What is the code P1682 on a Chevy Cruze?
The Chevy Cruze, like many GM vehicles, uses P1682 as a manufacturer-specific diagnostic code. In most cases, it points to problems with the Powertrain Control Module (PCM) power supply or its data-link with other modules rather than a single sensor fault.
What P1682 means for the Cruze
Code P1682 is a GM-defined entry tied to the PCM’s power input and its communications with the vehicle’s network. On a Cruze, it is commonly interpreted as an issue with the PCM’s power supply, ground path, or data-link (CAN bus) connectivity to other modules such as the body control module or transmission control module. Because it is OEM-specific, the exact wording and scope can vary by year and engine, so a precise definition should be confirmed in GM service information for your exact model.
Common causes
Below is a list of frequent culprits that technicians check when P1682 appears on a Cruze. The items are listed to help you understand where the problem might originate.
- Weak or failing 12-volt battery or an underperforming alternator causing low voltage to the PCM.
- Loose, corroded, or damaged PCM connectors and wiring to the PCM power/ground circuits.
- Poor engine ground or battery negative grounding paths.
- PCM internal fault or a software/firmware issue requiring a reflash or replacement.
- Wiring problems around the ignition switch or the feed to the PCM.
- Data-link (CAN bus) problems between the PCM and other modules (intermittent communication loss).
Addressing these potential causes often resolves P1682, but some Cruze models may require OEM diagnostics or service bulletins for a definitive repair.
How technicians diagnose P1682 on the Cruze
Before starting the diagnostic list, technicians typically follow a structured approach to verify and isolate the fault. The steps below outline the common workflow used by pros and informed DIYers alike.
- Verify battery condition and charging system performance; check resting voltage and voltage under cranking load.
- Inspect relevant fuses, fusible links, and the ignition relay that supply power to the PCM.
- Examine the PCM power and ground circuits at the connectors and at the battery/main ground points.
- Scan the vehicle with a GM-specific or capable diagnostic tool to confirm P1682 and identify any accompanying codes (e.g., P0601, P0606).
- Inspect PCM connectors for corrosion, bent pins, moisture intrusion, or loose connections; reseat and clean as needed.
- Check for CAN bus or data-link communication issues between the PCM and other modules; look for related network trouble codes.
- If power/ground and wiring are sound, consider PCM reprogramming/updates per GM service information; in some cases, PCM replacement is required.
After completing these steps, technicians typically re-test vehicle operation, clear codes, and perform a road test to ensure that the fault does not recur.
What to do next if you see P1682
Because P1682 can involve the vehicle’s power supply, grounding, and communications, it is often best handled by a qualified technician, especially if the checks require probing the PCM connectors or performing a reflash. Start with the basics: ensure the battery and charging system are healthy, inspect fuses and relays, and check visible wiring and grounds. If the issue persists, a professional diagnostic using GM-specific tools can confirm whether the PCM itself needs service or replacement.
Summary
P1682 on the Chevy Cruze is a GM-specific diagnostic code most commonly linked to issues with the PCM’s power supply, ground, or data-link communications. It is not a sensor-specific fault and can be caused by weak battery voltage, blown fuses or relays, wiring or connector problems, grounding issues, or PCM/software faults. A methodical approach—checking power and grounding, inspecting wiring and connectors, scanning with GM tools, and following service bulletins—helps confirm the root cause and determine whether repair involves simple fixes or PCM replacement. When in doubt, consult a trained technician who can perform a thorough diagnostic and apply GM-approved procedures.
