Generator F-Terminal Circuit
2000-2005 Chevrolet Impala 3.4L V6
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
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0011Intake Camshaft Position Timing Over-Advanced Bank 1
- P0012Intake Camshaft Position Timing Over-Retarded Bank 1
- P0013Exhaust Camshaft Position Actuator Circuit/Open Bank 1
- P0014Exhaust Camshaft Position Timing Over-Advanced Bank 1
- P0015Exhaust Camshaft Position Timing Over-Retarded Bank 1
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 2000-2005 Chevrolet Impala?
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 Impala?
Common symptoms of P1638 include: Battery light on, Overcharging or undercharging, Battery damage from overcharging, Dim lights.
What causes P1638 on a 2000-2005 Chevrolet Impala?
Common causes of P1638 include: Faulty generator/alternator, F-terminal wiring damage, PCM control driver failure, Corroded connector.