P1860 trouble code.

Dirtautoguy · June 8, 2014

1996 chevy k1500 4l60e

The other morning when I got up to go to work I started my truck as usual and let it run for a minute or two before leaving. I noticed that my check engine light had come on very soon after starting the truck. I have a scan gauge two and it said that I had a p1860 code. I didn't have time to figure that out so I tried to clear it to see if it would go away. But it came right back almost instantly. So I left and noticed that my truck shifted quite hard and not normal.

After driving a fe minutes the light was really bugging me so I cleared it again and it didn't come back and it started shifting normal. I haven't seen the code since and it doesn't shift nearly as hard any more. However it does seem to hesitate to shift down and sometimes shifting up once in a while. I'm pretty sure it's not slipping it will spin the tires pretty easy.

The code apparently means that the circuit to the torque converter clutch pulse modulation solenoid is having problems or that the solenoid is. Does any one know more about this? It seems to have more issues shifting when it's cold. And the fluid looks good and doesn't smell burnt but it probably wouldn't hurt to change it.

Thanks!

gmtech4 · June 8, 2014

shifting hard is a default for the code to get your attention ,,,

while the pan is off you can throw a solinoid at it ......you can guess for something like this but if it still does it again after ,,its out of your hands

Dirtautoguy · June 8, 2014

Hmmm ok. Would you just do the tcc solenoid? Or others too? It usually shifts up ok unless it's cold and once in a while when it's warm. But it has a hard time shifting down it seems like

gmtech4 · June 9, 2014

Hmmm ok. Would you just do the tcc solenoid? Or others too? It usually shifts up ok unless it's cold and once in a while when it's warm. But it has a hard time shifting down it seems like

the code should be diag'd but a solenoid is easy to do

daxr · July 1, 2014

P1860 has been a GM staple for years. It can indicate a sticking solenoid, but I've never actually managed to fix this by throwing in a solenoid. The problem is that GM uses very simple and reliable solenoids to push their very unreliable and sticky old-style plungers through the valve body. More often than not, a valve body rebuild is needed. There's plenty of youtube videos on rebulding valve bodies, but picking up a rebuilt unit is usually the way to go.

You can just ignore the code until you notice problems driving. Usually what happens is the computer thinks things are not getting done how it wants, so it goes to max line pressure and you get harsh shifts, which can eventually cause problems with the rest of the transmission.

Dirtautoguy · July 7, 2014

well i never got the code back and for some reason its just fine now. if it gives me more problems i will look more into it and let you guys know, thanks for the help!

Ron Mason · October 10, 2019

I have a 1996 GMC K-1500. A few years back the transmission went out so I went to AAmco and they replaced it with a newly rebuilt one. After 1 month, the trans went out so I went back to them and they replaced it again. Shortly after that, the engine went out and it sat for 3 years before I could fix it. Now, I am getting 3 different codes...P1860, P1864 and P1886.

The trans only has maybe 1000 miles on it, if even that... I'm guessing because of the time frame that has passed, AAmco won't touch it.

I will say that right after I got it back, the transmission seemed like it shifted really hard.. Almost like it had a shift kit in it, it does not.

It seems to shift fine, both up and down...

What might be my best course of action? I've recently put the truck up for sale. I've got over $30k into it and just want to get rid of it... It's a great truck...

Also, it is lifted about 6 inches and it has 37's on it. I know that's causing quite a bit of drag on the trans, but I never beat it or get on it at all... Like I said, it baely has 1000 miles on the second rebuilt AAmco trans...

Should I even bother calling them to see if there's anything they can do? Obviously it is a problem with the trans they sell.

Thank you

Ron