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Home / DTC / P0383 — Glow Plug Control Module 1 Control Circuit Low

P0383 — Glow Plug Control Module 1 Control Circuit Low

Detailed page for trouble code P0383.

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11,846generic
22,491specific
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P0383

Generic P — Powertrain

Glow Plug Control Module 1 Control Circuit Low

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in glow plug control circuit
  • Poor or corroded connector pins at glow plug control module or harness
  • Failed glow plug control module (driver)
  • Blown glow plug fuse or failed relay
  • One or more shorted/failed glow plugs drawing abnormal current
  • Weak battery or poor main power/ground to module

Symptoms

  • Malfunction Indicator Lamp (MIL)/check engine light illuminated
  • Extended cranking or hard cold start (diesel engines)
  • Glow plug indicator/warning lamp behavior abnormal
  • Rough idle or misfire after start in cold conditions
  • Possible reduced engine performance until system reset/repair

What to check

  • Read and record freeze frame and live data with a scan tool; note glow plug command and feedback values
  • Verify battery voltage and charging system before testing (clean battery terminals)
  • Visually inspect harness, connectors, and module for damage, corrosion, water intrusion
  • Check glow plug fuse(s) and relay(s) for continuity and correct operation
  • Backprobe module control and feedback terminals while commanding glow plugs ON; observe voltage/current
  • Measure resistance/current draw of individual glow plugs per service spec

Signal parameters

  • Glow plug control output voltage when commanded ON: near battery voltage (typically ~10–14 V) — consult vehicle spec
  • Glow plug control output when OFF: near 0 V
  • Individual glow plug resistance (typical range, varies by design): roughly 0.3–3 ohms — check service manual for exact value
  • Total current draw for bank when commanded ON: can be tens of amps (varies by engine and number of glow plugs) — measure with clamp meter
  • If module uses PWM/current feedback, expect a modulated duty signal and corresponding current feedback; low feedback indicates open/short or driver failure

Diagnostic algorithm

  1. Safety: Park vehicle, apply parking brake, wear PPE. Disconnect battery only if required by the service manual for specific tests.
  2. Read codes and freeze frame with a scan tool. Clear the code then attempt to re-run to confirm repeatability.
  3. Verify battery voltage ≥ 12.4 V with engine off. Ensure charging system healthy while performing tests.
  4. Inspect visually: check glow plug control module connectors, wiring for damage, corrosion, burns, or repairs.
  5. Check related fuses and relay(s). Replace if blown or suspect. Re-test for code presence.
  6. With a scan tool, command glow plugs ON and monitor the module command output and feedback channel. Note voltages/currents.
  7. Backprobe the module: measure voltage at the control output(s) during commanded ON. If output is low, suspect wiring or driver/module failure.
  8. Measure resistance of each glow plug to ground and compare to spec. Look for shorted (very low) or open (very high) plugs.
  9. Measure current draw for the glow plug bank when commanded ON using a clamp meter. Abnormally low or zero current indicates open circuit; excessive current indicates short/failed plug.
  10. If wiring and glow plugs test OK, bench-test or replace the glow plug control module (or swap with known-good if available) and re-check operation.
  11. If module replacement fails to clear the fault, consider ECM/PCM fault and consult manufacturer procedures/updates before replacement.
  12. After repair, clear DTCs, perform cold-start checks and a short drive cycle or test cycle to confirm the repair. Re-scan for any new codes.

Likely causes

  • Damaged harness to Glow Plug Control Module 1 (abrasion, rodent damage, chafing)
  • Corroded/loose connector at module causing low feedback voltage
  • Failed glow plug driver inside control module
  • Blown fuse or defective relay supplying the module
  • Individual glow plug with internal short to ground

Fault status

⚠️ Status
Glow Plug Control Module 1 Control Circuit Low — the control circuit or feedback for Glow Plug Control Module 1 is reporting lower-than-expected voltage/current. Indicates possible open/short, poor connection, blown fuse/relay, failed glow plug(s), or defective control module. Further diagnosis required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

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Code

P0383

LAND ROVER P — Powertrain

Control of the control module of incandescent bulb - low circuit

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in glow plug control circuit
  • Poor or corroded connector pins at glow plug control module or harness
  • Failed glow plug control module (driver)
  • Blown glow plug fuse or failed relay
  • One or more shorted/failed glow plugs drawing abnormal current
  • Weak battery or poor main power/ground to module

Symptoms

  • Malfunction Indicator Lamp (MIL)/check engine light illuminated
  • Extended cranking or hard cold start (diesel engines)
  • Glow plug indicator/warning lamp behavior abnormal
  • Rough idle or misfire after start in cold conditions
  • Possible reduced engine performance until system reset/repair

What to check

  • Read and record freeze frame and live data with a scan tool; note glow plug command and feedback values
  • Verify battery voltage and charging system before testing (clean battery terminals)
  • Visually inspect harness, connectors, and module for damage, corrosion, water intrusion
  • Check glow plug fuse(s) and relay(s) for continuity and correct operation
  • Backprobe module control and feedback terminals while commanding glow plugs ON; observe voltage/current
  • Measure resistance/current draw of individual glow plugs per service spec

Signal parameters

  • Glow plug control output voltage when commanded ON: near battery voltage (typically ~10–14 V) — consult vehicle spec
  • Glow plug control output when OFF: near 0 V
  • Individual glow plug resistance (typical range, varies by design): roughly 0.3–3 ohms — check service manual for exact value
  • Total current draw for bank when commanded ON: can be tens of amps (varies by engine and number of glow plugs) — measure with clamp meter
  • If module uses PWM/current feedback, expect a modulated duty signal and corresponding current feedback; low feedback indicates open/short or driver failure

Diagnostic algorithm

  1. Safety: Park vehicle, apply parking brake, wear PPE. Disconnect battery only if required by the service manual for specific tests.
  2. Read codes and freeze frame with a scan tool. Clear the code then attempt to re-run to confirm repeatability.
  3. Verify battery voltage ≥ 12.4 V with engine off. Ensure charging system healthy while performing tests.
  4. Inspect visually: check glow plug control module connectors, wiring for damage, corrosion, burns, or repairs.
  5. Check related fuses and relay(s). Replace if blown or suspect. Re-test for code presence.
  6. With a scan tool, command glow plugs ON and monitor the module command output and feedback channel. Note voltages/currents.
  7. Backprobe the module: measure voltage at the control output(s) during commanded ON. If output is low, suspect wiring or driver/module failure.
  8. Measure resistance of each glow plug to ground and compare to spec. Look for shorted (very low) or open (very high) plugs.
  9. Measure current draw for the glow plug bank when commanded ON using a clamp meter. Abnormally low or zero current indicates open circuit; excessive current indicates short/failed plug.
  10. If wiring and glow plugs test OK, bench-test or replace the glow plug control module (or swap with known-good if available) and re-check operation.
  11. If module replacement fails to clear the fault, consider ECM/PCM fault and consult manufacturer procedures/updates before replacement.
  12. After repair, clear DTCs, perform cold-start checks and a short drive cycle or test cycle to confirm the repair. Re-scan for any new codes.

Likely causes

  • Damaged harness to Glow Plug Control Module 1 (abrasion, rodent damage, chafing)
  • Corroded/loose connector at module causing low feedback voltage
  • Failed glow plug driver inside control module
  • Blown fuse or defective relay supplying the module
  • Individual glow plug with internal short to ground

Fault status

⚠️ Status
Glow Plug Control Module 1 Control Circuit Low — the control circuit or feedback for Glow Plug Control Module 1 is reporting lower-than-expected voltage/current. Indicates possible open/short, poor connection, blown fuse/relay, failed glow plug(s), or defective control module. Further diagnosis required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-3.0 hours

Similar codes

P0380 P0381 P0382 P0384 P0385 P0386
320

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LAND ROVER

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