DTC P0685: Power Sustain Relay (PSR) Primary Circuit Malfunction
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
P0685 - POWER SUSTAIN RELAY (PSR) PRIMARY CIRCUIT MALFUNCTION
| Description: | Monitors the 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: |
|
||
| Diagnostic Aids: | The PSR relay is used to maintain power to the PCM, TCM and TBCM after the key is turned off. 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 power can only be detected when the PCM is grounding the circuit. | ||
| Application | Key On Engine Off | Key On Engine Running | Continuous Memory |
| All | GO to Pinpoint Test BA . | ||