Set Lamp; Diagnosis And Testing; Relays; Vehicle Theft Security System Or Vehicle Immobilizer System - Jeep 1997 Grand Cherokee Service Manual

ZG
DESCRIPTION AND OPERATION (Continued)

SET LAMP

The set lamp is a red light-emitting diode mounted
with the auto headlamp ambient light sensor on top
of the instrument panel near the driver side defroster
outlet. The set lamp receives fused battery feed at all
times and is grounded by the Body Control Module to
give a visible indication of the Vehicle Theft Security
System or vehicle immobilizer system status.
The set lamp cannot be repaired and, if damaged
or faulty, the set lamp/auto headlamp ambient light
sensor must be replaced as a unit.

DIAGNOSIS AND TESTING

VEHICLE THEFT SECURITY SYSTEM OR VEHICLE
IMMOBILIZER SYSTEM
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
The Vehicle Theft Security System (VTSS) or the
vehicle immobilizer system and the data bus network
should be diagnosed using the DRB scan tool and the
proper Body Diagnostic Procedures manual. The
DRB will provide confirmation that the bus is func-
tional, that the Body Control Module (BCM) is
receiving and sending the proper messages on the
bus, that the BCM is receiving the proper hard-wired
inputs and sending the proper hard-wired outputs,
and that the Powertrain Control Module is receiving
the bus messages from the BCM. Refer to the Vehicle
Theft Security System menu item on the DRB scan
tool for the procedures. Refer to 8W-39 - Vehicle
Theft Security System in Group 8W - Wiring Dia-
grams for complete circuit descriptions and diagrams.

RELAYS

The horn relay is located in the Power Distribution
Center (PDC) in the engine compartment. The auto
headlamp and park lamp relays are located in the
junction block in the passenger compartment. Each
of these relays can be tested as described in the fol-
lowing procedure, however the circuits they are used
in do vary. To test the relay circuits, refer to the cir-
cuit descriptions and diagrams in 8W-39 - Vehicle
Theft Security System in Group 8W - Wiring Dia-
grams.
GROUP 8M - PASSIVE
STEERING COLUMN,
VEHICLE THEFT/SECURITY SYSTEMS
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
Remove the relay from the PDC or junction block
as described in this group to perform the following
tests:
(1) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 2. If not OK, replace the faulty relay.
(2) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75
3. If not OK, replace the faulty relay.
(3) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
OR
30 and 87, and no continuity between terminals 87A
and 30. If OK, test the relay circuits. If not OK,
replace the faulty relay.

REMOVAL AND INSTALLATION

DOOR AJAR SWITCH

(1) Disconnect and isolate the battery negative
cable.
(2) Remove the screw that secures the door ajar
switch to the pillar at the rear of the door opening
(Fig. 1).
(3) Pull the switch from the mounting hole in the
door opening far enough to access the wire harness
connector.
(4) Unplug the wire harness connector from the
switch.
NUMBER TERMINAL LEGEND COMMON FEED IDENTIFICATION
COIL GROUND
COIL BATTERY
NORMALLY OPEN
NORMALLY CLOSED
TO GROUP 8M
STEERING COLUMN,
5 ohms. If OK, go to Step
Relay Terminals
8Q - 5
- PASSIVE
OR