Generator L-Terminal Circuit
Table of contents
P1637 BUICK 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)
How do I fix code P1637 BUICK?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Cost of diagnosing the P1637 BUICK code
The cost of diagnosing the P1637 BUICK code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
When is the code detected
When the Powertrain Control Module (PCM) detects a fault (circuit shorted to ground, or circuit shorted to a voltage), the P1637 code will set.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P1637 BUICK Description
The L-terminal circuit from the generator is a discrete circuit (a discrete circuit has no splices and only one source and one destination) into the Powertrain Control Module (PCM). The PCM applies ignition voltage to the generator L terminal circuit. A small amount of current flows from this circuit through the generator windings to create a magnetic field which starts the generator process. When the generator is at operating speed and producing voltage, a solid state switch for the L terminal circuit in the generator opens and the PCM detects that the initial startup current flow has stopped.
The PCM expects to detect low voltage on the L terminal circuit prior to the generator rotating at operating speed and conversely expects the circuit to be at ignition voltage potential when the generator is operational.