RAM 1500 Van V8-5.2L CNG VIN T (1999)
Audible Warning Device Control Module: Description and Operation
CENTRAL TIMER MODULE
DESCRIPTION
A Central Timer Module (CTM) is used on this vehicle when it is equipped with the optional Vehicle Theft Security System (VTSS). In addition
to serving as the security system module, the CTM combines the functions of a chime/buzzer module, an intermittent wipe module, an illuminated
entry module, and a Remote Keyless Entry (RKE) module in a single unit.
The CTM is also able to control and integrate many of the additional electronic functions and features included on models with this option. The
CTM contains a central processing unit and interfaces with other modules in the vehicle on the Chrysler Collision Detection (CCD) data bus
network.
The CCD data bus network allows the sharing of sensor information. This helps to reduce wire harness complexity, reduce internal controller
hardware, and reduce component sensor current loads. At the same time, this system provides increased reliability, enhanced diagnostics, and
allows the addition of many new feature capabilities.
Intermittent wipe, wipe-after-wash, and speed sensitive intermittent wipe are some of the features that the CTM supports. The intermittent wipe
relay is one of the outputs that the CTM can control. The CTM is programmed to energize or de-energize the intermittent wipe relay in response to
certain inputs from the windshield wiper and washer switches and from the windshield wiper motor park switch.
For the speed sensitive intermittent wipe feature, the CTM also uses vehicle speed messages, which are received on the CCD data bus from the
Powertrain Control Module (PCM).
The CTM is mounted under the instrument panel, to the inboard side of the left center instrument panel support. For diagnosis of the CTM or the
CCD data bus, the use of a DRB scan tool and the proper Diagnostic Procedures are recommended. The CTM cannot be repaired and, if faulty or
damaged, it must be replaced.
The CTM controls features and functions of the power lock, illuminated entry, and Remote Keyless Entry (RKE) systems. The CTM receives hard
wired inputs from the power lock switches, CCD message inputs from the Powertrain Control Module (PCM) and Airbag Control Module (ACM),
and coded radio frequency inputs from the RKE transmitters. In response to those and many other inputs, the internal programming of the CTM
sends the proper outputs to control the power lock motors, the headlamp and horn relays, and the courtesy lamps.
The RKE receiver within the CTM has a memory function to retain the vehicle access codes of at least one, but no more than four RKE
transmitters. The receiver is designed to retain the transmitter codes in memory, even if the battery is disconnected.
Some of the features and functions of the power lock, illuminated entry and RKE systems made possible because of the communication of the
CTM on the CCD data bus network include:
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A door-lock inhibit feature which prevents the power lock system from being energized with a power door lock switch if the key is in the
ignition and/or the headlamps are on. However, the locks can still be operated manually, with a key, or energized with the RKE transmitter.
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A delay lock feature. With the delay lock feature, if a side or rear door is still open when a lock request is received by the CTM, the module
will automatically cycle all of the power lock motors to lock five seconds after the doors are closed.
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An enhanced accident response feature will unlock all doors, then prevent the power door lock system from locking the doors for a
predetermined time interval, after receiving a CCD message from the ACM indicating a frontal impact of the vehicle requiring airbag
deployment. This feature will also turn on the courtesy lamps ten seconds after receiving the ACM deployment message, if the CCD vehicle
speed message from the PCM indicates that the vehicle is not moving. Of course, these responses are dependent upon functional battery power
and wiring circuitry following the impact.
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Rolling door locks is a programmable feature of the power lock system. This feature will automatically lock all of the doors and the liftgate
after the vehicle reaches a speed of about 24 kilometers-per hour (15 miles-per-hour) or greater. This feature will also lock the doors if a door
is opened, then closed again, at any speed above 24 kilometers-per-hour (15 miles-per-hour).
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A programmable feature of the RKE system is the enabling or disabling of the horn chirp following activation of the RKE Lock function. This
feature can be enabled or disabled and, if enabled, the horn chirp duration (twenty or forty milliseconds) can be selected.
One of the features that the CTM supports and controls is the Vehicle Theft Security System (VTSS). In the VTSS, the CTM receives hard-wired
inputs from the door ajar, front door lock cylinder, and ignition switches. The programming in the CTM allows it to process the information from
these inputs and send control outputs to energize or de-energize the headlamp (or security) relay, horn relay, and the security lamp. The CTM also
sends CCD data bus messages to the Powertrain Control Module (PCM) to control the engine no-run feature of the VTSS.
The CTM also contains the receiver and control logic for the power lock and Remote Keyless Entry (RKE) systems, which are integrated into the
arming, disarming, and triggering functions of the VTSS.
