Part 2 of 2

ELECTRONIC ENTRY MODULE
The Viper Coupe and Roadster utilize an Electronic Entry Module (EEM). The module is located on the left side of the transmission tunnel, above the knee bolster. It is secured with a rubber strap. It contains a 32-way and two 6-way connectors. There is a green six way connector and a black six way connector. The module is connected to the CCD bus and transmits the "OK to run" message to the PCM when the theft alarm function is not tripped. It also receives the vehicle speed message from the bus and through a hardwired backup circuit.

The Coupe and Roadster will use electric door latches to accomplish opening and closing of the vehicle doors and electronics to accomplish the lock function that was typically performed with linkage inside the door. The system utilizes electric latches inside the door and micro switches both inside and outside the vehicle. These switches are inputs to the EEM and if the conditions are correct, the EEM will unlatch the doors. The lock function is simply the ignoring of the switch inputs that would normally cause the EEM to open the doors. There is no mechanical lock inside the door. This results in fewer moving parts and problems associated with packaging the linkage mechanisms.

The Electronic Entry Module provides remote keyless entry functions as well as vehicle theft alarm functions, electric locking/unlocking and the opening or power unlatching of the doors. The Coupe and Roadster will power unlatch the doors based only on inputs from the switches on the inside or the outside of the vehicle. The unlock button on the fob will not power unlatch the door. It also allows for the rolling lock feature, the only difference from other rolling lock systems is that specific throttle angle is not required for the locks to actuate. It is strictly a speed based system.

The inside and outside door handles control micro switches that are the inputs to the EEM. Located with the inside door switches are the lock rocker switches with LED indicators. The LED lock indicator informs the driver and passenger of the lock status of the doors. If the light is on, the doors are unlocked. Once the vehicle is started and driven approximately 8 mph (± 1.3) the doors will automatically lock and the LED will be extinguished at this time. The rolling lock feature cannot be disabled. If there is no activity for approximately one minute (input to the EEM) and the key is in the "ON" or "OFF" position, the LED will be turned OFF to reduce battery draw.

The driver and passenger lock switches are wired in parallel and form one input to the EEM. When the EEM receives a lock input, both doors are locked. When an unlock signal is input to the EEM, both doors are unlocked. If the key is on, and an inside door handle input is seen and vehicle speed is below 5 mph, both doors will be unlocked (and the door's handle that was actuated will be power unlatched). The lock switches are a momentary contact rocker type switch and either switch will lock or unlock both doors. In case of an electrical failure that would render the EEM system inoperable, there is an emergency mechanical release for the door located in the "B" pillar area of the door. This can be accessed through the liftglass area from outside the vehicle.

Coupe Only
The only way to access the driver compartment of the vehicle once it is locked, (without setting off the alarm) is with the key fob. There is an exterior lock cylinder for the lift glass, that allows opening with the key. This cylinder is not equipped with a disarm function. If the liftglass is opened with the key when the alarm is armed, it will set off the alarm. There is a liftglass ajar switch that mounts on the left gas prop (on the coupe). When the liftglass is opened, the outer shell of the gas prop allows a micro switch to close and the liftglass ajar circuit is grounded. The EEM monitors this circuit and knows the glass is open. If the liftglass is broken, the prop will extend and trip the alarm. By utilizing a prop switch in this manner, the vehicle is protected against opening or breakage of the liftglass. The roadster trunk latch and key cylinder are not protected by the theft system. Opening of the trunk when the theft alarm is armed will not cause it to be tripped.

Coupe and Roadster
The key fobs are unique to Viper and utilize a rolling code system. The rolling code feature changes a portion of the key fob message each time it is used. The key fob message and the receiver message change together. Under certain conditions with a rolling code system, the receiver and transmitter can fall out of synchronization. By pressing the lock and unlock buttons together, and holding until the horn chirps, the system will resynchronize. The system will take 5-10 seconds to respond with a horn chirp and normal operation resumes. This is not the same as programming a key fob.

The system will accept up to four fob codes and the system can be programmed with either the DRB III or by connecting a programming wire to ground and placing the module in programming mode. If the system is set up for programming, all key fobs for this vehicle must be programmed at the same time. When the module is placed in the program mode, all previous information from the transmitters is erased and no information is written there until the system recognizes a valid key fob. Pressing both lock and unlock buttons on the key fob at the same time will cause the system to respond with a horn chirp after approximately ten seconds. Then any other transmitters may be programmed. There is a time out after 60 seconds of inactivity (no further transmitters recognized). If the system times out, it will have to be returned to the programming mode with the DRB III or by disconnecting and re-connecting the green programming wire located near the module connectors. The DRB "Theft Alarm Monitor Screen" contains information about how many fobs have been programmed and if a valid fob message has been received. The horn chirp feature can not be disabled.

The security portion of the module performs typical security functions. The system can be actively armed by pressing the lock button on the key fob. The system responds with a single horn chirp, if the message is from a valid (programmed) key fob. This information can also be accessed on the VTSS monitor screen with the DRB III. The system will passively arm if the ignition is turned off and the key is removed, the hood and lift glass (coupe) are closed, and while a door is open, the door lock button is pressed. The system will arm immediately upon door closure. There will be no horn chirp.

The security LED will then flash at a 10% duty cycle. The system can be disarmed with a programmed key fob or by inserting the ignition key in the disarm switch. This switch is located in the storage cubby box, when turning the key the system is disarmed. It can only be used to disarm the VTSS, not to arm the system. When the alarm is tripped, the park lamps will flash and the horn will sound, indicating that the vehicle has been tampered with. The alarm can be tripped by opening doors, hood, liftglass (coupe) or turning the ignition on. Once tripped, the alarm will sound for 2.5 minutes. The park and tail lamps will flash for approximately 18 minutes. The PCM will not allow the engine to start. If the EEM has been tripped and 18 minutes have passed, the horn will chirp 3 times upon unlocking with the key fob to alert the driver that a theft condition may have taken place. Normal disarming with the key fob will result in no horn chirps, but will flash the park and tail lamps.

Diagnostics
The EEM system is fully addressable with DRB III and it is the recommended method for diagnosis. The EEM system does not display any Diagnostic Trouble Codes. All of the input switches to the EEM can be read with DRB under the I/O screen. The doors can be unlatched with the DRB under actuator tests. If the inputs are OK and the outputs can be cycled with the DRB, the problem is usually the Electronic Entry Module.

VEHICLE COMMUNICATION
The Chrysler Collision Detection multiplex (CCD bus) consists of a twisted pair of wires. These wires run from one module to another. They receive and deliver coded information between the modules. The information is coded to identify the message as well as the importance of the message. When there are multiple messages trying to access the CCD bus at one time, the code determines the message that has higher priority, and is then allowed to access the bus first.

The two wires of the twisted pair that make up the CCD multiplex system are called "bus +" (bus plus) and "bus -" (bus minus) respectively. Each wire has a measurable voltage level of roughly 2.5 volts. In order to maintain the 2.5 volts on each line and provide a means of transportation for the coded messages, there is a "voltage divider network" located in the module that supplies bus bias or voltage. Along with the module that supplies bias, some modules provide termination. Bias is the voltage necessary to make the bus operational. Atleast one point of termination is necessary, some Systems use more than one. Some modules are capable of biasing and terminating the bus by themselves. Termination in the circuitry (a 120 ohm resistor placed across the bus) is required to complete the voltage divider network and also provides some electromagnetic protection for the bus. Without termination, voltage on the bus goes to approximately 5 volts on one wire and 0 volts on the other wire.

NOTE: Communication over the bus is essential to the proper operation of the vehicle's on-board diagnostic systems and the DRB. Problems with the operation of the bus or DRB must be corrected before proceeding with diagnostic testing.

Bus Failure Messages

Short to Battery - Either or both of the bus wires are shorted to the battery potential.

Short to 5 Volts - Either or both of the bus wires are shorted to a 5-volt potential.

Short to Ground - Either or both of the bus wires are shorted to the ground.

Bus (+) & Bus (-) Shorted Together - The two bus wires are shorted together.

No Termination - The bus system has lost connection with all of its terminators.

Bus Bias Level Too Low - Either or both of the bus wire potentials are significantly below their normal 2.5 volts.

Bus Bias Level Too High - Either or both of the bus wire potentials are significantly above their normal 2.5 volts.

No Bus Bias - The bus system has lost connection with all modules that provide bias.

Bus (+) Open - The bus (+) wire has lost connection with termination and/or bias.

Bus (-) Open - The bus (-) wire has lost connection with termination and/or bias.

Not Receiving Bus Messages Correctly - The DRB III cannot communicate over the bus and does not know why.

USING THE DRB III
Refer to the DRB user's guide for instruction and assistance with reading trouble codes, erasing trouble codes and other DRB functions. The Entry Module and Airbag Control Module all communicate with the DRB for ease of diagnosis.

DRB III ERROR MESSAGES AND BLANK SCREEN
Under normal operation, the DRB will display one of only two error messages:
- User-Requested WARM Boot or User-Requested COLD Boot
If the DRB should display any other error message, record the entire display and call the STAR Center for information and assistance. This is a sample of a typical error message display.

ver: 2.14
date: 26 Jul93
file: key_itf.cc
date: Jul 26 1993
line: 548
err: Ox1
User-Requested COLD Boot

Press MORE to switch between this display and the application screen. Press F4 when done noting information.

DRB III Does Not Power Up (Blank Screen)
If the LED's do not light or no sound is emitted at start up, check for loose cable connections or a bad cable. Check the vehicle battery voltage (data link connector cavity 16). A minimum of 11 volts is required to adequately power the DRB.

If all connections are proper between the DRB and the Vehicle or other devices, and the vehicle battery is fully charged, an inoperative DRB may be the result of faulty cable or vehicle wiring. Refer to Communication in Table of Contents.

DRBIII Scan Tool:

Display Is Not Visible
Low temperatures will affect the visibility of the display. Adjust the contrast to compensate for this condition,

SAFETY
TECHNICIAN SAFETY INFORMATION

WARNING: ENGINES PRODUCE CARBON MONOXIDE THAT IS ODORLESS, CAUSES SLOWER REACTION TIME, AND CAN LEAD TO SERIOUS INJURY. WHEN THE ENGINE IS OPERATING, KEEP SERVICE AREAS WELL VENTILATED OR ATTACH THE VEHICLE EXHAUST SYSTEM TO THE SHOP EXHAUST REMOVAL SYSTEM.

Set the parking brake and block the wheels before testing or repairing the vehicle. It is especially important to block the wheels on front wheel drive vehicles; the parking brake does not hold the drive wheels. When servicing a vehicle, always wear eye protection, and remove any metal jewelry such as watchbands or bracelets that might make an inadvertent electrical contact.

When diagnosing a body system problem, it is important to follow approved procedures where applicable. These procedures can be found in General Information (Specifications). Following these procedures is very important to the safety of individuals performing diagnostic tests.

VEHICLE PREPARATION FOR TESTING
Make sure the vehicle being tested has a fully charged battery. If it does not, false diagnostic codes or error messages may occur.

SERVICING SUB-ASSEMBLIES
Some components of the body system are intended to be serviced in assembly only. Attempting to remove or repair certain system sub-components may result in personal injury and/or improper system operation. Only those components with approved repair and installation procedures should be serviced.

DRB III SAFETY INFORMATION

WARNING: EXCEEDING THE LIMITS OF THE DRB MULTIMETER IS DANGEROUS. IT CAN EXPOSE YOU TO SERIOUS OR POSSIBLE FATAL INJURY. CAREFULLY READ AND UNDERSTAND THE CAUTIONS AND THE SPECIFICATION LIMITS.

- Follow the vehicle manufacturer's service specifications at all times.
- Do not use the DRB if it has been damaged.
- Do not use the test leads if the insulation is damaged or if metal is exposed.
- To avoid electrical shock, do not touch the test leads, tips, or other circuits being tested.
- Choose the proper range and function for the measurement. Do not try voltage or current measurements that may exceed the rated capacity.
- Do not exceed the limits shown in the table below:

FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0-1.12 megohms
Frequency Measured 0 - 10 kHz
Frequency Generated
Temperature -58 - 11000 °F
-50 - 6000 °C

*Ohms cannot be measured if voltage is present. Ohms can be measured only in a non-powered circuit.

- Voltage between any terminal and ground must not exceed 500 V DC or 500 V peak AC.
- The circuit being tested must be protected by a 10A fuse or circuit breaker.
- Use the low current shunt to measure circuits up to 10A. Use the high current clamp to measure circuits exceeding 10A.
- When testing for the presence of voltage or current, make sure the meter is functioning correctly. Take a reading of a known voltage or current before accepting a zero reading.
- when measuring current, connect the meter in series with the load.
- Disconnect the live test lead before disconnecting the common test lead.
- When using the meter function, keep the DRB away from spark plug or coil wires to avoid measuring error from outside interference.

VEHICLE DAMAGE WARNINGS
Before disconnecting any control module, make sure the ignition is "OFF". Failure to do so could damage the module. When testing voltage or continuity at any control module, use the terminal side (not the wire end) of the connector. Do not probe a wire through the insulation; this will damage it and eventually cause it to fail because of corrosion. Be careful when performing electrical tests so as to prevent accidental shorting of terminals. Such mistakes can damage fuses or components. Also, a second code could be set, making diagnosis of the original problem more difficult.

REQUIRED TOOLS AND EQUIPMENT
DRB III (Diagnostic Read-out Box)
Jumper wires
Ohmmeter
Voltmeter
8310 Airbag System Load Tool

GLOSSARY OF ACRONYMS
ACM airbag control module
AECM airbag electrical control module also called ACM
ASDM airbag system control module also called ACM
CCD Chrysler Collision Detection (vehicle communication bus)
DAB driver airbag
DLC data link connector
EEM electronic entry module
PAB passenger airbag
PCM powertrain control module
PDC power distribution center
SQUIB also called initiator (located in rear of airbag module)