Test Procedure
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.
- BA1 DIAGNOSTIC TROUBLE CODE (DTC) P0685: DETERMINE THE DTC BEING DIAGNOSED
- Is DTC P0685 present in the KOEO or KOER self-test?
Yes No GO to BA2. GO to BA7. - BA2 KOEO AND KOER DTC P0685: CHECK THE B+ VOLTAGE TO PSR
- PSR connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
( + ) PSR Connector, Harness Side ( - ) B+ (coil) - Pin 1 (85) Ground - Is the voltage greater than 10.5 V?
Yes No GO to BA3. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - BA3 CHECK THE PSR RELAY
- Key in OFF position.
- Carry out the component test. Refer to the Wiring Diagram, Cell 149 Component Testing to check the PSR relay.
- Is the PSR relay OK?
Yes No GO to BA4. INSTALL a new PSR. CLEAR the DTCs. REPEAT the self-test. - BA4 CHECK THE PSR CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS
- PCM connector disconnected.
- Key ON, engine OFF.
- Measure the voltage between:
( + ) PSR Connector, Harness Side ( - ) PSR - Pin 2 (86) Ground - Is the voltage less than 1 V?
Yes No GO to BA5. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - BA5 CHECK THE PSR CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS
- Key in OFF position.
- Measure the resistance between:
( + ) PSR Connector, Harness Side ( - ) PSR - Pin 2 (86) Ground - Is the resistance greater than 10K ohms?
Yes No GO to BA6. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - BA6 CHECK THE PSR CIRCUIT FOR AN OPEN IN THE HARNESS
- Measure the resistance between:
( + ) PSR Connector, Harness Side ( - ) PCM Connector, Harness Side PSR - Pin 2 (86) PSR - Pin B27 - Is the resistance less than 5 ohms?
Yes No GO to BA9. REPAIR the circuit.
CLEAR the DTCs. REPEAT the self-test. - Measure the resistance between:
- BA7 CONTINUOUS MEMORY DTC P0685: CHECK FOR AN INTERMITTENT SHORT TO GROUND IN THE PSR CIRCUIT
- PCM connector disconnected.
- Connect a non-powered test lamp between:
( + ) Vehicle Battery ( - ) PCM Connector, Harness Side Positive terminal PSR - Pin B27 - Key ON, engine OFF.
- Observe the test lamp for an indication of a concern while completing the following. (Note that the lamp illuminates when a concern is detected).
- Shake, wiggle, and bend the PSR circuit(s).
- Lightly tap on the PSR to simulate road shock.
- Is a concern indicated?
Yes No ISOLATE the concern and REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.GO to BA8. - BA8 CHECK FOR AN INTERMITTENT OPEN IN THE PSR CIRCUIT
- Key in OFF position.
- PSR connector disconnected.
- Measure the resistance between:
( + ) PSR Connector, Harness Side ( - ) PCM Connector, Harness Side PSR - Pin 2 (86) PSR - Pin B27 - Observe the DMM for an indication of a concern while completing the following. (Note that resistance changes suddenly when a concern is detected).
- Shake, wiggle, and bend the PSR circuit.
- Lightly tap on the PSR to simulate road shock.
- Is a concern indicated?
Yes No ISOLATE the concern and REPAIR as necessary.
CLEAR the DTCs. REPEAT the self-test.Unable to duplicate or identify the concern at this time.
refer to PINPOINT TEST Z . - BA9 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Visually inspect for:
- pushed out pins
- corrosion
- Connect all the PCM connectors and make sure they seat correctly.
- Carry out the PCM self-test and verify the concern is still present.
- Is the concern still present?
Yes No INSTALL a new PCM. REFER toFLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.