I have a 1999 chevy blazer with a code p1870. Anyone know What code this is? I know its the transmission But idk what part? Is it safe to drive like this? It only hits hard ****fting to second gear.Its seems to only do it when its hot. Its a family car... I really dont wont to take it to the shop and drop all that money. when it could be somthing simple i can fix myself. Anyones help will be greatly appreciated.

 

welcome to BF from Canada

I did a google on your error code and this is what poped up

GM service bulletin about code p1870

 

I already looked at all that I need someone who has had this problem them selves. I done all the research.

 

Welcome from Utah.

Check out the DTC section on this site. Great info on what the issue may be or how to fix it.

 

welcome from NC.

 

I had the exact same problem with my '96 when I bought it. You're fine still driving it in the short term, but I would get the problem taken care of soon. Any transmission shop can do it for you, or you could do it yourself.

You can either purchase a repair kit with the replacement solenoid, which requires reaming out the valve body location very carefully, or you can usually find upgraded valve bodies on eBay with the solenoid already replaced. That's what I did, and the replacement valve body I bought came with good instructions and all the gaskets necessary. It took me a couple hours to drop the pan, remove the valve body and install the new one. I also replaced the transmission filter since I was already in there. When you replace the transmission fluid, remember that you're only replacing what was in the pan, so it will probably only be a couple quarts. If you do decide to tackle this yourself I believe I still have the pictures I took of the process, and can dig them up and post them.

 

That would be great. Thank you so much. If you dont mind posting them pics I would highly appreciate that. Thanks again!!!

 

Buy a rebuilt valve body off ebay $90.00. Easy job just count the ***** and get a new gaskets. Two messy hours. Videos on you tube

 

You can kill 2 birds with one stone by installing a trans cooler instead of the valve body. It keeps trans fluid temp well below 200F, which is what triggers the harsh 1-2 upshift. Had that same issue about 7 or 8 years ago, no harsh shift since. Totally bypassed the OEM trans cooler in the radiator and installed one of these: Buy Imperial Maxi-Kool® XL Transmission Oil Cooler 243012 at Advance Auto Parts

 

I had the same issue with my '98 Jimmy last fall. I bought the FitzAll TCC Valve and installed it myself. It was about $20 and wasn't difficult to install. I found out about it by searching here on the Blazer Forum. While I had the valve body off the transmission I also put in an orange box shift kit. It solved the problem and now the transmission shifts beautifully. There was no need to ream the valve body for this particular solution which made it very nice.

Here's the valve I bought: TCC VALVE from Teckpak / Fitzall