Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
P0685 - Powertrain Control Module (Pcm) Power Relay Control Circuit/Open
2003 Ford Windstar BaseSECTION P0685 - Powertrain Control Module (Pcm) Power Relay Control Circuit/Open
WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
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: |
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| 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 . | |||
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.