P0563

Code

Generic P — Powertrain

System Voltage High

Brand: Generic

Type: P — Powertrain

Views: UK: 33 EN: 55 RU: 63

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Page language: EN

Causes

Faulty alternator voltage regulator (internal or external)
Defective alternator (overcharging)
Failed voltage regulator in PCM/BCM (controller-driven regulator)
Shorted or damaged wiring in the voltage sense or generator control circuit
Poor or corroded ground or B+ connections causing false readings
Aftermarket charging devices, battery chargers, or incorrect replacement parts

Symptoms

Battery/charge warning lamp or MIL illuminated
Bulbs or fuses blowing prematurely
Electrical components failing or acting erratically
Battery overheat or unusual smell from battery compartment
Unstable or high dashboard voltage readings (needle or gauge erratic)
Possible reduced lifespan of battery and electronics

What to check

Scan for stored freeze frame and related codes; note voltage at time of fault
Measure battery voltage (engine off and engine running) with a quality multimeter
Observe charging voltage with engine at idle and at higher RPMs; check for > normal range
Inspect battery terminals, main ground straps, alternator B+ and sense connections for corrosion, looseness or damage
Visually inspect wiring harness to alternator/PCM for shorts, chafing or aftermarket connections
Check for aftermarket chargers, isolators or jump-start devices connected to the system

Signal parameters

Battery voltage, engine off: ~12.4–12.9 V (typical, depends on battery state)
Charging voltage, engine running: normally ~13.5–14.8 V (typical range)
High-voltage fault trigger: often above ~15.5–17.0 V (manufacturer-specific threshold)
AC ripple: should be low; excessive ripple indicates diode/regulator problems
Voltage sense circuit continuity: low resistance to battery B+ terminal

Diagnostic algorithm

Retrieve DTCs and freeze frame with a scan tool. Note reported voltage and conditions when code set.
Perform visual inspection: battery, terminals, main grounds, alternator connectors, fuses and any aftermarket devices.
With a fully charged battery, measure battery voltage with engine off to confirm baseline.
Start engine and measure charging voltage at battery and alternator B+ at idle and at ~2000–3000 RPM. Compare to typical charging range.
If overvoltage present, disconnect non-essential aftermarket accessories and re-check to rule out external feeding.
Use a scan tool to monitor alternator/regulator status, duty cycle or field control values (if applicable).
Check for excessive AC ripple (diode failure) with an oscilloscope or multimeter (millivolt AC).
Inspect and test the voltage sense circuit and regulator wiring for shorts to voltage or open circuits; repair any damaged wiring.
If wiring and connections are good, bench-test or replace the alternator (or voltage regulator module) per manufacturer procedure.
If alternator tests good, consider PCM/BCM voltage sense/regulator diagnostics and possible replacement or reprogramming as a last step.
Clear codes and road-test to confirm the fault does not return; re-scan for related codes.

Likely causes

Alternator regulator stuck closed or failed, causing overcharging
Voltage sense wire shorted to a higher-voltage source or to an incorrect terminal
PCM/BCM internal regulator or sense input fault
Loose or corroded negative or positive battery connections creating transient high readings
Aftermarket accessory (charger, isolator) feeding battery with excessive voltage

Fault status

⚠️ Status

Control module detected charging system voltage above allowable threshold; fault stored when voltage exceeded manufacturer limit. Freeze-frame and related charging system data may be recorded.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

Repair manuals