P1670
Output Driver Module 4 (Quad Driver Module 'C') Fault
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The P1670 code is a GM-specific code indicating that the PCM has detected a fault in its Output Driver Module 4 (also referred to as Quad Driver Module 'C'). Inside the PCM, there are several output driver chips that control various external components like relays, solenoids, and actuators. Each driver has an internal feedback circuit — when the expected voltage doesn't match reality, the PCM logs a fault code.
The tricky part of diagnosing this code is that ODM 4 controls multiple circuits, and the code doesn't tell you which specific circuit has the problem. You'll need to consult the wiring diagram for your specific vehicle to identify which components are controlled by this driver. Common circuits on ODM 4 include A/C compressor relay control, cooling fan relay controls, and various solenoid circuits.
Diagnosis involves disconnecting the circuits controlled by ODM 4 one at a time and clearing the code to see which circuit is causing the fault. Once the faulted circuit is isolated, you can inspect its wiring, relay, or solenoid for shorts or failures. If all external circuits test normal, the PCM's internal driver chip may have failed, requiring PCM replacement. This is best diagnosed by a shop with GM scan tool capabilities.
Severity
Symptoms
- •Check engine light is on
- •Cooling fans may not operate correctly
- •A/C compressor may not engage or engages erratically
- •Engine may idle roughly or run poorly
- •Various electrical accessories may malfunction
Likely Causes
One of the circuits controlled by Output Driver Module 4 — such as the A/C relay, cooling fan relays, or other solenoids — has a short to ground or to power, overloading the driver and triggering the fault.
A failed relay (such as the A/C compressor relay or cooling fan relay) draws abnormal current through the output driver, causing the PCM to detect a fault condition.
Chafed, corroded, or broken wiring in any circuit controlled by this driver module creates an electrical fault that the PCM detects through its internal feedback line.
The output driver chip inside the PCM has failed internally. This requires PCM replacement and is confirmed only after all external circuits check out normally.
A corroded engine or body ground connection shared by ODM 4 circuits creates a high-resistance path that causes voltage readings to fall outside normal parameters.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Identify which circuit on ODM 4 is faulted using a wiring diagram
- Test and replace faulty relays (A/C, cooling fans) controlled by ODM 4
- Inspect and repair damaged or corroded wiring in ODM 4 circuits
- Clean and tighten all related ground connections
- Replace the PCM if internal output driver failure is confirmed