Ignition Coil Resistance
- Coil is designed to operate with an external ballast resistor. When testing ignition coil for output and resistance, also make ballast resistor tests. See Figure. Inspect coil for external cracks and arcing at same time.
- To check coil primary resistance, isolate coil from rest of system. Connect ohmmeter leads to positive and negative primary terminals. To check secondary resistance, connect ohmmeter leads to coil negative terminal and coil tower.
- If resistance readings are not to specifications, replace ignition coil.
Resistance Specifications
| Application | Ohms@70-80°F | |
|---|---|---|
| Primary Resistance | ||
| Prestolite | 1.60-1.79 | |
| Essex | 1.34-1.55 | |
| Secondary Resistance | ||
| Prestolite | 9400-11, 700 | |
| Essex | 9000-12, 200 | |
| Single Ballast Resistor | ||
| Resistor Resistance | 1.12-1.38 | |