Dakota Quad Cab 2WD V8-5.9L VIN Z LDC (2002)
Central Timer Module ( CTM ) High Option: Description and Operation
Functional Operation
Airbag System
AIRBAG SYSTEM
The airbag system is designed to provide increased driver and passenger protection if the vehicle is involved in a front end collision. The system is
most effective when used in conjunction with the seat belt system.
The Airbag Control Module (ACM) is an electronic module that monitors the airbag system for proper operation, stores Diagnostic Trouble Code
(DTCs), controls the airbag warning lamp and chime contains the sensor and actuator that is responsible for airbag deployment. There are no external
impact sensors. The ACM is mounted on a special bracket that is fastened to the floor of the truck at the bottom of the instrument panel. It is located
forward of the console. The ACM provides diagnostic information (DTCs) to the technician through the DRB III via the PCI bus. Some circuits are
tested continuously; others are checked only under certain circumstances. The warning lamp and chime are driven with messages relayed to the
Electro/ Mechanical Instrument Cluster (EMIC and CTM) from the ACM via the PCI bus.
The AIRBAG warning lamp and chime are the only point at which "symptoms" of a system malfunction can be observed by the customer. When- ever
the ignition key is turned to the "run" or "start" position, the airbag control module performs a lamp check by turning the AIRBAG warning lamp ON
for 6-8 seconds. If the lamp remains OFF, it means that the ACM has checked the system and found it to be free of discernible malfunctions. If the
lamp remains ON, there could be an active fault in the system or the circuit that operates the lamp may be shorted to ground. If the lamp comes ON
and stays ON for a period longer than 6-8 seconds, then goes OFF; there is usually an intermittent problem in the system.
WARNING: THE AIRBAG CONTROL MODULE CONTAINS THE IMPACT SENSOR, WHICH ENABLES THE SYSTEM TO
DEPLOY THE AIRBAG. BEFORE ATTEMPTING TO DIAGNOSE OR SERVICE ANY AIRBAG SYSTEM OR RELATED STEERING
WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENTS YOU MUST FIRST DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE. THEN WAIT TWO MINUTES FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE FURTHER SYSTEM SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO DO
THIS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY. NEVER STRIKE OR
KICK THE AIRBAG CONTROL MODULE, AS IT CAN DAMAGE THE IMPACT SENSOR OR AFFECT ITS CALIBRATION. IF AN
AIRBAG CONTROL MODULE IS ACCIDENTALLY DROPPED DURING SERVICE, THE MODULE MUST BE SCRAPPED AND
REPLACED WITH A NEW UNIT.
Passenger Side Airbag ON-OFF Switch
The Passenger Airbag ON-OFF Switch allows the customer to turn the passenger airbag function ON or OFF. The OFF indicator will be illuminated
whenever the switch is turned to the OFF position and for 2 seconds at ignition ON for an indicator bulb test. The switch assembly is mounted in the
center of instrument panel to make the OFF indicator visible to all front seat occupants.
WARNING: ALWAYS CHECK THE PASSENGER AIRBAG ON-OFF SWITCH POSITION BEFORE DRIVING THE VEHICLE. A
SWITCH IN THE WRONG POSITION INCREASES THE RISK OF SERIOUS INJURY OR DEATH IN A COLLISION.
To operate, insert the ignition key into the switch keyhole, push key in to release the internal plunger, and rotate to the desired switch position. The
spring-loaded locking plunger prevents the user from leaving the key in the switch. The key will be automatically ejected when force is not applied.
The ignition key is the only key or object that should ever be inserted into the switch.
NOTE: Do not turn the ON-OFF switch with the ignition on.
The ACM continuously monitors the resistance of the Passenger Airbag ON-OFF Switch circuits to identify the switch position and provide circuit
diagnostics. The ON-OFF switch ON position resistance is 175 to 190 ohms and the OFF position resistance is 820 to 870 ohms. If the ON-OFF
switch circuits are open, shorted to ground or battery the ACM will set active and stored DTC. Upon receiving a switch diagnostic trouble code the
airbag warning indicator, in the instrument cluster, will be turned ON by the ACM. Whenever the airbag warning indicator is illuminated, the ACM
should be the first module interrogated.
WARNING: IGNORING THE AIRBAG WARNING LIGHT IN YOUR INSTRUMENT PANEL COULD MEAN THE PASSENGER
AIRBAG ON-OFF SWITCH IS NOT FUNCTIONAL AND THE AIRBAG MAY DEPLOY IF AN IMPACT OCCURS. IF THE AIRBAG
WARNING LIGHT TURNS ON WHILE DRIVING, THE AIRBAG ON-OFF SWITCH SETTING WILL REMAIN FUNCTIONAL FOR
THAT KEY CYCLE. IF THE AIRBAG WARNING LIGHT COMES ON AGAIN AT THE NEXT KEY ON AND STAYS LIT FOR MORE
THAN 6-8 SECONDS, THE ACM WILL DEFAULT TO PASSENGER AIRBAG ON.
SPECIAL TOOLS
Some airbag diagnostic test use special tools, 8310 and 8443 airbag load tool, for testing squib circuits. The load tools contain fixed resistive loads,
jumpers and adapters. The fixed loads are connected to cables and mounted in a storage case. The cables can be directly connected to some airbag
system connectors. Jumpers are used to convert the load tool cable connectors to the other airbag system connectors. The adapters are connected to the
module harness connector to open shorting clips and protect the connector terminal during testing. When using the load tool follow all of the safety
procedures in the service information for disconnecting airbag system components. Inspect the wiring, connector and terminals for damage or
misalignment. Substitute the airbag load tool in place of a Driver and Passenger Airbag, clockspring, or seat belt tensioner (use a jumper if needed).
