LAND ROVER DISCOVERY 1999 Workshop Manual

SUNROOF
DESCRIPTION AND OPERATION 76-6-1
SUNROOF DESCRIPTION AND OPERAT ION
Electric sunroof component location
RHD shown, LHD similar
1Sunroof front switches
2Front sunroof motor and microswitch
3Rear sunroof - rear switch4Sunroof ECU
5BCU

SUNROOF
76-6-2 DESCRIPTION AND OPERATION
Sunroof components

SUNROOF
DESCRIPTION AND OPERATION 76-6-3
1Glass panel
2Nut - glass panel
3Frame - glass panel
4Bolt - glass panel
5Drive cables and lifting assembly
6Screw - glass panel frame
7Sunroof frame
8Sunroof blind
9Screw - sunroof frame10Drain tubes
11Screw - motor
12Motor and gearbox
13Spacer - manual sunroof regulator
14Regulator - manual sunroof
15Handle - manual sunroof
16Screw - manual sunroof regulator
17Screw - manual sunroof handle

SUNROOF
76-6-4 DESCRIPTION AND OPERATION
System block diagram
1Passenger compartment fuse box
2BCU
3Sunroof ECU
4Front sunroof switch
5Front sunroof motor and microswitch6Rear sunroof - front switch
7Rear sunroof isolation switch
8Rear sunroof - rear switch
9Rear sunroof motor and microswitch

SUNROOF
DESCRIPTION AND OPERATION 76-6-5
Description
General
The sunroof system consists of a front and a rear sunroof assembly. Both sunroof assemblies slide and tilt to open.
The sunroof system consists of the following components:
lSunroof ECU.
lBCU.
lFront sunroof switch.
lFront sunroof motor and microswitch.
lRear sunroof - front switch.
lRear sunroof - rear switch.
lRear sunroof isolation switch.
lRear sunroof motor and microswitch.
The BCU enables operation of the sunroof ECU. If the sunroof ECU does not receive an enable signal from the BCU,
neither sunroof assembly operates. The BCU is located behind the glovebox. The sunroof ECU is located above the
headlining next to the front sunroof assembly.
TestBook diagnoses the sunroof ECU.

SUNROOF
76-6-6 DESCRIPTION AND OPERATION
Front sunroof switch
The front sunroof switch is located in the roof console above the windscreen in front of the front sunroof. It controls
the front sunroof motor via the sunroof ECU.
The front sunroof switch supplies an earth signal to the sunroof ECU. The pin at the ECU that receives the earth
signal determines whether ECU causes the sunroof to open or close.
TestBook cannot monitor the state of the front sunroof switch.
The following table lists the values which can be measured at the listed ECU pins when the conditions outlined are
met:
Signal values (connector connected)
Connector/Pin
No.Condition Resistance, ohms
C0784-2 Ignition in position II, front sunroof switch released > 10,000
C0784-2 Ignition in position II, front sunroof switch open < 0.5
C0785-7 Ignition in position II, front sunroof switch released > 10,000
C0785-7 Ignition in position II, front sunroof switch closed < 0.5

SUNROOF
DESCRIPTION AND OPERATION 76-6-7
Front sunroof motor and microswitch
The front sunroof motor is located within the front sunroof assembly. The sunroof ECU controls the front sunroof
motor.
The sunroof ECU determines the direction the sunroof motor runs. A battery signal to one side of the motor and an
earth to the other side of the motor causes the motor to turn in one direction, reversing the polarity through the same
pins causes the motor to turn in the opposite direction.
The following table lists the values which can be measured at the listed ECU pins when the conditions outlined are
met:
Signal values (connector connected)
Connector/Pin
No.Condition Voltage Resistance, ohms
C0785-5 Ignition in position II, rear of front sunroof switch
pressed+voltage to C0785-
5
C0785-1 Ignition in position II, front of front sunroof switch
pressed+voltage to C0785-
1< 0.5
C0784-8 Ignition in position II, sunroof fully closed +V Batt
C0784-8 Ignition in position II, sunroof not closed > 10,0000

SUNROOF
76-6-8 DESCRIPTION AND OPERATION
Rear sunroof - front switch
The rear sunroof front switch is located in the roof console above the windscreen in front of the front sunroof. It
controls the rear sunroof motor via the sunroof ECU.
The rear sunroof front switch supplies an earth signal to the sunroof ECU. The pin at the ECU that receives the earth
signal determines whether ECU causes the sunroof to open or close.
TestBook cannot monitor the state of the rear sunroof front switch.
The following table lists the values which can be measured at the listed ECU pins when the conditions outlined are
met:
Signal values (connector connected)
Connector/Pin
No.Condition Ohms
C0784-7 Ignition in position II, rear sunroof front switch released > 10,000
C0784-7 Ignition in position II, rear sunroof front switch open < 0.5
C0785-8 Ignition in position II, rear sunroof front switch released > 10,000
C0785-8 Ignition in position II, rear sunroof front switch closed < 0.5

SUNROOF
DESCRIPTION AND OPERATION 76-6-9
Rear sunroof isolation switch
The rear sunroof isolation switch is located in the roof console above the windscreen in front of the front sunroof. It
prevents the rear sunroof rear switch from operating the rear sunroof.
The rear sunroof isolation switch is in the earth path between the rear sunroof rear switch and the sunroof ECU.
Operating the rear sunroof isolation switch opens the circuit and prevents the rear sunroof rear switch from operating
the rear sunroof.
TestBook cannot monitor the state of the rear sunroof isolation switch.
The following table lists the values which can be measured at the listed ECU pins when the conditions outlined are
met:
Signal values (connector connected)
Connector/Pin
No.Condition Resistance, ohms
C0784-6 Ignition in position II, rear sunroof rear switch open, rear
sunroof isolation switch pressed> 10,000
C0784-6 Ignition in position II, rear sunroof rear switch open, rear
sunroof isolation switch released< 0.5
C0785-9 Ignition in position II, rear sunroof rear switch closed, rear
sunroof isolation switch pressed> 10,000
C0785-9 Ignition in position II, rear sunroof rear switch closed, rear
sunroof isolation switch released< 0.5