Pinpoint Test B : System Voltage Low Or Battery Is Discharged: Notes
Diagnostic Overview
Diagnostics in this service information assume a certain skill level and knowledge of Ford-specific diagnostic practices. Refer to Diagnostic Methods in Service Information for more information.
Refer to CHARGING SYSTEM for schematic and connector information.
Normal Operation and Fault Conditions
With the engine running, the charging system supplies voltage to the battery and the electrical system through the high current BJB and battery B+ cable. The PCM monitors this voltage. If voltage drops 1.5 volts or more below the generator voltage desired, these DTCs can set after 30 seconds.
NOTE:
DTC P0562 or P1397 can be set if the vehicle has been recently jump started, the battery has been recently charged or the battery has been discharged. The battery may become discharged due to excessive load(s) on the charging system from aftermarket accessories or if vehicle accessories have been operating for an extended period of time without the engine running.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P0562 | System Voltage Low | This DTC sets if the PCM detects voltage from the charging system that is 1.5 volts lower than the generator voltage desired. |
| P1397 | System Voltage Out of Self-Test Range | The PCM sets this DTC if the voltage rises above or drops below the calibrated setpoint. This DTC can also set if the vehicle has been recently jump started or has had a discharged battery. |
| U3003:16 | Battery Voltage: Circuit Voltage Below Threshold | Sets in the BCM when the BCM detects that battery voltage has dropped below 9 volts from the voltage supply circuit. |
Possible Sources
- Battery
- Engine, generator and battery grounds
- Fuses
- Generator
- PCM
- Wiring, terminals or connectors
Visual Inspection and Diagnostic Pre-checks
- Verify the fusible links.
- Inspect for abnormal ignition-off current drain(s).
- Inspect the battery.
- Inspect the wiring, terminals or connectors.
- Inspect for loose or corroded connections.
- Inspect high current BJB for loose or corroded connections.