Posts: 285
Likes: 0
From: south florida
I cleaned out the radiator,I didn't clean out the TC though,But it wasn't dirty.I drained the trans fluid over the weekend and it was nice and red,No metal filings,It was like I just put the fluid in.I'm going to hook up a lockup switch to that brown wire to the PCM.I don't remember the pin# off hand and see what happens this weekend,I'll report back.Thanks for the reply's.....................Paul
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Thread Starter
Launching!
Joined: Jun 2006
Posts: 225
Likes: 9
From: Hudson Valley NY
OK,I put in a new TC,Upgraded some internal parts that I didn't do on the rebuild and still no lockup.I hooked up the scanner and the TCC enable solenoid is not coming on.I checked it with an ohm meter before I put everything back together and it was fine.What would cause that not to come on.When I command it with EFIlive it goes on and the engine lugs and almost stalls when I put my foot on the brake,So I know its locking,But the TCC solenoid won't go on by its self.What else can I check..................Paul
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Verdad Gallardo Thread Starter
Launching!
Joined: Jun 2006
Posts: 225
Likes: 9
From: Hudson Valley NY
No misfires and in the scanner it says TCC locked.I think the problem may be the TCC solenoid because in the scanner it says TCC ENABLE SOLENOID OFF and TCC mode says locked.I checked the TCC solenoid before I put it back together and the ohm's were in range.
Thread Starter
Launching!
Joined: Jun 2006
Posts: 225
Likes: 9
From: Hudson Valley NY
FINALLY figured it out!!!! It was all in the freakin tune.I tried every possible combo in the TCC pressure tables and got it.With EFILive I had to zero out TCC minimum press.And zero out TCC Solenoid minimum PWM and now its like I have a 5th gear!!!! Locks up nice. I'm glad I took the trans apart though anyway.I put a higher stall TC in,The beast sun shell and some other stuff.
