Code : P1637
Make : GMC
Description : P1637 GMC Generator L-Terminal Circuit
Possible causes :
– Faulty Generator (Alternator)
– Generator harness is open or shorted
– Generator circuit poor electrical connection
– Powertrain Control Module (PCM) programming
– Faulty Powertrain Control Module (PCM)
Solutions :
– Carry out a Reset via CarDiag
– Choose a better quality fuel
– Check that the tank cap is securely closed
– Check the oil level and add more if it is lower than MAX
– Restart an Automatic diagnostic via CarDiag
– If the fault persists, you can check the “Possible causes” listed above : visually inspect (by yourself (tutorials to come) or by a professional) the wiring harness and the associated connectors, check for damaged components, and look for broken, bent, pushed, or corroded connector pins.