Secondary Ignition Diagnosis

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.
7. Ensure good DMM contact when measuring spark plug resistance. When manufactured the normal resistance for the spark plug is 3000-8000 ohms.
8. 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 tire.
10. The companion spark plug shares the same ignition coil with the spark being tested (1-4, 2-5, 6-7, 3-8).
11. 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.
16. Ensure good DMM contact when measuring spark plug resistance. When manufactured the normal resistance for the spark plug is 300 - 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.
18. 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. Component Tests and General Diagnostics