Vehicles have computers that run specific vehicle systems by changing certain variables in their operation. Two of these computers are the engine control module (ECM) and transmission control module (TCM). The P0864 code, or other related trouble codes, can be stored if there are communications problems between these two components.
The P0864 code is defined as “TCM Communication Circuit Range/Performance.” This code is triggered when the TCM can’t communicate with the ECM or vice versa. When this code is stored, there’s a good chance that there are other stored diagnostic trouble codes (DTCs) related to the ECM or TCM.
This code can also have various transmission-related symptoms because the ECM needs information from the TCM in order to command the right shift timings. Without these two computers working together to help your vehicle run more efficiently, you can expect your vehicle to consume more fuel.
Note: The definition of the P0864 code can be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.
The issues that trigger the P0864 code are commonly caused by the following:
Common symptoms of the P0864 code include the following:
The P0864 can trigger in most modern vehicles. Diagnosing trouble codes related to electrical components might require you to unplug connectors and use a digital multimeter to check for abnormal readings from various sensors. However, keep in mind that the steps for diagnosis and repair can vary, depending on vehicle specifications. This can be incredibly difficult without the right equipment and knowledge. If you aren’t familiar with the process, it’s best to let a mechanic do the job for you to ensure that all steps and protocols are followed correctly.
Without the right tools and technical knowledge, fixing the P0864 code can be frustrating and confusing. It can even lead to further complications down the road if you don’t follow the appropriate repair process. If you aren’t confident in your DIY skills, you can always bring your vehicle to the nearest repair shop and have a professional mechanic do the job for you.
But if you think you have what it takes to fix the problem on your own, make sure to have the right repair information before proceeding. There’s no such thing as a magic bullet that can resolve all trouble codes for every make and model, which is why having vehicle-specific repair information is a must. You can check out Chilton repair manuals or get an ALLDATA subscription to get the right guides for your vehicle.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.