Component arrangement
| Item name | Spare part catalog number | Description |
| 1 | - | Spark plug |
| 2 | - | Ignition coil |
| 3 | - | Spark plug wire |
| 4 | - | Capacitor |
General information
The 4.0L engine ignition system has one platinum-tipped spark plug per cylinder. Each spark plug is powered by a separate ignition coil. Three ignition coils for each cylinder bank are grouped on the corresponding side of the intake manifold. The ignition coils are directly actuated by the engine control module (ECM).
Power is supplied to the ignition coils via the main relay and fuse in the battery junction box (BJB).
Each ignition coil contains a power transistor that turns on the primary winding. The ECM controls switching using a signal sent to the power transistor. A capacitor connected in parallel with the ignition coil power supplies serves to suppress radio frequency interference. The ECM monitors the operation of the ignition coils using a feedback signal from the power supply circuit of each coil. If a malfunction is detected, the ECM stores a corresponding trouble code.
Depending on the battery voltage and engine speed, the ECM regulates the duration of the primary winding short circuit to ensure that the discharge energy generated in the secondary winding is constant. This ensures good spark formation without overloading the primary winding circuit by current and overheating the ignition coils.
The ECM calculates the ignition timing for the cylinders based on the following data:
- Engine crankshaft speed.
- Position of the camshaft.
- Engine load.
- Coolant temperature.
- Tendency to detonate.
- On vehicles with automatic transmission, the position of the selector is taken into account.
- Idle mode requirements are taken into account.
Ignition control system diagram
NOTE: A = Wired connections
| Item name | Spare part catalog number | Description |
| 1 | - | Battery |
| 2 | - | Fuse link 11E in BJB block |
| 3 | - | Ignition switch |
| 4 | - | Fuse 25P, ignition supply, in central junction box (CJB) |
| 5 | - | 60P fuse, starting power, in CJB |
| 6 | - | ECM |
| 7 | - | Ignition coil 6 |
| 8 | - | Ignition coil 5 |
| 9 | - | Ignition coil 4 |
| 10 | - | Capacitor |
| 11 | - | Ignition coil 1 |
| 12 | - | Ignition coil 2 |
| 13 | - | Ignition coil 3 |
| 14 | - | Fuse 17E in BJB |
| 15 | - | Main relay |
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