Ignition Control - Service Information: Other Dodge Nitro I

IGNITION SYSTEM-3.7L

The ignition system is controlled by the Powertrain Control Module (PCM) on all engines.

This engine uses a separate ignition coil for each cylinder. The one-piece coil bolts directly to the cylinder head. Rubber boots seal the secondary terminal ends of the coils to the top of all 6 spark plugs. A separate electrical connector is used for each coil.

Because of coil design, spark plug cables (secondary cables) are not used. A distributor is not used with the 3.7L engine.

Two knock sensors (one for each cylinder bank) are used to help control spark knock.

The Auto Shutdown (ASD) relay provides battery voltage to each ignition coil.

The ignition system consists of

1. 6 Spark Plugs
2. 6 Separate Ignition Coils
3. 2 Knock Sensors
4. Powertrain Control Module (PCM)
5. Also to be considered part of the ignition system are certain inputs from the Crankshaft Position, Camshaft Position, 2 knock and MAP Sensors

IGNITION COIL RESISTANCE - 3.7L V-6

IGNITION TIMING

Ignition timing is not adjustable on any engine.

SPARK PLUGS

CAMSHAFT POSITION SENSOR - 3.7L

1. Clean out machined hole in cylinder head.
2. Apply a small amount of engine oil to sensor o-ring.
3. Install sensor (3) into cylinder head with a slight rocking and twisting action. CAUTION: Before tightening sensor mounting bolt (2), be sure sensor is completely flush to cylinder head. If sensor is not flush, damage to sensor mounting tang may result.
4. Install mounting bolt (2) and tighten to 12 N.m (106 in.lbs).
5. Connect electrical connector to sensor.

COIL-IGNITION - 3.7L

1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
2. Check condition of coil O-ring (2) and replace as necessary. To aid in coil installation, apply silicone to coil o-ring (2).
3. Position ignition coil (1) into cylinder head opening and push onto spark plug. Do this while guiding coil base over mounting stud.
4. Install coil mounting stud nut (2). Refer to «SPECIFICATIONS»(ref-306179-S05120182152008120900000) .
5. Connect electrical connector to coil by snapping into position.
6. If necessary, install throttle body air tube.

COIL-IGNITION - 4.0L

1. Install ignition coil (3) into cylinder head.
2. Install and tighten coil mounting bolt (2). Refer to «SPECIFICATIONS»(ref-306179-S05120182152008120900000) .
3. Connect electrical connector (1) and lock.
4. Install upper half of intake manifold. Refer to «INSTALLATION»(ref-306142-S30306992222008120900000) - 3.7L or «INSTALLATION»(ref-306143-S05495232132008120900000) - 4.0L ).
5. Connect negative battery cable.
6. Install engine cover.

Each individual spark plug is located under each ignition coil. Each individual ignition coil must be removed to gain access to each spark plug. See REMOVAL .

1. Remove necessary air filter tubing at throttle body.
2. Prior to removing ignition coil, spray compressed air around coil base at cylinder head.
3. Prior to removing spark plug, spray compressed air into cylinder head opening. This will help prevent foreign material from entering combustion chamber.
4. Remove spark plug from cylinder head using a quality socket with a rubber or foam insert. Also check condition of ignition coil O-ring and replace as necessary.
5. Inspect spark plug condition.

IGNITION SWITCH

Vehicles equipped with an automatic transmission and a steering column mounted shifter: an interlock device is located within the shift cable. This interlock device is used to lock the transmission shifter in the PARK position when the key cylinder is in any position and the brake pedal is not depressed.

The ignition key must be in the key cylinder for cylinder removal. The key cylinder must be removed first before installing ignition switch.

Scheme 26

Scheme 27

Scheme 28

Scheme 29

1. Before installing ignition switch, rotate the slot in the switch to the ON position. 1 - Ignition Switch 2 - Ignition Switch Mounting Screws
2. Connect the electrical connector to rear of the ignition switch. Make sure that locking tabs are fully seated into wiring connector.
3. Position switch (1) to column and install the mounting screws (2). Tighten screw to 3 N.m (26 in. lbs.). 1 - IGNITION SWITCH 2 - TILT LEVER MECHANISM
4. Install the tilt lever bracket (2) mounting screws. Tighten screws to 4.5 N.m (40 in. lbs.). 1 - Ignition Switch Mounting Screws 2 - Non-Tilt Mounting Bracket Screws
5. If the column is non-tilt install the bracket. Tighten screws (2) to 4.5 N.m (40 in. lbs.). (Scheme 28)1 - KEY CYLINDER 2 - GEAR SHIFT LEVER 3 - MOUNTING HOLES 4 - STEERING COLUMN 5 - IGNITION SWITCH
6. Position the wire retainer into the tilt lever bracket.
7. Reconnect the lower clockspring connectors.
8. Install the key cylinder (1)
9. Install steering column upper and lower shrouds.
10. Enable the airbag system. Refer to «INSTALLATION»(ref-306149-S13336661352008120900000).

KEY-IN IGNITION SWITCH

The key-in ignition switch is integral to the ignition switch, which is mounted on the left side of the steering column. It closes a path to ground for the Central Timer Module (CTM) when the ignition key is inserted in the ignition key cylinder and the driver door ajar switch is closed (driver door is open). The key-in ignition switch opens the ground path when the key is removed from the ignition key cylinder. The ground path is also opened when the driver door ajar switch is open (driver door is closed).

The key-in ignition switch cannot be repaired and, if faulty or damaged, the entire ignition switch must be replaced, refer to REMOVAL .

GLOW PLUG SYSTEM

1. Measure the electrical resistance of each glow plug while it is still installed in the cylinder head. Resistance should be less than 0.8 ohm; between the electrical connector point on the glow plug and the cylinder head. The ground contact on the DVOM must be as close as possible to the point where the glow plug contacts the cylinder head to avoid erratic resistance measurements.
2. If the resistance is out of tolerance, remove the glow plug from the cylinder head and check the resistance again.
3. Use the actuator test function of the scan tool to test the glow plug module and glow plug lamp. The glow plug module's on-board diagnostic tests will automatically check the electrical condition of the entire glow plug system.
4. After the scan tool glow plug actuator test function is complete, if MIL is OFF and no glow plug DTCs are present, testing is complete and the engine can be started.
5. If MIL is still ON, check the harness connectors of glow plugs, repair any loose or damaged connections, and run the glow plug actuator test again.
6. If MIL is still ON and glow plug DTCs are present, refer to appropriate Engine ELECTRICAL DIAGNOSTICS article , and follow the diagnostic test(s) related to the active or stored DTCs.

Scheme 30

The four glow plugs (1) are attached to cylinder head below fuel rail.

Scheme 31

1. Disconnect negative battery cable.
2. Remove fuel rail and high-pressure fuel lines.
3. Disconnect glow plug wiring harness (2) at all four glow plugs (1).
4. Use a socket to loosen glow plug(s) (1), (2), (3) or (4). After loosening, attach a flexible tool such as a rubber hose to remove glow plug from cylinder head.