DESCRIPTION
The 5-pin, 12-volt, Automatic Shutdown (ASD) relay is located in the Integrated Power Module (IPM). Refer to label on IPM cover for relay location.
The Camshaft Position Sensor (CMP) is bolted to the right-front side of the right cylinder head.
Scheme 1
The Camshaft Position Sensor (CMP) sensor (3) contains a hall effect device referred to as a sync signal generator. A rotating target wheel (tonewheel) 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 tonewheel. As the tonewheel 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 tonewheel 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 tonewheel 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 2
The CMP sensor 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 tonewheel. The tonewheel (4) is located at the front of the camshaft for the right cylinder head (2). As the tonewheel rotates, the notches (1) pass through the sync signal generator. The pattern of the notches (viewed counter-clockwise 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 3
The Camshaft Position Sensor (CMP) (3) is bolted to the front/top of the right cylinder head (1).
- Disconnect electrical connector at CMP sensor.
- Remove sensor mounting bolt (2).
- Carefully twist sensor from cylinder head.
- Check condition of sensor o-ring.
Scheme 4
The Camshaft Position Sensor (CMP) (2) is bolted to the front/top of the right cylinder head (1).
- Raise and support vehicle.
- Disconnect electrical connector (4) at CMP sensor.
- Remove sensor mounting bolt (3).
- Carefully twist sensor from cylinder head.
- Check condition of sensor o-ring.
OPERATION
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 crystal 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.
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 key-in ignition switch is integral to the ignition switch, which is mounted on the left side of the steering column.
The key-in ignition switch cannot be repaired and, if faulty or damaged, the entire ignition switch must be replaced.