What does code P1634 mean?

Q: What does code P1634 mean?

Ignition 1 Power Circuit Low Voltage. P1634 on a GM vehicle means the powertrain control module (PCM) has detected that the voltage on its dedicated Ignition 1 power input is lower than expected while the ignition is on. This circuit feeds the PCM's internal logic and injector drivers, so the module flags the fault when that supply falls below its calibrated threshold.

DTC codes / GM codes / P1634

P1634 · GMIgnition 1 Power Circuit Low Voltage

P1634 on a GM vehicle means the powertrain control module (PCM) has detected that the voltage on its dedicated Ignition 1 power input is lower than expected while the ignition is on. This circuit feeds the PCM's internal logic and injector drivers, so the module flags the fault when that supply falls below its calibrated threshold.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.