The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. This system includes seat belt switch inputs and dual stage front air bag modules. The SRS
system uses the seat belt switches to determine the front air bag deployment, and may only deploy one front
air bag, depending on the severity of a collision and whether the front occupants are belted or unbelted.
Information necessary to service the system safely is included in the SRS and SB section of this Service Man-
ual.

WARNING:

●

To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be per-
formed by an authorized NISSAN/INFINITI dealer.

●

Improper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and Air
Bag Module, see the SRS section.

●

Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses can be identified by yellow and/or orange harnesses or
harness connectors.

BCM (BODY CONTROL MODULE)

BCS-3

BCS

BCM (BODY CONTROL MODULE)

PFP:284B2

System Description

NKS003XH

BCM (Body Control Module) controls the operation of various electrical units installed on the vehicle.

BCM FUNCTION

BCM has combination switch reading function for reading the operation of combination switches (light, wiper,
washer, turn signal) in addition to a function for controlling the operation of various electrical components. Also
it has an interface function allowing it to receive signals from the combination meter, and send signals to ECM
using CAN communication.

COMBINATION SWITCH READING FUNCTION
Description

●

BCM reads combination switch (lighting switch, wiper switch) status, and controls various electrical com-
ponent according to the result.

●

BCM reads information of a maximum of 20 switches by combining five output terminals (OUTPUT 1-5)
and five input terminals (INPUT 1-5).

Operation Description

●

BCM activates transistors of output terminals (OUTPUT 1-5) periodically, and allows current to flow in
turn.

●

If any (1 or more) switches are turned ON, circuit of output terminals (OUTPUT 1-5) and input terminals
(INPUT 1-5) becomes active.

●

At this time, transistors of output terminals (OUTPUT 1-5) are activated to allow current to flow. When volt-
age of input terminals (INPUT 1-5) corresponding to that switch changes, interface in BCM detects volt-
age change, and BCM determines that switch is ON.

PKID0470E

BCS-4

BCM (BODY CONTROL MODULE)

Operation Table of BCM and Combination Switches

BCM reads operation status of combination switch using combinations shown in table below.

NOTE:
Headlamp system has a dual switch.

Sample Operation:

●

When lighting switch 1ST position is turned ON, contact in combination switch turns ON. At this time if
OUTPUT 4 transistor is activated, BCM detects that voltage changes in INPUT 5.

●

When OUTPUT 4 transistor is ON, BCM detects that voltage changes in INPUT 5, and judges that lighting
switch 1ST position is ON. Then BCM sends tail lamp and clearance lamp request signal to IPDM E/R
using CAN communication.

●

When OUTPUT 4 transistor is activated again, BCM detects that voltage changes in INPUT 5, and recog-
nizes that lighting switch 1ST position is continuously ON.

NOTE:
Each OUTPUT terminal transistor is activated at 10 ms intervals. Therefore after switch is turned ON, electri-
cal loads are activated with time delay. But this time delay is so short that it cannot be detected by human
senses.

PKIC0276E

PKID0471E

Content .. 227 228 229 230 ..