P0685 - Powertrain Control Module (Pcm) Power Relay Control Circuit/Open

P0685 - POWERTRAIN CONTROL MODULE (PCM) POWER RELAY CONTROL CIRCUIT/OPEN

Description:	Monitors the power sustain relay (PSR) circuit output from the PCM. The test fails if the PCM grounds the PSR circuit, and excessive current draw is detected on the PSR circuit or, with the PSR circuit not grounded by the PCM, voltage is not detected on the PSR circuit. The PCM expects to detect voltage coming through the PSR relay coil to the PSR circuit.
Possible Causes:	Open or shorted PSR circuit Damaged PSR relay Open B+ to PSR relay
Diagnostic Aids:	The PSR relay is used to maintain voltage to the PCM, transaxle control module (TCM) and traction battery control module (TBCM) after the key is turned to OFF position. This is done so an effective discharge of the energy storage components can occur. An open circuit or short to ground can only be detected when the PCM is not grounding the circuit. A short to voltage can only be detected when the PCM is grounding the circuit.
Application		Key On Engine Off	Key On Engine Running	Continuous Memory
All		refer to PINPOINT TEST BA .