For 1990-2009 cars
Engine Controls Components
Cell 21: Ignition Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

#### 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.

1. Ensure good DMM contact when measuring spark plug resistance. When manufactured the normal resistance for the spark plug is 900-2500 ohms but resistance growth up to 10K ohms is considered normal.

2. 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.

3. The companion spark plug shares the same ignition coil with the spark being tested (1-4, 2-5, 6-7, 3-8).

4. 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.

5. Ensure good DMM contact when measuring spark plug resistance. When manufactured the normal resistance for the spark plug is 900-2500 ohms but resistance growth up to 10K ohms is considered normal. A suspected ignition system miss may actually be a fuel system problem. Perform the Fuel System Diagnosis, if it has not yet been performed.

6. 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.

#### Secondary Ignition Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain OBD System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Key on and connect the scan tool. Are any PCM DTC(s) set? | -- | Go to applicable DTCs | Go to Step 3
3 | Perform Fuel Injector Balance Test using the scan tool and note cylinders with no engine speed or idle quality change. Were any cylinders noted? | -- | Go to Step 4 | Go to Step 17
4 | Were two companion cylinders noted? | -- | Go to Step 10 | Go to Step 5
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? | 7000 ohms (7K ohms) | Go to Step 22 | Go to Step 6
6 | Remove affected spark plug. Does spark look OK? | -- | Go to Step 7 | Go to Step 23
7 | Measure resistance or affected spark plug. Does spark plug measure less than the specified value? | 10,000 ohms (10K ohms) | Go to Step 8 | Go to Step 23
8 |

1. Ground companion spark plug lead for affected cylinder.
2. Install spark tester J 26792.
3. Crank engine and note spark plug tester.

Does spark jump tester gap?

--

Go to Fuel System Diagnosis

Go to Step 9

9 |

1. Ground affected spark plug lead.
2. Install spark tester J 26792 on companion cylinder to the cylinder that was affected.
3. Crank engine and note spark plug tester.

Does spark jump tester gap?

--

Go to Step 25

Go to Step 26

10 |

1. Ground one affected spark plug lead.
2. Install spark tester J 26792 on companion cylinder of the grounded cylinder.
3. Crank engine and note spark plug tester.

Does spark jump tester gap?

--

Go to Step 12

Go to Step 11

11 | Switch affected coil with another coil and repeat the Fuel Injector Balance Test . Did the fault follow the affected coil? | -- | Go to Step 25 | Go to Step 26
12 |

1. Reinstall all spark plugs and wires.
2. Start engine and inspect for visible/audible arcing.

Is ignition system arcing externally?

--

Go to Step 27

Go to Step 13

13 |

1. Ground other affected spark plug lead.
2. Install spark tester J 26792 on companion cylinder of the grounded cylinder.
3. Crank engine and note spark plug tester.

Does spark jump tester gap?

--

Go to Step 14

Go to Step 25

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? | 7000 ohms (7K ohms) | Go to Step 22 | Go to Step 15
15 | Remove affected spark plugs and check for wear, damage, or fouling. Do both plugs look OK? | -- | Go to Step 16 | Go to Step 24
16 | Measure resistance of affected spark plugs. Do both spark plugs individually measure less than the specified value? | 10,000 ohms (10K ohms) | Go to Fuel System Diagnosis | Go to Step 24
17 |

1. Install spark tester J 26792 on one spark plug wire and ground its companion cylinder.
2. Note spark plug tester with engine idling.
3. Repeat above test for each cylinder, being sure to ground the companion cylinders.

Does spark jump tester gap on all eight cylinders?

--

Go to Fuel System Diagnosis

Go to Step 18

18 | 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? | -- | Go to Step 25 | Go to Step 19
19 |

1. Switch coils back.
2. Check affected spark plug wire resistance to ground and resistance end to end.

Is either spark plug wire shorted to ground or more than the specified value?

7000 ohms (7K ohms)

Go to Step 22

Go to Step 20

20 | Remove affected spark plugs and check for wear, damage, or fouling. Do both plugs look OK? | -- | Go to Step 21 | Go to Step 24
21 | Measure resistance of affected spark plugs. Do both spark plugs individually measure less than the specified value? | 10,000 ohms (10K ohms) | Go to Step 26 | Go to Step 24
22 | Replace the spark plug wire. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 28 | --
23 | Replace the spark plug. Refer to Spark Plug Replacement in Engine Electrical. Is the action complete? | -- | Go to Step 28 | --
24 | Replace the affected spark plug. Refer to Spark Plug Replacement in Engine Electrical. Is the action complete? | -- | Go to Step 28 | --
25 | Replace the affected coil. Refer to Ignition Coil(s) Replacement . Is the action complete? | -- | Go to Step 28 | --
26 | Replace the IC Module. Refer to Ignition Control Module Replacement . Is the action complete? | -- | Go to Step 28 | --
27 | Repair the source of arcing. Is the action complete? | -- | Go to Step 28 | --
28 | Operate the vehicle within the conditions as noted by the customer. Was a driveability complaint noted? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check | System OK