P1638 OBD Trouble Code

1 result found

P1638 - GM
Type Powertrain - Manufacturer Controlled DTC - Manufacturer Controlled
Description

Generator 'F' Terminal Circuit Conditions
Cause

Engine speed at 500-3000 rpm, engine runtime over 60 seconds, then the PCM detected that the Generator 'F' terminal PWM was 5% or less for 20 seconds

Try also: https://www.obd-codes.com/p1638