Ignition Control - Service Information

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:

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

0.6 - 0.9 Ohms 6,000 - 9,000 Ohms

Ignition timing is not adjustable on any engine.

3.7L V6 ZFR6F - 11G (NGK) 1.1 mm (0.043 in.)

SPECIFICATIONS - ENGINE FIRING ORDER - 3.7L 1-6-5-4-3-2

- 3.7L Crankshaft Position 28 21 205 Sensor - 3.7L Ignition Coil Mounting - 8 - 70 3.7L

Ignition switch mounting 3 - 26 screws * Do not apply any - - sealant, thread-locker or adhesive to bolts. Poor sensor performance may result. ** Torque critical tapered - - design. Do not exceed 15 ft. lbs. (20 N.m).

RELAY-AUTO SHUT DOWN

The ASD relay is located in the Totally Integrated Power Module (TIPM) (1). The TIPM is located in the engine compartment near the left inner fender (2). Refer to label on TIPM cover for relay location.

1. Remove TIPM cover. 2. Remove relay from TIPM. 3. Check condition of relay terminals and TIPM connector terminals for damage or corrosion. Repair if necessary before installing relay. 4. Check for pin height (pin height should be the same for all terminals within the TIPM connector). Repair if necessary before installing relay.

1. Refer to TIPM cover for ASD relay location. 2. Install relay to TIPM (1). 3. Install cover to TIPM.

SENSOR-CAMSHAFT POSITION

The Camshaft Position Sensor (CMP) (3) is bolted to the front/top of the right cylinder head (1).

  1.   Raise and support vehicle.
  2.   Disconnect electrical connector at CMP sensor.
  3.   Remove sensor mounting bolt (2).
  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 to 12 N.m (106 in. lbs). 5. Connect electrical connector to sensor.

COIL-IGNITION

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 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 (2) 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.

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). 5. Connect electrical connector to coil by snapping into position. 6. If necessary, install throttle body air tube.

SENSOR-KNOCK

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.

The two knock sensors (1) are bolted into the cylinder block under the intake manifold. The two sensors share a common wiring harness using one electrical connector (3). Because of this, they must be replaced as a pair.

NOTE: The left sensor is identified by an identification tag (LEFT) (2). 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. Remove intake manifold. Refer to INSTALLATION . 2. Disconnect knock sensor dual pigtail harness from engine wiring harness. This connection is made near rear of engine. 3. Remove both sensor mounting bolts. 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.

NOTE: The left sensor is identified by an identification tag (LEFT) (2). 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 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 sensor 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. Tighten to 15 +/- 2 ft. lbs. (20 N.m) (176 in. lbs). 4. Connect knock sensor wiring harness to engine harness at rear of intake manifold. 5. Install intake manifold. Refer to INSTALLATION .

SPARK PLUG

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.

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.

Spark plugs cables are not used with either the 3.7L or 4.0L V6 engines.

SWITCH-IGNITION

If the key removal effort is excessive on a vehicle with an automatic transmission first adjust the shift linkage. Refer to ADJUSTMENTS .

If the ignition switch effort is excessive, remove the ignition key cylinder from the steering column. Check the turning effort of the key cylinder. If the ignition key cylinder effort is excessive, replace the key cylinder. Refer to REMOVAL .

1 - KEY CYLINDER 2 - GEAR SHIFT LEVER 3 - MOUNTING HOLES 4 - STEERING COLUMN 5 - IGNITION SWITCH

NOTE: The steering column on vehicles equipped with an automatic transmission is not equipped with an internal locking shaft with the ignition cylinder. Alternative methods of locking the steering wheel for service will have to be used.

The tilt and standard column (4) have been designed to be serviced as an assembly; without wiring, switches, shrouds, steering wheel, etc. Most steering column components can be serviced without removing the steering column from the vehicle. See Fig. 12.

Safety goggles should be worn at all times when working on steering columns.

To service the steering wheel, switches or airbag, refer to RESTRAINTS - SERVICE INFORMATION article and follow all WARNINGS and CAUTIONS.

WARNING: The airbag system is a sensitive, complex electro-mechanical unit. Before attempting to diagnose, remove or install the airbag system components you must first disconnect and isolate the battery negative (ground) cable. Then wait two minutes for the system capacitor to discharge. Failure to do so could result in accidental deployment of the air bag and possible personal injury. The fasteners, screws and bolts, originally used for the airbag components, have special coatings and are specifically designed for the airbag system. They must never be replaced with any substitutes. Anytime a new fastener is needed, replace with the correct fasteners provided in the service package or fasteners listed in the parts books.

CAUTION: Do not hammer on steering column shaft. This may cause damage to the shaft or bearing.

CAUTION: Do not attempt to remove the pivot bolts to disassemble the tilting mechanism.

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

  1.   Remove the negative (ground) cable from the battery.
  2.   Disable the airbag. Refer to REMOVAL .
  3.   Remove the lower and upper shrouds.
  4.   Remove key cylinder. Refer to REMOVAL .
  5.   Disconnect the lower clockspring connectors.

6. Remove the wire retainer from the tilt lever bracket.

1 - IGNITION SWITCH 2 - TILT LEVER MECHANISM

7. Remove the tilt lever mounting screws to gain access to the ignition switch (1) mounting screws. See Fig.

1 - Ignition Switch Mounting Screws 2 - Non-Tilt Mounting Bracket Screws

8. For columns without tilt remove the bracket (2) to gain access to the ignition switch mounting screws (1). See Fig. 14

1 - Ignition Switch 2 - Ignition Switch Mounting Screws

9. Disconnect the electrical connector at rear of ignition switch (1). See Fig. 15. 10. Remove ignition switch mounting screws (2). 11. Using a small screwdriver, push on locking tab and remove switch from steering column.

For ignition switch electrical schematics, refer to Ignition Switch in the SYSTEM WIRING DIAGRAMS article.

MECHANICAL DIAGNOSIS (KEY DIFFICULT TO ROTATE) Refer to DIAGNOSIS AND TESTING .

CYLINDER-KEY/LOCK

CAUTION: The glow plugs operate on a 4.4-volt system. The glow plugs DO NOT tolerate any over voltage. Full battery voltage will destroy the glow plug immediately. DO NOT test the glow plugs with a 12V source as damage will occur to the glow plug.

CAUTION: Never bend, bump or knock the fast metallic glow plugs. Fast metallic glow plugs must not be handled loose in a container. Store, handle, and transport them only in original boxes. If there is any doubt about the proper condition of a glow plug, do not reuse it. Do not clean the glow plugs with abrasive or aggressive media. Avoid dipping the glow plug into fluids. Read Diagnostic Trouble Codes (DTCs). If a glow plug problem is indicated, do not start the engine.

CAUTION: Disregarding these instructions may cause severe engine damage.

Glow plugs are used to help start a cold or cool engine. The glow plugs will heat up and glow to heat the combustion chamber of each cylinder. An individual glow plug is used for each cylinder.

CAUTION: The glow plugs operate on a 4.4-volt system. DO NOT test the glow plugs with a 12 V source as damage will occur to the glow plug(s).

The Engine Control Module (ECM) monitors various engine sensors. When the ignition key is turned to the ON position, the ECM sends a signal to the glow plug module (relay) to turn on, and cycle, the glow plugs for a pre- determined amount of time, plus illuminate the glow plug light in the instrument panel. Once activated, the element inside of the core of the glow plug begins to glow. Each glow plug draws approximately 8 amps, for a total system amperage of 32 amps at 22° C (72° F) ambient temperature. If there is a fault with the glow plug system, the ECM will store a fault code.

CAUTION: DO NOT attempt to start the engine until the glow plug system tests correctly.

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 diagnostic information, and follow the diagnostic test(s) related to the active or stored DTCs.

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

The glow plug relay (module) (1) is located in the engine compartment. It is attached to the ECM mounting bracket (2).

The glow plug relay (module) (1) is located in the engine compartment. It is attached to the ECM mounting bracket (2).