P0700 Fault code

Jim tait · April 21, 2020

I have a trouble code P0700 which is one of the following Transmission Control System Malfunction. Which could be either
1 Replace faulty solenoid.
2 Replace a faulty transmission valve body.
3 Replace transmission fluid
4 Wire harness issue
5 Replace the transmission control module.

Has anyone had this fault?

davester · April 21, 2020

Actually, P0700 is more of a "there is something wrong with the transmission. get a better code reader that can get a more specific code from the tcm" code...

Jim tait · April 22, 2020

I have the following tester, it is a Launce Creder VII+. What type of tester would you suggest.

davester · April 22, 2020

If that was supposed to be "Launch Creader VII+", then from googling it claims to be able to get codes from the tcm, so you might try reading it's manual to see if you can get it to do that.

But, if this is a vehicle you plan on keep for awhile, and working on yourself, I would suggest getting a knockoff techii. They are relatively cheap now that the latest GM trucks use a newer setup, and they get codes and performance diagnostic and repair procedures with all the computers in your truck.

And if you are wrenching on the truck yourself, I would also suggest signing up for the full-service manual for your truck at a site like alldatadiy.com. It has info on how to diagnose and repair most problems with your truck.

Jim tait · April 22, 2020

Thanks very much. You said that the GM had gone to a newer diagnosis system. What is the name of the older system ‘knockoff techie’

davester · April 22, 2020

I just know it as a TechII (that's the older one), don't know the name of the newer stuff.

tbarn · April 22, 2020

P0700 is just a communication between the ecm and tcm. It doesn't mean much by itself. The tcm cannot turn on the ses by itself so it can send a P0700 to the ecm and direct it to turn on the ses. It CAN be a trans issue but more likely it is an emissions issue. Step 1, any other ecm dtc's? fix them first. Step 2, any other tcm dts's? Fix them. And YES, get a Tech2. For what it's worth. DTC's very rarely equal "replace X part" without further diagnosis.