P031D

Code

Generic P — Powertrain

Ignition D Control Signal Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 34 RU: 23

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Page language: EN

Causes

Broken or open wiring between ECM and ignition coil/module D
Corroded/loose connector at coil/module D or ECM
Faulty ignition coil or coil pack (D channel)
Failed ignition driver inside the ECM/PCM
Short to voltage or short to ground in the control circuit
Poor or missing ground or battery power to coil/module

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Engine misfire or rough idle (may be cylinder-specific)
Reduced power, hesitation or stumble during acceleration
Poor fuel economy
Possible no-start or hard-start condition if coil fails fully

What to check

Scan tool: read freeze frame and live data, confirm code and related misfire codes
Visual inspection of wiring harness, connectors, and coil pack/module D
Check for corrosion, damaged pins, loose terminals at coil and ECM connector
Verify battery voltage supply and ground at the coil/module
Measure coil primary resistance and compare to specification
Perform continuity test from ECM ignition driver pin to coil connector pin

Signal parameters

Expected: a switching (pulsed) control signal from the ECM to coil D during cranking and running — typically a low-side switch to ground or a pulsed 12 V depending on design
Pulse pattern should correspond to ignition timing and engine speed (frequency increases with RPM)
When inactive, control pin may sit at battery voltage or high-impedance; when active, it will be pulled near 0 V (for low-side drivers)
Coil primary: low DC resistance (manufacturer-specific); open/very high resistance indicates a bad coil
Oscilloscope waveform: clear square/pulse waveform with good amplitude and no excessive noise or dropouts

Diagnostic algorithm

Verify and record freeze frame data and any related misfire codes with a scan tool.
Visually inspect coil D, connector, and wiring for damage, corrosion, or loose pins; repair as needed.
With ignition off, check for proper battery voltage at coil power terminal and good ground at coil ground.
Measure coil D primary resistance; if open or out of spec, replace the coil.
Check continuity between the ECM ignition driver pin and the coil control pin; repair any open circuits.
Backprobe the coil control wire while cranking/idle with a DVOM or oscilloscope to confirm pulsed control signal; if no pulse, suspect wiring or ECM driver.
Swap coil D with another known-good coil (if practicable) to determine if the fault follows the coil.
If coil and wiring check good but no control signal from ECM, consider replacing ECM or repairing internal driver only after verifying with manufacturer procedures.
Clear codes and test-drive to confirm repair; monitor for recurrence.

Likely causes

Open/ intermittently open harness connector to ignition coil D
Failed ignition coil (D channel)
Damaged PCM driver transistor for channel D
Corroded connector or poor pin contact at coil or ECM
Blown fusible link or blown ignition-related fuse affecting coil power

Fault status

⚠️ Status

Ignition D control circuit open (no control pulse detected or open circuit) — ECM has detected loss of expected ignition driver activity on channel D.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

Repair manuals