Generator F-Terminal Circuit
2014-2016 Chevrolet Spark EV Electric Motor
Description
The PCM detected a fault on the generator (alternator) F-terminal (field) circuit. The F-terminal circuit controls the generator field current to regulate charging voltage.
Symptoms
- Battery light on
- Overcharging or undercharging
- Battery damage from overcharging
- Dim lights
Common Causes
- Faulty generator/alternator
- F-terminal wiring damage
- PCM control driver failure
- Corroded connector
Diagnostic Steps
- Test generator field voltage
- Inspect F-terminal wiring
- Test generator output regulation
- Check PCM field control signal
Repair Notes
Test and replace generator if field control is faulty. Inspect wiring.
Related Codes
Other Powertrain Codes
- P0070Ambient Air Temperature Sensor Circuit
- P0071Ambient Air Temperature Sensor Range/Performance
- P0072Ambient Air Temperature Sensor Circuit Low
- P0073Ambient Air Temperature Sensor Circuit High
- P0115Engine Coolant Temperature (ECT) Sensor 1 Circuit
- P0116ECT Sensor 1 Circuit Range/Performance
- P0117ECT Sensor 1 Circuit Low Input
- P0118ECT Sensor 1 Circuit High Input
- P0119ECT Sensor 1 Circuit Intermittent
- P0125Insufficient Coolant Temperature for Closed Loop Fuel Control
P1638 on Other Vehicles
Chevrolet Astro
1995-2005 4.3L V6 Vortec
Chevrolet Avalanche
2002-2006 5.3L V8 Vortec
Chevrolet Avalanche
2002-2006 8.1L V8 Vortec
Chevrolet Avalanche
2007-2013 5.3L V8 Vortec
Chevrolet Avalanche
2007-2013 6.0L V8 Vortec
Chevrolet Aveo
2012-2018 1.6L I4
Chevrolet Beat
2018-2021 1.2L I4
Chevrolet Beretta
1990-1996 2.2L I4
Common Questions
What does code P1638 mean on a 2014-2016 Chevrolet Spark EV?
P1638 stands for "Generator F-Terminal Circuit". The PCM detected a fault on the generator (alternator) F-terminal (field) circuit. The F-terminal circuit controls the generator field current to regulate charging voltage.
What are the symptoms of P1638 on a Chevrolet Spark EV?
Common symptoms of P1638 include: Battery light on, Overcharging or undercharging, Battery damage from overcharging, Dim lights.
What causes P1638 on a 2014-2016 Chevrolet Spark EV?
Common causes of P1638 include: Faulty generator/alternator, F-terminal wiring damage, PCM control driver failure, Corroded connector.