Jeep 1997 Grand Cherokee Service Manual page 938

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DESCRIPTION AND OPERATION
INTRODUCTION
The Drivers Door Module (DDM) controls both
power mirrors. The DDM adjusts the left mirror and
signals the Passenger Door Module (PDM) over the
CCD bus to adjust the right mirror. A push button
switch on the outside of the DDM controls the hori-
zontal and vertical position of both mirrors. The
DDM also has a selector switch with right, left and
center (off) positions for mirror selection.
Some models with Remote Keyless Entry (RKE)
have a memory feature that allows the RKE trans-
mitter to move the drivers seat and outside mirrors
to a saved positions. The memory feature also can set
the radio push buttons to preset stations.
POWER MIRROR
The circuits from the left outside mirror to the
Driver Door Module (DDM) and right mirror to Pas-
senger Door Module have identical circuit numbers.
Each mirror has two motors; an UP/DOWN motor
and a LEFT/RIGHT motor. The motors switch polar-
ity to allow mirror adjustment. The DDM and PDM
adjust mirror position by supplying power or ground
to the mirror motors.
Each mirror has a vertical position sensor and a
horizontal position sensor. The sensors in the left
mirror connect to the DDM. Sensors in the right mir-
ror connect to the PDM. The DDM and PDM deter-
mine horizontal position on circuit F85 and vertical
position on circuit F84. Circuit F86 provides ground
for each sensor.
If the vehicle is equipped with an automatic day/
night rear view mirror, the left power mirror also
automatically adjusts to varying ambient light inten-
sity. Circuits P114 and P112 connect the left power
mirror to the automatic day/night rear view mirror.
LEFT MIRROR ADJUSTMENT
The DDM adjusts the position of the left mirror.
When an UP adjustment is made, the DDM supplies
8W - 62 POWER MIRRORS
8W-62 POWER MIRRORS
power to the left mirror UP/DOWN motor on circuit
F71 and grounds circuit F73.
reveres. The DDM supplies power to circuit F73 and
grounds circuit F71.
power to the LEFT/RIGHT motor on circuit F75 and
grounds circuit F73.
DDM supplies power to circuit F73 and grounds cir-
cuit F75.
RIGHT MIRROR ADJUSTMENT
signals it receives over the CCD bus from the DDM.
When an UP adjustment is made, the PDM supplies
power to the right mirror UP/DOWN motor on circuit
F71 and grounds circuit F73.
reveres. The PDM supplies power to circuit F73 and
grounds circuit F71.
power to the LEFT/RIGHT motor on circuit F75 and
grounds circuit F73.
PDM supplies power to circuit F73 and grounds cir-
cuit F75.
HEATER ELEMENTS
circuit in the left power mirror. The Passenger Door
Module powers the heater element in the right mir-
ror. When the Body Control Module (BCM) detects
the operator pressed the rear window defogger
switch, it broadcasts the appropriate message to the
DDM and PDM over the CCD bus. The DDM and
PDM activate the heater elements in the mirrors
until the BCM no longer broadcasts the message on
the CCD bus.
circuit C16. On circuit Z1, the DDM and PDM pro-
vide ground for the heater elements.
When a DOWN adjustment is made, the polarity
During LEFT adjustments, the DDM supplies
For RIGHT adjustments, the polarity reverses. The
The PDM adjusts the right mirror in response to
When a DOWN adjustment is made, the polarity
During LEFT adjustments, the PDM supplies
For RIGHT adjustments, the polarity reverses. The
The Driver Door Module (DDM) powers the heater
The DDM and PDM power the heater element on
ZG