Test Procedure

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.

BA1 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	Ground

Is the voltage greater than 10.5 V?

Yes	No
Key in OFF position. GO to BA3.	REPAIR the open circuit.

BA3 CHECK THE PSR RELAY

Carry out the component test. Refer to COMPONENT TESTING to check the PSR relay.

Is the PSR relay OK?

Yes	No
GO to BA4.	INSTALL a new PSR.

BA4 CHECK THE PSR CIRCUIT FOR A SHORT TO POWER 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
Key in OFF position. GO to BA5.	REPAIR the short circuit.

BA5 CHECK THE PSR CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS

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 short circuit.

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 open circuit.

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 fault while completing the following. (Note that the lamp illuminates when a fault is detected).
- Shake, wiggle, and bend the PSR circuit(s).
- Lightly tap on the PSR to simulate road shock.

Is a fault indicated?

Yes	No
Key in OFF position. ISOLATE the fault and REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.	Key in OFF position. GO to BA8.

BA8 CHECK FOR AN INTERMITTENT OPEN IN THE PSR CIRCUIT

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 fault while completing the following. (Note that resistance changes suddenly when a fault is detected).
- Shake, wiggle, and bend the PSR circuit.
- Lightly tap on the PSR to simulate road shock.

Is a fault indicated?

Yes	No
Key in OFF position.	Key in OFF position.
ISOLATE the fault and REPAIR as necessary.	Unable to duplicate or identify the fault at this time.
CLEAR the DTCs. REPEAT the self-test.	GO 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 to FLASH 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.