Diagnostic Aids
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Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:
- Ignition coils.
- Ignition coils harness.
- Powertrain Control Module (PCM).
NOTE:
Performing TEST JB and using test results can help determine which coil is not firing.
- 1) Determine Which Coil Is Not Firing
Using engine analyzer, ignition coil-to-cylinder correlation chart, determine which coil is not firing. See Fig 1. Record cylinder, coil and PCM connector pin number and go to next step. - 2) DTC P0351, P0356 & P0357: Crankshaft Position (CKP) Sensor Failure
If DTC P0351, P0356 or P0357 is present, go to next step. If DTC P0351, P0356 or P0357 is not present, go to step 4). - 3) DTC P0351, P0356 & P0357: Check Crankshaft Position (CKP) Sensor
Disconnect CKP sensor connector. Measure resistance between CKP sensor terminals. If resistance is 290-390 ohms, go to next step. If resistance is not 290-390 ohms, replace CKP sensor. - 4) Check Functionality Of Suspect Coil Driver Circuit
Disconnect suspect coil that was determined in step 1) . Connect a test light between IGN START/RUN terminal and suspect CD circuit terminal at coil wiring harness connector. See Fig 2 or Fig 3 . Disconnect Inertia Fuel Shutoff (IFS) switch to disable fuel pump. Observe test light and crank engine. If test light blinks consistently, turn ignition off and go to next step. If test light does not blink consistently, go to step 6). - 5) Check Suspect Coil
Turn ignition off. Remove suspect coil from spark plug. Install Spark Tester (D81P-6666-A) to suspect coil. Reconnect coil connector. Observe spark tester and crank engine. If spark is not present, replace coil. Inspect spark plug and replace as necessary. If spark is present, check spark plug. Replace as necessary and retest. If spark plug is okay, no fault is present at this time. Go to TEST Z . - 6) Check IGN START/RUN Voltage To Suspect Coil
Turn ignition on. Measure voltage between IGN START/RUN terminal at suspect coil wiring harness connector and chassis ground. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, check condition of related fuses/fuse links. If fuse/fuse links are blown, check for short to ground in IGN START/RUN circuit. Repair as necessary. If fuse/fuse links are okay, repair open in IGN START/RUN circuit. - 7) Check For Open In Suspect CD Circuit
Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance of suspect CD circuit between PCM connector and appropriate coil wiring harness connector. See Fig 2 or Fig 3 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in CD circuit. - 8) Check Suspect CD Circuit For Short To Power
Turn ignition on. Measure voltage of suspect CD circuit between appropriate PCM connector pin and negative battery terminal. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair CD circuit short to power. - 9) Check Suspect CD Circuit For Short To Ground
Turn ignition off. Disconnect scan tool from DLC. Measure resistance of suspect CD circuit between appropriate PCM connector pin and chassis ground. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in CD circuit. If symptom still exists after repair is complete, go to step 11). - 10) Check For Intermittent Fault
Connect DVOM between CD circuit pin at PCM connector and CD terminal at coil wiring harness connector. Observe DVOM for indication of fault while wiggling and bending suspect CD circuit. Start at coil connector and work toward PCM connector. Fault will be indicated by sudden change in DVOM resistance. If a fault is indicated, isolate fault and repair as necessary. If no fault is indicated, replace PCM. - 11) Check Suspect Coil
Turn ignition off. Disconnect Inertia Fuel Shutoff (IFS) switch to disable fuel pump. Remove suspect coil. Connect Spark Tester (D81P-6666-A) to suspect coil. Observe spark tester and crank engine. If spark is present, inspect spark plug and replace as necessary. If spark plug is okay, check for intermittents. See TEST Z . If spark is not present, replace coil. Inspect spark plug and replace as necessary. If spark plug is okay, testing is complete.