Circuit Description
The Secondary Ignition Diagnosis tests the spark plugs, coils and IC Modules. Diagnosis of the Ignition Control (IC) circuits is covered in DTCs P1351 thru P1366. This table requires the following special tools:
| • | J 26792 Spark Tester (ST-125) |
| • | J 36012 spark plug jumper wires |
| • | J 43298 Ignition Module Tester |
Diagnostic Aids
When servicing the ignition system components, use the following recommended procedures:
| • | If a boot remains attached to a coil or spark plug, twist the boot prior to removal. |
| • | Check the boot for a missing or damaged internal spring. |
| • | Do not re-install any component that has visible signs of damage. |
| • | Install the boots onto the coils (until bottomed out). Then install the assembly onto the spark plugs. If this is not possible due to space limitations, just-start the boots onto the spark plugs and then install the coil assembly as straight down onto the plugs as possible. |
| • | Ensure the boots are installed right side up. |
| • | Lift the module beauty cover at the end opposite the module to remove. |
| • | Repair a torn perimeter seal with RTV sealant. |
| • | Adhere to the torque specifications when installing the cassette to the cam cover and the module to the cassette. Refer to Ignition Control Module Replacement and Ignition Coil Replacement for further details. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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If any IC Circuit DTCs are set, perform the DTC table first. If no IC Circuit DTCs are set, check the IC Circuit Status for all cylinders. If an IC Circuit Status indicates anything other than OK (even momentarily), perform the corresponding IC Circuit DTC table as if the DTC were set.
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A misfiring or dead cylinder can sometimes affect the misfire counters for other cylinders. When performing this table, concentrating on the cylinder with the highest level of misfire and correcting the problem, may also correct the other cylinders that indicate misfire. If multiple cylinders are suspected, perform each test on all affected cylinders. An Ignition coil, the boots or spark plugs may fail only when moisture is present. Although difficult to test on this engine, selectively wetting down parts of the system and rechecking for misfire or arcing may uncover a problem with one or more components. If moisture is present in the spark plug/ignition coil cavity of the cam cover, check the perimeter seal for damage. Repair tears in the perimeter seal with RTV sealant. Ensure that the seven cassette mounting bolts are tightened to the specified torque. Refer to Ignition Coil Replacement .
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The J 26792 spark tester (ST 125) presents a more difficult load on the secondary ignition than a normal spark plug. If a miss, stumble, or hesitation is being caused by a spark plug not firing, the spark tester should also not fire.
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A suspected ignition system miss may actually be a fuel system problem. Perform the Fuel System Diagnosis , if it has not yet been performed. An internal engine problem can also cause a driveability concern. Refer to Base Engine Misfire Diagnosis if this is suspected.
If the misfire is gone when running the engine using the J 36012 Spark Plug Jumper wires, and misfire is present when the boots are installed, replace the affected boot.
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An Ignition coil, the boots or spark plugs may fail only when moisture is present. Although difficult to test on this engine, selectively wetting down parts of the system and rechecking for misfire or arcing may uncover an intermittent problem. If moisture is present in the spark plug/ignition coil cavity of the cam cover, check the perimeter seal for damage. Repair tears in the perimeter seal with RTV sealant. Ensure that the seven cassette mounting bolts are tightened to the specified torque. Refer to Ignition Coil Replacement .
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Ensure good DMM contact when measuring spark plug resistance. When manufactured the normal resistance for the spark plug is 3000-8000 ohms. A suspected ignition system miss may actually be a fuel system problem. Perform the Fuel System Diagnosis , if it has not yet been performed. An internal engine problem can also cause a driveability concern. Refer to Base Engine Misfire Diagnosis if this is suspected.
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If the spark plug exhibits unusual signs of damage or deposits, diagnose and correct the root cause of the problem (e.g. excessive detonation, wrong spark plug/incorrect heat range for application, a base engine problem, etc.).
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Be sure to use the correct adaptor harness when connecting the Ignition Module Tester to the LX5 engine. Using an adaptor harness for a different engine application will result in incorrect tool operation.
The green Power LED should come on any time the ignition module tester is connected and the ignition switch is in the run position. This LED simply indicates that the J 43298 is receiving adequate power and ground to perform the test. The Test button is used as an LED check for the four red LEDs. To use this function, connect the tool, turn the ignition switch to run, then momentarily press the Test button. All four red LEDs should come on brightly. The crank the vehicle. If the three red LEDs flash, this confirms proper operation of the primary ignition system (e.g. PCM, wiring, connections, and ICM). The Ignition Module Tester may get hot during actual testing. This is because it is attempting to simulate the load of the ignition coils primary windings.
Only three of the red LEDs are used when testing the LX5 engine. Four LEDs are provided on the tester for eight cylinder applications.
If three LEDs flash, the module output drivers are operating. If one or more LEDs are inoperative (excluding the one unused LED), and no IC Circuit DTCs are set, replace the module.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||||||
2 |
Do any cylinders indicate an excessive amount of misfire? | -- | ||||||||||||||
3 | Is an entire bank of cylinders inoperative? | -- | ||||||||||||||
Check for the following conditions using the scan tool:
Are any IC Circuit DTCs set or does the IC Circuit Status for any cylinder indicate anything other than OK? | -- | Go to the applicable DTC table | ||||||||||||||
The remaining steps are to be performed on the cylinder indicating the highest level of misfire.
Was a problem found? | -- | |||||||||||||||
Does a spark jump the tester gap? | -- | |||||||||||||||
7 | Remove the spark plug on the affected cylinder. Does the spark plug show signs of oil or coolant entering the combustion chamber? | -- | Go to Oil Consumption Diagnosis or Loss of Coolant . | |||||||||||||
8 | Check the spark plug for the following conditions:
Was a problem found? | -- | ||||||||||||||
Did the misfire follow the spark plug? | -- | Refer to Test Description | ||||||||||||||
10 | Important: Remove the Fuel Pump fuse before proceeding. Running or cranking the engine with an Ignition Control module disconnected will cause excessive engine fueling if the fuel pump is not disabled.
Is the frequency within the specified range? | 2 - 20 Hz | ||||||||||||||
11 | Select the Misfire History counters using the scan tool. Do any cylinders indicate a history of misfiring? | -- | System Ok | |||||||||||||
The remaining steps are to be performed on the cylinder indicating the highest level of misfire.
Was a problem found? | -- | |||||||||||||||
13 | Does the spark plug show signs of oil or coolant entering the combustion chamber? | -- | Go to Oil Consumption Diagnosis or Loss of Coolant . | |||||||||||||
14 |
Was a problem found? | -- | ||||||||||||||
Measure the resistance of the affected spark plug. Is the resistance less than the specified value? | 15,000 ohms | The problem is intermittent. Refer to Test Description . | ||||||||||||||
16 |
Does the test light illuminate? | -- | ||||||||||||||
17 | Connect test light J 35616-200 between the Ignition feed circuit and the ground circuit in the Ignition Control module harness. Does the test light illuminate? | -- | ||||||||||||||
18 | Using DMM J 39200 measure the resistance between the ground circuit and the Reference Low circuit in the Ignition Control module harness connector. Does the DMM display the value shown (or lower)? | 5 Ohms | ||||||||||||||
19 | Important: Remove the Fuel Pump fuse before proceeding. Running or cranking the engine with an Ignition Control module disconnected will cause excessive engine fueling if the fuel pump is not disabled.
Is the frequency within the specified range on all circuits tested? | 2 - 20 Hz | ||||||||||||||
20 | Perform repairs as necessary. Is the action complete? | -- | -- | |||||||||||||
21 | Repair the open/high resistance Ignition feed circuit. Is the action complete? | -- | -- | |||||||||||||
22 | Repair the open/high resistance ground circuit. Is the action complete? | -- | -- | |||||||||||||
23 | Repair the open/high resistance Reference Low circuit. Is the action complete? | -- | -- | |||||||||||||
Replace the spark plug. Is the action complete? | -- | -- | ||||||||||||||
Important: Remove the Fuel Pump fuse before proceeding. Running or cranking the engine with an Ignition Control module disconnected will cause excessive engine fueling if the fuel pump is not disabled.
Do three LEDs flash on and off as the engine is cranked? | -- | |||||||||||||||
26 | Check for poor connections/terminal tension between the IC module and the coil assembly. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found and corrected? | -- | ||||||||||||||
27 | Replace the affected coil assembly. Is the action complete? | -- | -- | |||||||||||||
28 | Check for poor connections/terminal tension at the IC module. Refer to Intermittents and Poor Connections Diagnosis . Was a problem found and corrected? | -- | ||||||||||||||
29 | Replace the IC Module. Is the action complete? | -- | -- | |||||||||||||
30 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming Is the action complete? | -- | -- | |||||||||||||
31 |
Do any cylinders indicate an excessive amount of misfire? | -- | System OK | |||||||||||||
32 | Is the misfire indicated on the same cylinder(s) that were just diagnosed? | -- | Go to Fuel System Diagnosis . |
