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Help got a P1870 Code

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Old 08-12-2006, 11:57 AM
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Default Help got a P1870 Code

Ok I just got a P1870 code. The trans feels like its shifts into gear kind of hard. Its on a 1998 C5 with 45k. It has a 3500 yank stall in it and might have had a shift kit installed, not sure but would think so because of all the other work that was done to the car. Any thoughts?
Old 08-12-2006, 06:59 PM
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I've gotten this code only in relation to TCC slippage.
You might try and get the low-load line pressure bumped
up (HPTuners now has controls for the line bump for
TCC applied as well as other modes). This is what I had
to do, but more primitively at the time. You can also
add a couple of hundred RPM to the slip threshold for
that code.
Old 08-13-2006, 08:27 PM
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I'd have to check alldata again but if I remember right thats a tranny slippage code and GM used to have us change them under warrantee for it. I'll try to check it out for sure if I can pull up my alldatapro crap....
Old 08-13-2006, 08:40 PM
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OK, pulled up the specs on the code and it reads as follows;
p1870- trans component slipping
DTC stored in PCM
PCM inhibits TCC engagement
PCM commands max line pressure
PCM inhibits 4th gear if in hot mode
PCM freezes shift adapts from being updated

I'm almost certain this was the "death code" when I worked for GM a few years ago(before I got smart and got out!! lol) It may have been a fluke that caused it but I seem to remember more junk tranny's with that code than almost any other....except the good old broken sunshells.....
Old 08-14-2006, 10:46 AM
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Well, a slipping (in the clutch packs) trans
will set this code too I'm sure, but there are
non-fatal ways to see it as well. A scan tool
will show you where in the chain the slip is,
if you look at engine, input, output shaft
speeds with current gear figured in.
Old 08-14-2006, 11:54 AM
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Originally Posted by jimmyblue
A scan tool
will show you where in the chain the slip is,
if you look at engine, input, output shaft
speeds with current gear figured in.
not all scan tools have the capabilities to show shaft speeds etc. Most will only flash you the code and from there you have to guess. "Generally" speaking when I worked for chevrolet(for many years) a p1870 was death coming(sometimes slowly) to a tranny, whether a 4l60 or 4l80 either one.
If you have access to a tech2 you'll get the most dynamic reading of what is actually happening and also get a good look at the trans adapts as well. The snap-on or MAC scanner is probably the next best thing but pricey for the normal person who doesn't use it to make a living.



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