I smogged my 1996 GMC SLE 1500 & the code P1870 came up. What do i need to do to fix it?

Answer 1

ok

Answer 2

I own a shop, and what you may have to do to resolve this issue is to have a shift kit installed in the transmission. This kit will make the shifts quicker, thus less slippage can take place. This is a common fault, and the fix is to install a shift kit. You can try to use some stuff called "Lube-Guard" that you can get at Advance Auto Parts, as it will free up any sticking valves in the transmission. A Valve can stick for a Nano-Second and cause this code to set, so anything you do to make the shift faster will usually resolve the issue.
Part 2:
When a transmission shifts gears; it drops off pressure on the prior gear, and applies pressure to engage the next gear. Anything between this is better known as slip. If the change is too close, the vehicle would experience bind because it would be engaged in two gears at the same time. Many valves in the transmission are spring loaded, and when the pressure falls off enough for the spring to overcome the pressure, then the valve will move to another position (shift gears), and send pressure in another direction. Many kits such as Bully Dog will tell you, to keep from experiencing problems with the transmission, a kit should be installed in the transmission, and this kit is a shift kit. If a valve sticks any at all, then you will experience what is called "flare up" in which the transmission actually slips enough to cause the shaft rpm's to indicate a slip. This is done by a sensor in the transmission that detects any quick shaft movement between gears. I'm not fully sure what you mean by "you smogged your GMC", but if you removed things that are required a reading from, then this could have caused it. An example would be to remove the cat converter insides, and the computer would not see enough temp change between the O-2 sensor before the converter, and the O-2 sensor at the exit of the converter, thus the result is a code set. A sensor is available that tricks the computer into thinking the reading is what its supposed to be, but this sensor is expensive, and is for off road use only.
Glad to help out, Good Luck!!!

Answer 3

First off, I don't know why everybody got a thumbs-down, when nearly everybody says that it has to do with the transmission (it wasn't me!).

The code is for a slipping transmission. I had a problem with my 4L60E having a hard time locking the torque convertor in OD under a load; I would have to back out of the throttle to get it to lock up then it would hold just fine. My truck never threw a code because the TC had never actually locked up then slipped.

My problem was I had a worn torque convertor lockup solenoid. There are 2 solenoids that work together to cause the TC to lock up in 3rd and OD. This may or may not be your problem.

I replaced both solenoids ($100 for both from the dealership) myself in the driveway in a little over an hour. Both are about the size of your thumb, one is plug and play, the other will need to be soldered in to the existing wiring harness. Just pull the pan, and they are located at the front of the valve body. Pretty much any shadetree mech could do this fix...

http://www.transmissionpartsusa.com/2004R_700R4_4L60E_TCC_solenoid_p/609-00k77929u.htm

http://www.transmissionpartsusa.com/4L60E_On_Off_3_2_downshift_solenoid_1996_on_p/609-000k77926.htm

The first link is a picture of the actual solenoid. The second link is a picture that is similar to the second solenoid, the PWM (pulse width modulation). Each solenoid is ~$50. Good luck.

Answer 4

There is internal slippage in the transmission. This may not be readily apparent to you, but the PCM has determined that with the converter engaged and the trans in high gear that there is enough slippage to warrant this code. A majority of the time the problem stems from a worn seal(s), or clutch pack. Any way you look at this your transmission will have to come apart to find the culprit.

Answer 5

An 1870 code in a 4L60E transmission most common issue is the valve body leaking and would require replacement of the valve body and spacer plate.

Answer 6

look up the code on the internet to find out what it is and then you'll know what to do because it'll tell you what's not working properly. my truck was giving off three codes and so we looked them up on the internet and found out what the codes stood for. The problem ended up being related to something completely cheap to repair. But that's my advice!
www.engine-light-help.com

Answer 7

Here is a site that explains that transmission problem and makes fix-it suggestions. http://www.automotiveforums.com/t253337-code_1870.html