Circuit Description
The Secondary Ignition Check tests for faulty spark plugs, plug wires, or IC Module/Coils. This table requires the J 26792 spark tester (ST 125).
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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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.
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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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The companion spark plug shares the same ignition coil with the spark being tested (1-4, 2-5, 6-7, 3-8).
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If the no spark condition follows the suspected coil, that coil is faulty. Otherwise, the ignition module is the cause of no spark. This test could also be performed by substituting a known good coil for the one causing the no spark condition.
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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 Check, if it has not yet been performed.
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If the no spark condition follows the suspected coil, that coil is faulty. This test could also be performed by substituting a known good coil for the one causing the no spark condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 | Key On and connect the scan tool. Are any PCM DTC(s) set? | -- | Go to those DTC(s) first
| |
3 | Perform Injector Balance Check using the scan tool and record the cylinders with no engine speed or idle quality change. Were any non or low functioning cylinders observed? | -- | ||
4 | Were two companion cylinders, 1&4, 2&5, 6&7, or 3&8, observed? | -- | ||
5 | Check affected spark plug wire resistance to ground and resistance end to end. Is spark plug wire shorted to ground or more than the specified value? | 15,000 ohms | ||
6 | Remove affected spark plug. Does spark plug look OK? | -- | ||
Measure resistance or affected spark plug. Does spark plug measure less than the specified value? | 15,000 ohms | |||
Does spark jump tester gap? | -- | Secondary ignition system OK. Go to Fuel System Check | ||
9 |
Does spark jump tester gap? | -- | ||
Does spark jump tester gap? | -- | |||
Switch affected coil with another coil and repeat the Injector Balance Check using the scan tool. Did the fault follow the affected coil? | -- | |||
12 |
Is ignition system arcing externally? | -- | ||
13 |
Does spark jump tester gap? | -- | ||
14 | Check affected spark plug wire resistance to ground and resistance end to end. Is spark plug wire shorted to ground or more than the specified value? | 15,000 ohms | ||
15 | Remove affected spark plugs and check for wear, damage, or fouling. Do both plugs look OK? | -- | ||
Measure resistance of affected spark plugs. Do both spark plugs individually measure less than the specified value? | 15,000 ohms | Secondary ignition system OK. Go to Fuel System Check
| ||
17 |
Does spark jump tester gap on all eight cylinders? | -- | Secondary ignition system OK. Go to Fuel System Check
| |
Switch affected coil with another coil and repeat the spark plug tester test on all four cylinders of switched coils. Did the fault follow the affected coil? | -- | |||
19 |
Is either spark plug wire shorted to ground or more than the specified value? | 15,000 ohms | ||
20 | Remove affected spark plugs and check for wear, damage, or fouling. Do both plugs look OK? | -- | ||
21 | Measure resistance of affected spark plugs. Do both spark plugs individually measure less than the specified value? | 15,000 ohms | ||
22 | Replace the spark plug wire. Spark Plug Wire Harness Replacement in Engine Electrical. Is the action complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
23 | Replace the spark plug. Refer to Spark Plug Replacement in Engine Electrical. Is the action complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
24 | Replace the affected spark plug. Is the action complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
25 | Replace the affected coil. Is the action complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
26 | Replace the IC Module. Is the action complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
27 | Repair the source of arcing. Is the action complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
