Part 4 of 4
POWER DOOR LOCKSCentral Locking (W/VTSS only)
This feature allows the customer to lock/unlock all vehicle doors with the key from either front door or liftgate lock cylinder 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 (including liftgate) are locked automatically once the vehicle reaches a speed of 15 mph (24 kph) and all doors (excluding liftgate) are closed. This feature can 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.
SENTRY KEY IMMOBILIZER SYSTEM (SKIS)
The SKIS is an immobilizer system designed to prevent unauthorized vehicle operation. The system consists of a Sentry Key Immobilizer Module (SKIM) and ignition key(s) called Sentry Key(s) which are equipped with a transponder chip. The SKIM communicates over the Programmable Communication Interface multiplex system (PCI) bus network to the instrument cluster, Powertrain Control Module (PCM), and the DRB III scan tool.
The SKIM sends messages to the instrument cluster over the PCI bus to control the VTSS indicator lamp. The SKIM sends a message to the instrument cluster to turn the lamp ON for about three seconds when the ignition is turned to the Run/Start position as a bulb test. If the indicator lamp comes ON and stays ON after the bulb test, it indicates that the SKIM has detected a system malfunction and/or that the SKIS has become inoperative. If an invalid key is detected in the ignition key cylinder with the ignition switch in the Run/Start position the SKIM will flash the VTSS indicator lamp ON and OFF.
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 2002 PT/PG:
- Airbag Control Module
- Left SIACM
- Right SIACM
- Controller Antilock Brake
- Powertrain Control Module (Gas only)
- Engine Control Module (Diesel only)
- Remote Keyless Entry Module
- Sentry Key Immobilizer Module
- Radio
- Transmission Control Module
- 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 7-1/2 volts when modules are transmitting.
The bus messages are transmitted at a rate averaging 10,800 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 7-1/2 volts. Refer to the figure for some typical displays.
The PCI Bus failure modes are broken down into two categories. PCI Bus Communication Failure and individual module no response. Causes of a 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 PCI Bus Communication Failure would include but are not limited to:
- All gauges on the EMIC stay at zero
- All telltales on EMIC illuminate
- EMIC backlighting at full intensity
- No response received from any module on the PCI bus (except PCM/ECM)
- 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 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 (+/-) SIGNAL 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.
NOTE: Communication over the bus is essential to the proper operation of the vehicles on-board diagnostic systems and the DRB III. Problems with the operation of the bus or DRB III must be corrected before proceeding with diagnostic testing. If there is a problem, refer to the Communications category of this manual.