Ignition System - Service Information: Other Dodge Dakota III

3.7L V-6 ENGINE

The 3.7L V-6 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, Throttle Position, 2 knock and MAP Sensors

4.7L V-8 ENGINE

The 4.7L V-8 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 8 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 4.7L 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. 8 Spark Plugs
2. 8 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, Throttle Position, 2 knock and MAP Sensors

ENGINE FIRING ORDER - 3.7L V-6

1 - 6 - 5 - 4 - 3 - 2

Scheme 12

SPARK PLUG CABLE RESISTANCE

SPARK PLUGS

IGNITION COIL RESISTANCE - 3.7L V-6

IGNITION COIL RESISTANCE - 4.7L V-8

IGNITION TIMING

Ignition timing is not adjustable on any engine.

PCM OUTPUT

The ASD relay supplies battery voltage (12+ volts) to the fuel injectors and ignition coil(s). With certain emissions packages it also supplies 12-volts to the oxygen sensor heating elements.

The ground circuit for the coil within the ASD relay is controlled by the Powertrain Control Module (PCM). The PCM operates the ASD relay by switching its ground circuit on and off.

The ASD relay will be shut-down, meaning the 12-volt power supply to the ASD relay will be de-activated by the PCM if

1. the ignition key is left in the ON position. This is if the engine has not been running for approximately 1.8 seconds.
2. there is a crankshaft position sensor signal to the PCM that is lower than pre-determined values.

ASD SENSE - PCM INPUT

A 12 volt signal at this input indicates to the PCM that the ASD has been activated. The relay is used to connect the oxygen sensor heater element, ignition coil and fuel injectors to 12 volt + power supply.

This input is used only to sense that the ASD relay is energized. If the Powertrain Control Module (PCM) does not see 12 volts at this input when the ASD should be activated, it will set a Diagnostic Trouble Code (DTC).

3.7L V-6

The Camshaft Position Sensor (CMP) on the 3.7L 6-cylinder engine is bolted to the right-front side of the right cylinder head.

4.7L V-8

The Camshaft Position Sensor (CMP) on the 4.7L V-8 engine is bolted to the right-front side of the right cylinder head.

Scheme 13

The Camshaft Position Sensor (CMP) sensor on the 3.7L V-6 engine (3) contains a hall effect device referred to as a sync signal generator. A rotating target wheel (tone wheel) for the CMP is located (4) at the front of the camshaft for the right cylinder head (2). This sync signal generator detects notches (1) located on a tone wheel. As the tone wheel rotates, the notches pass through the sync signal generator. The signal from the CMP sensor is used in conjunction with the Crankshaft Position Sensor (CKP) to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

When the leading edge of the tone wheel notch enters the tip of the CMP, the interruption of magnetic field causes the voltage to switch high, resulting in a sync signal of approximately 5 volts.

When the trailing edge of the tone wheel notch leaves then tip of the CMP, the change of the magnetic field causes the sync signal voltage to switch low to 0 volts.

Scheme 14

The CMP sensor on the 4.7L engine contains a hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects notches located on a tone wheel. The tone wheel (4) is located at the front of the camshaft for the right cylinder head (2). As the tone wheel rotates, the notches (1) pass through the sync signal generator. The pattern of the notches (viewed counterclockwise from front of engine) is: 1 notch, 2 notches, 3 notches, 3 notches, 2 notches 1 notch, 3 notches and 1 notch. The signal from the CMP sensor is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

Scheme 15

The Camshaft Position Sensor (CMP) on the 3.7L V-6 engine (3) is bolted to the front/top of the right cylinder head (1).

1. Disconnect electrical connector at CMP sensor.
2. Remove sensor mounting bolt (2).
3. Carefully twist sensor from cylinder head.
4. Check condition of sensor o-ring.

Scheme 16

The Camshaft Position Sensor (CMP) on the 4.7L V-8 engine (2) is bolted to the front/top of the right cylinder head (1).

1. Raise and support vehicle.
2. Disconnect electrical connector (4) at CMP sensor.
3. Remove sensor mounting bolt (3).
4. Carefully twist sensor from cylinder head.
5. Check condition of sensor o-ring.

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. Refer to «SPECIFICATIONS - TORQUE - IGNITION»(ref-247622-S29114618182007020100000) .
5. Connect electrical connector to sensor.

1. Clean out machined hole in cylinder head.
2. Apply a small amount of engine oil to sensor o-ring.
3. Install sensor (2) into cylinder head with a slight rocking action. Do not twist sensor into position as damage to o-ring may result. CAUTION: Before tightening sensor mounting bolt (3), 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 (3) and tighten. Refer to «SPECIFICATIONS - TORQUE - IGNITION»(ref-247622-S29114618182007020100000) .
5. Connect electrical connector (4) to sensor.

Scheme 17

The 3.7L V-6 engine uses 6 dedicated, and individually fired coil for each spark plug (2).

Scheme 18

Each coil (1) is mounted directly into the cylinder head and onto the top of each spark plug.

Scheme 19

The 4.7L V-8 engine uses 8 dedicated, and individually fired coil (1) for each spark plug. Each coil is mounted directly to the top of each spark plug.

Battery voltage is supplied to the 6 individual ignition coils from the ASD relay. The Powertrain Control Module (PCM) opens and closes each ignition coil ground circuit at a determined time for ignition coil operation.

Base ignition timing is not adjustable. By controlling the coil ground circuit, the PCM is able to set the base timing and adjust the ignition timing advance. This is done to meet changing engine operating conditions.

The ignition coil is not oil filled. The windings are embedded in an epoxy compound. This provides heat and vibration resistance that allows the ignition coil to be mounted on the engine.

Because of coil design, spark plug cables (secondary cables) are not used with the 3.7L V-6 engine.

Battery voltage is supplied to the 8 individual ignition coils from the ASD relay. The Powertrain Control Module (PCM) opens and closes each ignition coil ground circuit at a determined time for ignition coil operation.

Base ignition timing is not adjustable. By controlling the coil ground circuit, the PCM is able to set the base timing and adjust the ignition timing advance. This is done to meet changing engine operating conditions.

The ignition coil is not oil filled. The windings are embedded in an epoxy compound. This provides heat and vibration resistance that allows the ignition coil to be mounted on the engine.

Because of coil design, spark plug cables (secondary cables) are not used with the 4.7L V-8 engine.

An individual ignition coil is used for each spark plug (2). The coil fits into machined holes in the cylinder head. A mounting stud/nut secures each coil to the top of the intake manifold. The bottom of the coil is equipped with a rubber boot to seal the spark plug to the coil. Inside each rubber boot is a spring. The spring is used for a mechanical contact between the coil and the top of the spark plug. These rubber boots and springs are a permanent part of the coil and are not serviced separately. An O-ring (1) is used to seal the coil at the opening into the cylinder head.

1. Depending on which coil is being removed, the throttle body air intake tube or intake box may need to be removed to gain access to coil.
2. Disconnect electrical connector from coil by pushing downward on release lock on top of connector and pull connector from coil.
3. Clean area at base of coil with compressed air before removal.
4. Remove coil mounting nut (2) from mounting stud.
5. Carefully pull up coil from cylinder head opening with a slight twisting action.
6. Remove coil from vehicle.

An individual ignition coil (1) is used for each spark plug. The coil fits into machined holes in the cylinder head. A mounting stud/nut (3) secures each coil to the top of the intake manifold. The bottom of the coil is equipped with a rubber boot to seal the spark plug to the coil. Inside each rubber boot is a spring. The spring is used for a mechanical contact between the coil and the top of the spark plug. These rubber boots and springs are a permanent part of the coil and are not serviced separately. An o-ring is used to seal the coil at the opening into the cylinder head.

1. Depending on which coil is being removed, the throttle body air intake tube or intake box may need to be removed to gain access to coil.
2. Disconnect electrical connector (2) from coil by pushing downward on release lock on top of connector and pull connector from coil.
3. Clean area at base of coil with compressed air before removal.
4. Remove coil mounting nut (3) from mounting stud.
5. Carefully pull up coil from cylinder head opening with a slight twisting action.
6. Remove coil from vehicle.

1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
2. Check condition of coil o-ring and replace as necessary. To aid in coil installation, apply silicone to coil o-ring.
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 - TORQUE - IGNITION»(ref-247622-S29114618182007020100000) .
5. Connect electrical connector to coil by snapping into position.
6. If necessary, install throttle body air tube.

1. Using compressed air, blow out any dirt or contaminants from around top of spark plug.
2. Check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil O-ring.
3. Position ignition coil into cylinder head opening and push onto spark plug. Do this while guiding coil base over mounting stud.
4. Install coil mounting stud nut (3). Refer to «SPECIFICATIONS - TORQUE - IGNITION»(ref-247622-S29114618182007020100000) .
5. Connect electrical connector (2) to coil by snapping into position.
6. If necessary, install throttle body air tube.

3.7L V-6 / 4.7L V-8 Engines

Two knock sensors are used; one for each cylinder bank. When the knock sensor detects a knock in one of the cylinders on the corresponding bank, it sends an input signal to the Powertrain Control Module (PCM). In response, the PCM retards ignition timing for all cylinders by a scheduled amount.

Knock sensors contain a piezoelectric material which constantly vibrates and sends an input voltage (signal) to the PCM while the engine operates. As the intensity of the crystal's vibration increases, the knock sensor output voltage also increases.

The voltage signal produced by the knock sensor increases with the amplitude of vibration. The PCM receives the knock sensor voltage signal as an input. If the signal rises above a predetermined level, the PCM will store that value in memory and retard ignition timing to reduce engine knock. If the knock sensor voltage exceeds a preset value, the PCM retards ignition timing for all cylinders. It is not a selective cylinder retard.

The PCM ignores knock sensor input during engine idle conditions. Once the engine speed exceeds a specified value, knock retard is allowed.

Knock retard uses its own short term and long term memory program.

Long term memory stores previous detonation information in its battery-backed RAM. The maximum authority that long term memory has over timing retard can be calibrated.

Short term memory is allowed to retard timing up to a preset amount under all operating conditions (as long as RPM is above the minimum RPM) except at Wide Open Throttle (WOT). The PCM, using short term memory, can respond quickly to retard timing when engine knock is detected. Short term memory is lost any time the ignition key is turned off.

Note. Over or under tightening the sensor mounting bolts will affect knock sensor performance, possibly causing improper spark control. Always use the specified torque when installing the knock sensors.

Scheme 20

The 2 knock sensors are bolted into the cylinder block under the intake manifold (1) and (2).

Note. The left sensor is identified by an identification tag (LEFT). It is also identified by a larger bolt head. The Powertrain Control Module (PCM) must have and know the correct sensor left/right positions. Do not mix the sensor locations.

1. Disconnect knock sensor dual pigtail harness from engine wiring harness. This connection is made near rear of engine.
2. Remove intake manifold. Refer to appropriate Engine SERVICE INFORMATION article.
3. Remove sensor mounting bolts (2). Note foam strip on bolt threads. This foam is used only to retain the bolts to sensors for plant assembly. It is not used as a sealant. Do not apply any adhesive, sealant or thread locking compound to these bolts.
4. Remove sensors from engine.

Scheme 21

The two knock sensors (1) are bolted into the cylinder block under the intake manifold (3).

Note. The left sensor is identified by an identification tag (LEFT). It is also identified by a larger bolt head. The Powertrain Control Module (PCM) must have and know the correct sensor left/right positions. Do not mix the sensor locations.

1. Disconnect knock sensor dual pigtail harness from engine wiring harness. This connection is made near rear of engine.
2. Remove intake manifold. Refer to appropriate Engine SERVICE INFORMATION article.
3. Remove sensor mounting bolts (2). Note foam strip on bolt threads. This foam is used only to retain the bolts to sensors for plant assembly. It is not used as a sealant. Do not apply any adhesive, sealant or thread locking compound to these bolts.
4. Remove sensors from engine.

3.7L V-6 / 4.7L V-8

Note. The left sensor is identified by an identification tag (LEFT). It is also identified by a larger bolt head. The Powertrain Control Module (PCM) must have and know the correct sensor left/right positions. Do not mix the sensor locations.

1. Thoroughly clean knock sensor mounting holes.
2. Install sensors (1) into cylinder block. NOTE: Over or under tightening the sensor mounting bolts (2) will affect knock sensor performance, possibly causing improper spark control. Always use the specified torque when installing the knock sensors. The torque for the knock senor bolt is relatively light for an 8 mm bolt. NOTE: Note foam strip on bolt threads. This foam is used only to retain the bolts to sensors for plant assembly. It is not used as a sealant. Do not apply any adhesive, sealant or thread locking compound to these bolts.
3. Install and tighten mounting bolts. Refer to «SPECIFICATIONS - TORQUE - IGNITION»(ref-247622-S29114618182007020100000) .
4. Install intake manifold. Refer to appropriate Engine SERVICE INFORMATION article.
5. Connect knock sensor wiring harness to engine harness at rear of intake manifold.

Each individual spark plug is located under each ignition coil. Each individual ignition coil must be removed to gain access to each spark plug. Refer to Ignition Coil REMOVAL / INSTALLATION .

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.

Each individual spark plug is located under each ignition coil. Each individual ignition coil must be removed to gain access to each spark plug. Refer to Ignition Coil REMOVAL / INSTALLATION .

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.

Scheme 22

The plugs may be cleaned using commercially available spark plug cleaning equipment. After cleaning, file center electrode flat with a small point file or jewelers file before adjusting gap.

Adjust spark plug gap with a gap gauging tool (1).

Special care should be taken when installing spark plugs into the cylinder head spark plug wells. Be sure the plugs do not drop into the plug wells as electrodes can be damaged.

Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap or a cracked porcelain insulator.

1. Start the spark plug into the cylinder head by hand to avoid cross threading.
2. Tighten spark plugs. Refer to «SPECIFICATIONS - TORQUE - IGNITION»(ref-247622-S29114618182007020100000) .
3. Before installing ignition coil(s), check condition of coil o-ring and replace as necessary. To aid in coil installation, apply silicone to coil o-ring.
4. Install ignition coil(s). Refer to Ignition Coil «REMOVAL»(ref-247622-S38629178342007020100000) / «INSTALLATION»(ref-247622-S30041121842007020100000) .

Special care should be taken when installing spark plugs into the cylinder head spark plug wells. Be sure the plugs do not drop into the plug wells as electrodes can be damaged.

Always tighten spark plugs to the specified torque. Over tightening can cause distortion resulting in a change in the spark plug gap or a cracked porcelain insulator.

1. Start the spark plug into the cylinder head by hand to avoid cross threading.
2. Tighten spark plugs. Refer to «SPECIFICATIONS - TORQUE - IGNITION»(ref-247622-S29114618182007020100000) .
3. Before installing ignition coil(s), check condition of coil O-ring and replace as necessary. To aid in coil installation, apply silicone to coil o-ring.
4. Install ignition coil(s). Refer to Ignition Coil «REMOVAL»(ref-247622-S38629178342007020100000) / «INSTALLATION»(ref-247622-S30041121842007020100000) .

Scheme 23

The ignition switch (5) is located on the steering column (4). It is used as the main on/off switching device for most electrical components. The mechanical key cylinder is used to engage/disengage the electrical ignition switch.