P0351 Ignition Coil ‘A’ Primary / Secondary Circuit - Automotive Repair Guides & Equipment

COMPONENT LOCATION

GENERAL DESCRIPTION

With the ignition switch in the ON or START position, voltage is applied to the ignition coil. Each ignition coil consists of two coils, a primary and secondary coil. The coils are mounted on top of the spark plugs. To energizing the primary ignition coils, the Engine Control Module (ECM) provides the ground for the primary circuit. The ECM uses the crankshaft position sensor and camshaft position sensor signal to time the energizing of the coil. When a primary ignition coil is energized and de-energized, the secondary coil produces a high voltage spike to the attached spark plug.

DTC DESCRIPTION

Checking output signals from ignition coils every 10 sec. under detecting condition, if the signals indicating open or short in the circuit are detected for more than 5 sec., ECM sets this DTC.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible Cause

DTC Strategy

Detects a short to ground, to battery or open circuit

1.	Poor connection

2.	Open or short in harness

3.	Ignition Coil

ECM

Enable Conditions

NO DTC related to this item

Engine running state

11V ≤ Battery voltage ≤ 16V

The above conditions are met > 0.5 sec.

Threshold value

Open or short

Diagnosis Time

Continuous (More than 5 sec.failure for every 10 sec.test)

MIL On Condition

3 driving cycles

SPECIFICATION

Resistance(Ω)	Primary Coil	Secondary Coil
Resistance(Ω)	0.62 ± 10% (20°C(68°F))	7.0k ± 15% (20°C(68°F)))

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig.1) Normal waveforms of primary coil at idle.

MONITOR GDS DATA

1.	Connect GDS to Data Link Connector(DLC).

IG “ON”.

3.	Select “DTC” button, and then Press “DTC Status” to check DTC’s information from the DTCs menu.

4.	Read “DTC Status” parameter.

Is parameter displayed “Present fault”?

	▶ Go to “Terminal and Connector inspection” procedure.
	▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.

2.	Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.

Has a problem been found?

	▶ Repair as necessary and go to “Verification of Vehicle Repair” procedure .
	▶ Go to ” Power Circuit Inspection ” procedure.

POWER CIRCUIT INSPECTION

■ Check voltage

1.	IG “OFF” and disconnect Ignition Coil connector.

IG “ON”.

Measure voltage between power terminal of ignition coil harness connector and chassis ground.

Approx. B+

Is the measured voltage within specification ?

	▶ Go to “Control Circuit Inspection” procedure.
	▶ Check fuse connected to ignition coil for open. ▶ Repair open in harness, and go to “Verification of Vehicle Repair” procedure.

CONTROL CIRCUIT INSPECTION

■ Check short to battery in harness

1.	IG “OFF” and disconnect ignition coil connector and ECM connector.

Measure resistance between power and control terminals of ignition coil harness connector.

Infinite

Is the measured resistance within specification?

	▶ Go to “Check short to ground in harness’ as follows.
	▶ Repair short to battery in harness, and go to “Verification of Vehicle Repair” procedure.

■ Check short to ground in harness

1.	IG “OFF” and disconnect ignition coil connector and ECM connector.

Measure resistance between control terminal of ignition coil harness connector and chassis ground.

Infinite

Is the measured resistance within specification?

	▶ Go to “Check open in harness” as follows.
	▶ Repair short to ground in harness, and go to “Verification of Vehicle Repair” procedure.

■ Check open in harness

1.	IG “OFF” and disconnect Ignition Coil connector and ECM connector.

Measure resistance between control terminal of Ignition Coil harness connector and IG Coil #1 control terminal of ECM harness connector.

Below 1Ω

Is the measured resistance within specification?

	▶ Go to “Component Inspection” procedure.
	▶ Repair open in harness

COMPONENT INSPECTION

■ Check Ignition Coil

1.	IG “OFF” and disconnect ignition coil connector.

2.	Measure resistance between power and signal terminals of ignition coil connector.(Measurement “A”)

Measure resistance between power terminal of ignition coil connector and out terminal of secondary ignition coil.(Measurement “B”)

Specification :

Resistance(Ω)	Primary Coil	Secondary Coil
Resistance(Ω)	0.62 ± 10% (20°C(68°F))	7.0k ± 15% (20°C(68°F)))

Is the measured resistance within specification?

▶ Substitute with a known – good ECM and check for proper operation. If the problem is corrected, replace ECM and go to “Verification of Vehicle Repair” procedure.

There is a memory reset function on GDS that can erase optional parts automatically detected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others

▶ Substitute with a known – good Ignition Coil and check for proper operation. If the problem is corrected, replace Ignition Coil

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