Part 2 of 2

ELECTRO/MECHANICAL INSTRUMENT CLUSTER (EMIC)
For the domestic market there are 2 (two) Instrument Cluster types, Base and Premium. The Premium Instrument Cluster is equipped with a Tachometer and a Low Fuel indicator.

The Instrument Cluster Speedometer, Tachometer, and Engine Coolant Temperature gauges are positioned using PCI Bus messages received from the PCM. The Fuel gauge is a hard wired input from the Fuel Level Sensor in the Fuel Pump Module.

The Cluster also contains warning indicators that are illuminated by hard wired inputs or by messages received from other modules on the PCI Bus.

The Trip/Total Odometer is a Vacuum Fluorescent (VF) display that is controlled by PCI Bus messages received from the PCM. The VF display also displays the "Door", "Cruise", and "Trac" messages. If the Instrument Cluster experiences a loss of PCI Bus communication with other modules on the Bus, the Cluster will display "nobus" in the VF display.

The illumination lamps are hard wired in the Instrument Cluster. When the Park or Headlamps are turned ON, the Cluster receives a hard wire input from the Multi-Function Switch. The Cluster sends a Panel Lamps Dimmer Signal to ground through the Multi-Function Switch. The varying voltage drop is sensed by the Instrument Panel Drivers to create a corresponding amount of illumination dimming. This dimming level is then sent out from the Cluster to other components.

The Cluster will communicate with the DRB III to display PCI Engine Info, PCI Bus info, and certain inputs/outputs. The Cluster is also capable of performing a diagnostic Self-Test that is actuated by depressing and holding the Odometer trip reset stalk while cycling the ignition from the OFF to the ON position. The Cluster will position all of the gauges at specified calibration points and will illuminate all the PCI Bus controlled indicators. The Cluster will also illuminate each segment of the VF display.

If the Cluster does not detect voltage on the Courtesy Lamp circuit, the message "FUSE" will alternate with the odometer/trip odometer for 30 (thirty) seconds after the ignition is turned ON and for 15 (fifteen) seconds after the vehicle is first moved.

INTERIOR LIGHTING
The Courtesy Lamps are controlled by the instrument cluster. The instrument cluster is sometimes referred to as a "Smart Cluster Control Module". Some of the features that it controls are the courtesy lamps, chime, and all instrument illumination. It receives and sends messages to other modules via the PCI bus circuit. The front turn signals are wired through the cluster and then go to the front lamps. For vehicles equipped with Daytime Running Lamps, the DRL module is built into the cluster.

REMOTE KEYLESS ENTRY MODULE
The Remote Keyless Entry module controls the Power Door Locks and the Vehicle Theft Security System (VTSS). It also wakes up the Instrument Cluster to turn ON the illuminated entry when it senses a signal from the RKE transmitter. The module communicates with other modules via the PCI bus circuit.

The RKE module monitors the Airbag Control Module messages for the purpose of monitoring the deployment of the airbag. Upon receiving that message along with the verification that the ignition is ON and the vehicle speed is zero, it will provide the "enhanced accident response feature". This feature will cause the module to unlock all doors and the instrument cluster to turn the courtesy lamps ON.

The RKE module communicates with the Powertrain Control Module to receive vehicle speed information to activate the rolling door lock feature, receive the "okay to lock" message, to receive the vehicle information number and receive body style information. Two transmitters are supplied with the vehicle but a total of 4 can be programmed to the module. The horn chirp on vehicle lock command is customer programmable.

Vehicle Theft Security System
The VTSS monitors the vehicle doors, decklid, hood and the ignition for unauthorized operation. Additionally, the decklid key cylinder is monitored for tampering, such as attempts to punch out the key cylinder. The alarm activates by sounding the horn, flashing the headlamps, park lamps and the VTSS indicator in the instrument cluster. Locking the doors with the door lock switch (through following a normal exit sequence of opening the door, pressing the lock button, and closing the door), the door cylinder lock switches or the RKE transmitter arms the system. During the 16 second arming process the VTSS indicator will flash quickly and when the system is armed will slow down. THE SYSTEM WILL NOT ARM IF THE HOOD IS OPEN (switch is grounded), or the decklid security switch (knockout) is not grounded, the LED will stay ON steady during arming. The engine kill feature on domestic vehicles is accomplished via the Sentry Key Immobilizer Module (SKIM).

All of the sensors for the VTS system can be monitored using the DRB III. The DRB III is also useful to determine the cause of a customer complaint of the alarm going OFF with no apparent reason.

Power Door Locks
Central Locking
This feature allows the customer to lock/unlock all vehicle doors with the key from either front door cylinder lock switch. The customer can choose to program this feature to unlock all doors with one turn of the key or open the driver door only with the first turn of the key and open the other doors with the second turn. Altering the operation of the unlock function via the key cylinder switch from one turn to two turns will also alter the operation of the RKE transmitter from one press to two presses.

Rolling (Automatic) Door Locks
All vehicle doors are locked automatically once the vehicle reaches a speed of 15 mph and all doors are closed. This feature can be also be enabled! disabled by the customer.

Door Lock Inhibit
This feature disables the door lock command from the interior door lock switch whenever the driver door is open and the key is in the ignition. This prevents the driver from locking the keys in the ignition when using the power door locks. This feature is inoperable if the IOD fuse is not installed.

Power Decklid Release
Electrically releases the decklid upon two presses of the RKE transmitter decklid release button. This feature is disabled once the speed of the vehicle is greater than 5 mph. This feature may be altered with the DRB III to allow the decklid to be released with one press of the RKE transmitter decklid release button. The decklid can also be released from the switch in the glove box.

Panic Mode
Upon activation of the panic function, the headlamps and park lamps flash in an alternating manner, the horn pulses every second and the courtesy lamps are turned ON. The panic mode allow normal nighttime driving by allowing the headlamps and park lamps to be on steady when the headlamp switch is in the ON position. Panic mode is activated immediately by pressing the panic button once. It does not disarm the VTSS or unlock the doors. It is canceled by pressing the button a second time, reaching a vehicle speed greater than 15 mph or after 3 minutes has elapsed in panic mode. Once panic mode has been activated there is a 2-second delay before it will turn OFF. Once it is cancelled there is a 2-second delay before it can be reactivated. This is to avoid the problem of deactivating and immediate reactivating due to multiple button presses.




VEHICLE COMMUNICATION
The Programmable Communication Interface or PCI Bus is a single wire multiplexed network capable of supporting binary encoded messages shared between multiple modules. The PCI bus circuit is identified as D25 and is violet with a yellow tracer. The modules are wired in parallel. Connections are made in the harness using splices. The following modules are used on 2001 PL:
- Airbag Control Module
- Left Side Impact Airbag Control Module
- Right Side Impact Airbag Control Module
- Controller Antilock Brake
- Powertrain Control Module
- Radio
- CD Changer
- Remote Keyless Entry Module
- Sentry Key Immobilizer Module
- Transmission Control Module (If equipped)
- Mechanical Instrument Cluster

Each module provides its own bias and termination in order to transmit and receive messages. The bus voltage is at zero volts when no modules are transmitting and is pulled up to about seven and a half volts when modules are transmitting.




The bus messages are transmitted at a rate averaging 10800 bits per second. Since there is only voltage present when the modules transmit and the message length is only about 500 milliseconds, it is ineffective to try and measure the bus activity with a conventional voltmeter. The preferred method is to use the DRB III lab scope. The 12V square wave selection on the 20-volt scale provides a good view of the bus activity. Voltage on the bus should pulse between zero and about seven and a half volts. Refer to the figure for some typical displays.

The PCI Bus failure modes are broken down into two categories. Complete PCI Bus Communication Failure and individual module no response. Causes of a complete PCI Bus Communication Failure include a short to ground or battery on the PCI circuit. Individual module no response can be caused by an open circuit at the module, or an open battery or ground circuit to the affected module.

Symptoms of a complete PCI Bus Communication Failure would include but are not limited to:
- All gauges on the MIC stay at zero
- All telltales on MIC illuminate
- MIC backlighting at full intensity
- No response received from any module on the PCI bus (except PCM)
- No start (if equipped with Sentry Key Immobilizer)

Symptoms of Individual module failure could include any one or more of the above. The difference would be that at least one or more modules would respond to the DRB III.

Diagnosis starts with symptom identification. If a complete PCI Bus Communication Failure is suspected, begin by identifying which modules the vehicle is equipped with and then attempt to get a response from the modules with the DRB III. If any modules are responding, the failure is not related to the total bus, but can be caused by one or more modules PCI circuit or power supply and ground circuits. The DRB III may display "BUS +/- SIGNALS OPEN" OR "NO RESPONSE" to indicate a communication problem. These same messages will be displayed if the vehicle is not equipped with that particular module. The CCD error message is a default message used by the DRB III and in no way indicates whether or not the PCI bus is operational. The message is only an indication that a module is either not responding or the vehicle is not equipped.