P0384 moderate

Glow Plug Control Module Circuit High

The P0384 code means the vehicle's onboard diagnostic system has detected: Glow Plug Control Module Circuit High. This is a moderate severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
hard
Estimated cost
$150 - $600 (parts and labor)
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Common Symptoms

  • Check Engine Light on
  • Glow plugs may not activate
  • Hard starting in cold temperatures
  • No glow plug indicator on dashboard

Probable Causes (Ranked by Likelihood)

  • Open circuit in glow plug module wiring Very High
  • Failed glow plug control module High
  • Disconnected module connector Moderate
  • PCM not sending control signal Low

Frequently Asked Questions

What happens when the glow plug module fails?

The glow plugs will not activate during cold starts, making the engine very difficult to start in cold weather. Once running, the engine operates normally.

Can I bypass the glow plug module?

It is not recommended. The module controls timing and duration of glow plug operation. Manual bypassing can damage glow plugs or cause a fire hazard.

How much does the glow plug module cost?

The module costs $100-$400 depending on the vehicle. Labor is typically $100-$200 for replacement.

Mechanics Guide Step-by-step diagnosis

Step-by-Step Diagnostic Procedure

  1. Check module connector is fully seated.

  2. Verify power and ground supply to the module.

  3. Check PCM control signal to the module.

  4. Replace module if inputs are correct but it does not activate glow plugs.

Sources 1

This page is built from documented references. Verify against your own service info before repair work.

  • SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)

Commonly Affected Vehicles

  • 2010-2020 Ford F-350 (6.7L Diesel)
  • 2012-2019 Chevrolet Silverado 3500 (6.6L Duramax)
  • 2008-2018 Ram 3500 (6.7L Cummins)
  • 2011-2020 GMC Sierra 3500 (6.6L Duramax)

Related Codes

P0380P0383P0382

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