Codes P0685, P0977 and P0974

Hi,

Based on the codes, it sounds like you are having issues with the transmission. Both shift solenoid A and B are open. Basically, there is no connection to the ECM or power supply.

The first thing that shows be done is to clear the codes and then restart the engine. Allow it to run for approximately 10 minutes. Turn it off and rescan to see if the code is pending (P0685). If it is, then the ECM should be flashed.

As far as the solenoids are concerned, I attached the diagnostics below. They start out the same as the 685 code, but if they fail, there are steps for testing to determine the cause. Ultimately, either there is an ECM issue or a wiring issue between the ECM and the shift solenoid circuits. It could be as simple as corrosion at the ECM connector or a broken wire between the two.

Take a look through the diagnostics below and let me know if it is something you feel comfortable doing. Wiring can be difficult to trace. However, on a good note, the codes seem like an electrical issue and nothing mechanical in the transmission.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.