Jeep 1997 Grand Cherokee Service Manual page 420

8E - 18 INSTRUMENT PANEL SYSTEMS
DIAGNOSIS AND TESTING (Continued)
(1) Unplug the coolant level sensor wire harness
connector on the coolant reserve bottle. Check for
continuity between the ground circuit cavity of the
wire harness connector and a good ground. There
should be continuity. If OK, go to Step 2. If not OK,
repair the open circuit as required.
(2) With the engine coolant at the proper level,
check the resistance between the two terminals of
the coolant level sensor. The resistance should be
3000 to 3500 ohms. If OK, go to Step 3. If not OK,
replace the faulty sensor.
(3) Disconnect and isolate the battery negative
cable. Remove the VIC module as described in this
group. Unplug the VIC module wire harness connec-
tor. Check for continuity between the engine coolant
level switch sense circuit cavity of the VIC wire har-
ness connector and a good ground. There should be
no continuity. If OK, go to Step 4. If not OK, repair
the short circuit as required.
(4) Check for continuity between the engine cool-
ant level switch sense circuit cavities of the VIC wire
harness connector and the engine coolant level sensor
wire harness connector. If OK, replace the faulty VIC
module. If not OK, repair the open circuit as
required.
FOUR-WHEEL DRIVE DISPLAY AND
INDICATORS/SERVICE 4WD SWITCH
If the problem being diagnosed is related to an
incorrect or no four-wheel drive display or indicator
functions, be certain to confirm that the problem is
with the VIC module and transfer case switch cir-
cuits, and not with a Powertrain Control Module
(PCM) with an incorrect Vehicle Identification Num-
ber (VIN). This condition can only occur if the origi-
nal PCM was replaced with a unit from another
vehicle. The VIC module uses the VIN message
received on the CCD data bus from the PCM to
determine if the vehicle is equipped with two-wheel
drive or four-wheel drive.
If a four-wheel drive vehicle has a two-wheel drive
VIN entered in the PCM, the VIC will ignore all
transfer case switch inputs. If a two-wheel drive
vehicle has a four-wheel drive VIN entered in the
PCM, the rear wheels in the VIC display will not
light. Use a DRB scan tool and the proper Power-
train Diagnostic Procedures manual to confirm the
VIN in the PCM.
In addition, it should be noted that a VIC "Service
4WD Switch" message on a two-wheel drive vehicle
can occur if a short circuit occurs in the transfer case
switch circuits from the VIC module, in combination
with a PCM having a four-wheel drive VIN. To locate
the short circuit, start at Step 3 of the following diag-
nostic procedure. Two-wheel drive models do have
the same VIC wire harness provisions as four-wheel
drive models.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT
SYSTEMS BEFORE ATTEMPTING STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL COM-
PONENT DIAGNOSIS OR SERVICE. FAILURE TO
TAKE THE PROPER PRECAUTIONS COULD RESULT
IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) Unplug the wire harness connector at the
transfer case switch. Check for continuity between
the ground circuit cavity of the transfer case switch
wire harness connector and a good ground. There
should be continuity. If OK, go to Step 2. If not OK,
repair the open circuit as required.
(2) Check the transfer case switch continuity while
shifting the transfer case shift lever to the proper
positions. The switch continuity should be as shown
in (Fig. 2). If OK, go to Step 3. If not OK, replace the
faulty switch.
(3) Disconnect and isolate the battery negative
cable. Remove the VIC module as described in this
group. Unplug the VIC module wire harness connec-
tor.
(4) Locate two pairs of wire harness connectors
located in the wire harness leading to the VIC mod-
ule. The wire harness connectors should be taped
back to the harness. One pair of connectors are black
with a single cavity. The other pair are red with two
cavities. If the vehicle has the Quadra-Trac 4WD
transfer case, only the red wire harness connectors
should be joined. If the vehicle has the Command-
Trac or Selec-Trac 4WD transfer case, only the black
wire harness connectors should be joined. In all
cases, only one pair of wire harness connectors
should be joined. If OK, go to Step 5. If not OK, cor-
rect the wire harness connections as required.
(5) Refer to the VIC 4WD Display Characteristics
chart (Fig. 3). Check the continuity of the circuit for
the indicator lamp or wheel lamp that is not func-
tioning between the VIC module wire harness con-
nector and the transfer case switch wire harness
connector. There should be continuity. If OK, replace
the faulty VIC module. If not OK, repair the open cir-
cuit as required.
REAR LAMP FAILURE
Refer to the diagnosis for the lamp outage module
in Group 8L - Lamps to diagnose this feature of the
VIC module. Refer to 8W-46 - Message Center in
Group 8W - Wiring Diagrams for complete circuit
descriptions and diagrams.
TURN SIGNAL ON
Refer to Group 8J - Turn Signal and Hazard Warn-
ing Systems for more information on this feature of
the VIC module. The VIC module uses its internal
ZG