What does it mean?
A stored code P0885 simply means that the PCM has detected an open condition in the power relay control circuit for the transmission control module (TCM). Open could be translated as disconnected or cut for diagnostic purposes. Usually the TCM is integrated into a single housing with the engine control module (ECM). This integrated assembly is known as the powertrain control module (PCM).
Even though they are integrated, the portion of the module which controls (automatic) transmission function may be powered up separately from the ECM. The TCM is typically powered using switched (only present with the ignition switch in the ON, start, or run position) voltage. The TCM power relay control circuit is generally constructed with a fuse and/or a fusible link. A relay is used to initiate a smooth transference of voltage to the respective component without danger of a power surge.
The PCM and TCM are most often powered using the same relay, despite using separate circuits. Gain access to a reliable vehicle information source for details of the TCM power relay control circuit as it applies to the vehicle in question. The PCM performs a self-test (of all controllers) each time the ignition switch is turned on.
If there is not an acceptable TCM power relay control voltage signal (battery voltage), a code P0885 will be stored and a malfunction indicator lamp may be illuminated, The TCM will also enter limp-in mode, on some models, if a code of this type is stored.