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Ignition Coil Primary Circuit Malfunction

DTC P0350 DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0350 IGNITION COIL PRIMARY CIRCUIT MALFUNCTION
DETECTION CONDITION 
  • P0350 indicates that the PCM did not receive a valid Ignition Diagnostic Monitor (IDM) pulse signal, which indicates that the primary side of the coil has failed, from the ignition module (integrated in the PCM) which is caused by an ignition coil primary/secondary circuit malfunction.
POSSIBLE CAUSE 
  • Open or short in ignition START/RUN circuit.
  • Open coil driver circuit.
  • Coil driver circuit shorted to ground.
  • Damaged coil.
  • Coil driver circuit shorted to VPWR.
HINT  Ignition Coil Description 
  • Coil packs come in a tower configuration with two adjacent coil towers sharing a common coil (and called a matched pair).
    • For 4 cylinder applications, the matched pairs are 1 and 4, and 2 and 3.
    • For 6 cylinder applications, the matched pairs are 1 and 5, 2 and 6, and 3 and 4.
  • When the coil is fired by the PCM, spark is delivered to a matched pair of towers to their respective spark plugs.
    • The spark plugs are fired simultaneously and are paired so that as one fires on the compression stroke, the other spark plug fires on the exhaust stroke.
    • The next time the coil is fired, the situation is reversed with the next pair of spark plugs being fired according to the engine firing order.
G03988127Courtesy of MAZDA MOTORS CORP.
G03988128Courtesy of MAZDA MOTORS CORP.
G03988129Courtesy of MAZDA MOTORS CORP.
DTC P0350 INSPECTION

STEP INSPECTION ACTION
1
  • Was PCM Quick Test performed? 
 Yes Go to next step.
No Perform PCM Quick Test.
2 VISUAL INSPECTION
  • Visually inspect the engine compartment to make sure all vacuum hoses and spark plug wires are properly routed and securely connected.
  • Examine all wiring harnesses and connectors for damaged, burned or overheated insulation and loose or broken conditions.
  • Make certain the battery is fully charged.
  • All accessories must be off during diagnosis.
  • Is a problem indicated? 
 Yes Repair as necessary.
Go to step 12.
No For ignition coil application using engine analyzer:
Go to next step.
For ignition coil application not using engine analyzer:
Go to step 6.
3 CONNECT ENGINE ANALYZER
  • Obtain Engine Analyzer to diagnose concerns in the secondary side of the ignition system.
    NOTE: In order for the diagnostic procedures to provide accurate results, it is essential that the calibration of the engine analyzer be maintained. Refer to the equipment manual for the procedure to calibrate the engine analyzer. If the equipment manual is not available, an estimate of the calibration can be made by connecting a Spark Tester to a properly operating ignition system and measuring the firing voltage of the spark tester only. The spark tester firing voltage should be approximately 28KV.
  • Is the engine analyzer connected? 
 Yes Go to next step.
No Repeat this step.
4 CHECK FOR IGNITION PATTERN
  • Observe pattern on scope while cranking engine. Refer to figure A in the illustration at the beginning of this test.
  • Is the pattern flat which indicates no spark on all cylinders? 
 Yes IGN START/ON (RUN) circuit concern. Key OFF. Check condition of fuse 19 in IP fuse panel. If OK, repair open circuit. If fuse/fuse link is damaged, check IGN START/ON (RUN) circuit for short to ground. Repair as necessary. Go to step 12.
No Go to next step.
5 CHECK FOR NORMAL IGNITION PATTERN
NOTE: Spark plugs are fired up to four strikes per firing. Multi-strike operating mode is dependent on the PCM calibration and is limited to less than 2000 rpm. Above 2000 rpm, spark plugs are fired once per firing.
  • Key ON, Engine Running (KOER).
  • Check spark plug firing voltage average and evenness of patterns. Refer to figure B in the illustration at the beginning of this test.
  • Are all patterns even and is the average value of spark plug firing voltage 20KV or greater with evenness of spark plug firing voltage 8KV or less? 
 Yes If you were directed to this Pinpoint Test from Diagnostic Index, return to DIAGNOSTIC INDEX .
If you were directed to this Pinpoint Test from Misfire Detection Monitor step 4, return to MISFIRE DETECTION MONITOR  step 5.
If you were directed to this Pinpoint Test from Test 16: No Start step 6, return to TEST 16: NO START step 7.
All others, see TEST 4: INTERMITTENT .
No Go to next step.
6 CHECK PATTERN ON SCOPE
  • Observe pattern on scope and look for anything unusual. Refer to figures C-G in the illustration at the beginning of this test for unusual signal patterns.
  • Does pattern appear normal? 
 Yes Go to next step.
No Inspect spark plug wires and spark plugs. Measure resistance of spark plugs. Replace if greater than 7000 ohms per foot (30.5 cm).
Check spark plug gaps. Adjust if necessary. Measure resistance of spark plugs. Replace if lower than 2000 or higher than 20000 ohms.
Go to step 11.
7 DTC P0301 THROUGH P0306: MISFIRE ON CYLINDERS 1 THROUGH 6
  • Are any of the above listed DTCs present? 
 Yes Go to next step.
No Go to step 9.
8 CHECK FOR SPARK AT CYLINDER(S) INDICATED BY DTC(S)
  • Disable inertia fuel shutoff switch.
  • Connect a Spark Tester and check for spark at suspect cylinder while cranking engine.
  • Is the bluish-white spark present? 
 Yes Key OFF. Go to step 10.
No Key OFF.
Inspect spark plugs at missing cylinders. Measure resistance of spark plugs. Replace spark plug if lower than 2000 or higher than 20000 ohms.
Go to step 12.
9 CHECK FOR SPARK AT ALL CYLINDERS
  • Disable inertia fuel shutoff switch.
  • Using a Spark Tester check for spark at each cylinder while cranking engine.
  • Is the bluish-white spark consistent between all cylinders? 
 Yes Key OFF.
Go to next step.
No Key OFF.
Measure resistance of spark plugs. Replace spark plug if lower than 2000 or higher than 20000 ohms.
Go to step 12.
10 CHECK SPARK PLUGS
  • Remove and check spark plugs for damage, wear, carbon deposits and proper plug gap.
  • Are plugs OK? 
 Yes Go to next step.
No Repair plugs. Adjust gap or replace if necessary.
Go to step 12.
11 CHECK SPARK PLUG RESISTANCE
  • Measure spark plug resistance.
  • Is resistance between 2000 and 20000 ohms? 
 Yes If you were directed to this Pinpoint Test from Diagnostic Index, return to DIAGNOSTIC INDEX .
If you were directed to this Pinpoint Test from Misfire Detection Monitor step 4, return to MISFIRE DETECTION MONITOR  step 5.
If you were directed to this Pinpoint Test from Test 16: No Start step 6, return to TEST 16: NO START step 6.
 
All others, see TEST 4: INTERMITTENT .
No Replace spark plugs.
Go to step 12.
12 DRIVE CYCLE
  • Make sure to reconnect all disconnected connectors.
  • Clear DTCs from PCM memory using NGS tester generic OBD-II function.
  • Perform Misfire Monitor Drive Cycle.

    See DRIVE CYCLES .

  • Retrieve pending code.
  • Is same DTC present? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to next step.
No Go to next step.
13 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Perform PCM Quick Test.
  • Is any DTC present? 
 Yes Go to applicable DTC inspection.
No Troubleshooting complete.
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