Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.
4-90 Powertrain DTC Charts and Descriptions
Diagnostic Trouble Code (DTC) Charts and Descriptions
P0686 - ECM/PCM Power Relay Control Circuit Low (Continued)
Diagnostic Aids: Ability to communicate with the PCM when the ignition is in the OFF, ACC, or LOCK position indicates a hard
fault.
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test B.
P0687 - ECM/PCM Power Relay Control Circuit High
Description: This DTC sets when the ignition switch position run (ISP-R) circuit indicates the ignition is in the OFF, ACC, or
LOCK position, and the amount of time the PCM remains powered through the PCM power relay exceeds a predetermined amount of time.
Possible Causes: • PCMRC circuit short to voltage
• Damaged PCM power relay
Diagnostic Aids: Ability to communicate with the PCM when the ignition is in the OFF, ACC, or LOCK position indicates a hard
fault.
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test B.
P0689 - Electronic Control Module (ECM)/Powertrain Control Module (PCM) Power Relay Sense Circuit Low
Description: This DTC sets when the ISP-R and the INJPWRM circuit voltages do not correspond for a calibrated period of
time.
Possible Causes: • Ignition circuit fuse
• ISP-R circuit open
• ISP-R circuit short to ground
• VPWR circuit short to voltage
• INJPWR circuit short to voltage
• Damaged ignition switch
• Damaged fuel pump relay
• Damaged PCM power relay
Diagnostic Aids: The INJPWRM PID voltage reading should be 0 volts when the ignition is in the OFF, ACC or LOCK position.
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test B.
P068A - ECM/PCM Power Relay De-Energized - Too Early
Description: This DTC sets when the non volatile random access memory (NVRAM) write did not complete successfully after
the ignition key was turned OFF, prior to PCM shutdown. This DTC also sets when the PCM power relay is de- energized too early.
Possible Causes: • PCMRC circuit open
• PCM power relay
• Low battery voltage
Diagnostic Aids:
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test B.
P0690 - Electronic Control Module (ECM)/Powertrain Control Module (PCM) Power Relay Sense Circuit High
Description: This DTC sets when the voltage on the ISP-R and the INJPWRM or VPWR circuits do not correspond for a
calibrated period of time.
Possible Causes: • ISP-R circuit short to voltage
• VPWR circuit open
• INJPWRM circuit open
2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.