P0383 moderate

Glow Plug Control Module Circuit Low

The P0383 code means the vehicle's onboard diagnostic system has detected: Glow Plug Control Module Circuit Low. 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
  • Extended crank time in cold weather
  • Glow plug indicator stays on too long or not at all
  • White smoke on startup

Probable Causes (Ranked by Likelihood)

  • Short to ground in glow plug module wiring Very High
  • Failed glow plug control module High
  • Corroded module connector Moderate
  • PCM communication circuit fault Low

Step-by-Step Diagnostic Procedure

  1. Check glow plug control module connector for corrosion or damage.

  2. Measure control module supply voltage and ground.

  3. Check communication wiring between PCM and glow plug module.

  4. Replace module if wiring tests good.

Frequently Asked Questions

What is the glow plug control module?

It is an electronic module that controls when and how long the glow plugs operate. It receives commands from the PCM and activates the glow plugs accordingly.

Can a bad module damage glow plugs?

Yes, a malfunctioning module can over-energize glow plugs, causing them to burn out prematurely or overheat.

Where is the glow plug control module?

It is typically mounted on the engine near the glow plugs. On Ford diesels, it is on the passenger side valve cover area.

Sources

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

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