P1870 code
03-31-2009, 11:32 PM
#1
P1870 code I've got a 97 silverado with 111k that recently threw a P1870 code. After a bit of research, it seems this is a common 4L60 code and it was a problem in the valvebody that caused the computer to throw a converter slipping code. Seemed to be a easy fix by installing a transgo SK4L60 shift kit. Bought the kit and had the shop install it and picked it up this morning. It drove great all day, but after a bit of driving, it threw the 1870 code again. The shop had cleared it earlier. After driving some more, it would not down shift. When stopping at a light, I would have to pull it down to 2 manually and shift it on my own. Tried pulling it to 1, but it would still take off in 2. Wouldn't shift to 1 even if done manually. The transmission never had a lick of trouble, even when I dropped it off for the kit. The thing still works as far as shifting goes, but it has to be done manually. Is this a problem that the shop did, or is the trans. taking a dump?
04-01-2009, 10:19 AM
#2
PO1870 happens when the PCM sees excessive slipage with the converter locked and will set high line and or limp mode. You are in limp mpode meaning the PCM has turned itself off.
1- scann for codes again. 2-Clear codes and drive truck if limp mode is still present imediatly and shifts do not resume then you likley have and electrical fault,
3- If P1870 returns you may have bad converter clutch, TCC solenoid, PWM solenoid, Wear in the input stator bushings, Bad or leaking input shaft oring.
When in limp mode you will only be able to select manual 2nd and 3rd gears.
1- scann for codes again. 2-Clear codes and drive truck if limp mode is still present imediatly and shifts do not resume then you likley have and electrical fault,
3- If P1870 returns you may have bad converter clutch, TCC solenoid, PWM solenoid, Wear in the input stator bushings, Bad or leaking input shaft oring.
When in limp mode you will only be able to select manual 2nd and 3rd gears.
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04-01-2009, 11:39 AM
#3
Thanks for the explanation. The guy that did the shift kit install just said to rebuild it, with no other explanation. The truck seems to run great as long as I don't pull something. Once you load it up, then the code comes on. May be the converter slipping? Before the shift kit, the light was on w/1870 code, but it would still run through the gears, up and down, just fine. Now the light is on w/ no down shifting.....
04-01-2009, 04:31 PM
#5
Just went outside to reset the code and releave myself from "limp mode" and decided to look underneath. My under carraige is covered in transmission fluid. This happened to me once before a long time when I put a little to much fluid in and pulled a load. I guess it built up pressure and forced it out the vent. I warmed the truck up a checked the fluid with the truck in neutral and there is WAY to much fluid in the tranny. I'd say it is roughly 2" over the hot/full line. "Could" this be a problem or am I just grasping for anything I can get..... BTW, fluid is coming from the vent.
04-01-2009, 05:48 PM
#7
On to another random test...... I cleared the code and went for a ride. It did fine for the most part, but it did get hung in second once at a stop sign and wouldn't kick down to first for the take off. I laid into the gas and it down shifted, ran up and chirped second like no ones business. When I got back to the drive way, I manually pulled it to first and goosed it, it jumped as it should. Then I manually put it in second, goosed it, and it just barely moved, as if it wouldn't go to 1. Put it in 3, it jumped as it should, and OD jumped as well. For some reason, when I put it in 2, it won't drop to 1, but all other gears will. Seems like something is fishy with 2nd gear......
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04-01-2009, 08:20 PM
#9
Ok, you learn something new every day.
Well, guess I'm back on my fluid scenario then. The code has been cleared and the truck seems to be doing ok. I have to pull the boat tomorrow so we will see if it acts up. I have a speacial pump that can remove some fluid, I just need to get a legnth of small diameter hose to reach down the dipstick tube.
Well, guess I'm back on my fluid scenario then. The code has been cleared and the truck seems to be doing ok. I have to pull the boat tomorrow so we will see if it acts up. I have a speacial pump that can remove some fluid, I just need to get a legnth of small diameter hose to reach down the dipstick tube. 