Discovery 2. Manual - part 672

 

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Discovery 2. Manual - part 672

 

 

SUNROOF

DESCRIPTION AND OPERATION

76-6-9

Rear sunroof rear switch

The rear sunroof rear switch is located in the roof console in front of the rear sunroof.  It controls the rear sunroof 
motor via the sunroof ECU.

The rear sunroof front switch supplies an earth signal through the rear sunroof isolation switch 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 rear 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 isolation switch closed, rear 
sunroof rear switch released

> 10,000

C0784-6

Ignition in position II, rear sunroof isolation switch closed, rear 
sunroof front switch open

< 0.5

C0785-9

Ignition in position II, rear sunroof isolation switch closed, rear 
sunroof front switch released

> 10,000

C0785-9

Ignition in position II, rear sunroof isolation switch closed, rear 
sunroof front switch closed

< 0.5

SUNROOF

76-6-10 DESCRIPTION AND OPERATION

Rear sunroof motor and microswitch

The rear sunroof motor and microswitch are located within the rear sunroof assembly.  The sunroof ECU controls the 
rear 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.

Operating Parameters (connector connected)

Connector/Pin 

No.

Condition

Voltage

Resistance, ohms

C0785-4

Ignition in position II, rear of rear sunroof switch pressed +voltage to C0785-

6

C0785-6

Ignition in position II, front of rear sunroof switch 
pressed

+voltage to C0785-

4

< 0.5

C0784-2

Ignition in position II, sunroof fully closed

+V Batt

C0784-2

Ignition in position II, sunroof not closed

> 10,0000

SUNROOF

DESCRIPTION AND OPERATION 76-6-11

Sunroof ECU

The sunroof ECU is located behind the head lining above the rear view mirror. Most functions of the sunroof ECU are 
covered under other components.

Sunroof ECU connector pin details - C0784

Sunroof ECU connector pin details - C0785

Pin No.

Description

Input/Output

1

Rear sunroof microswitch

Input

2

Front sunroof switch - open

Input

3

Not used

-

4

Sunroof microswitches - common

Input

5

Not used

-

6

Rear sunroof, rear switch - open

Input

7

Rear sunroof, front switch - open

Input

8

Front sunroof microswitch

Input

Pin No.

Description

Input/Output

1

Front sunroof motor forward

Output

2

ECU earth

Input

3

Battery power supply

Input

4

Rear sunroof motor backwards

Output

5

Front sunroof motor backwards

Output

6

Rear sunroof motor forwards

Output

7

Front sunroof switch - close

Input

8

Rear sunroof, front switch - close

Input

9

Rear sunroof, rear switch - close

Input

10

Sunroof enable

Input

SUNROOF

76-6-12 DESCRIPTION AND OPERATION

Operation

Ignition switched-off timeout 
There are three timeout modes for operating the sunroof assemblies after the ignition is switched off.  The BCU 
determines the vehicle's timeout mode.  The three modes are: 

l

When the ignition is switched off, no sunroof operation is permitted.

l

When the ignition is switched off, sunroof  remains functional for 45 seconds or until the driver door is opened.

l

When the ignition is switched off, sunroof  remains functional for 45 seconds or until any door is opened.

Sunroof open and close
Both sunroof assemblies operate in the same manner.  The front sunroof assembly has one switch while there are 
two switches to control rear sunroof assembly, a rear sunroof front switch and a rear sunroof rear switch.  

The sunroof ECU monitors the position of the sunroof microswitch to determine if the sunroof is to be tilted  or opened.

In order for the  sunroof to operate, either of the following conditions must exist:

l

Ignition switch in position II.

l

Ignition switched from on to off, doors closed (this may enable the system to operate for 45 seconds after the 
ignition is switched off, or until a door is opened).

When the sunroof is closed, pressing the rear of the sunroof switch causes the sunroof ECU to operate the sunroof 
motor and  open the sunroof.  When the sunroof opens, the sunroof microswitch opens.  The sunroof continues to 
open until the switch is released or the sunroof reaches the fully open position.

When the sunroof is open, pressing the front of  the sunroof switch causes the sunroof ECU to operate the sunroof 
motor and close the sunroof.  The sunroof ECU continues to operate the motor until the sunroof microswitch closes.  
This indicates to the sunroof ECU that the sunroof is fully closed.

Sunroof tilt 
Both sunroof assemblies operate in the same manner.  The front sunroof assembly has one switch while there are 
two switches to control rear sunroof assembly, a rear sunroof front switch and a rear sunroof rear switch.  

The sunroof ECU monitors the position of the sunroof microswitch to determine if the sunroof is to be tilted  or  opened.

In order for the sunroof to operate, either of the following conditions must exist.

l

Ignition in position II.

l

Ignition switched from on to off, doors closed (this may enable the system to operate for 45 seconds after the 
ignition is switched off, or until a door is opened).

When the sunroof is closed and the front of the sunroof switch is pressed, the sunroof ECU detects the combination 
of closed microswitch and front of sunroof switch being pressed and tilts the rear of the sunroof.  This causes the 
microswitch to open.  The sunroof continues to open until the switch is released or the sunroof reaches the fully open 
position.

When the sunroof is tilted  and the rear of the sunroof switch is pressed, the sunroof ECU detects the combination of 
open microswitch and rear of sunroof switch and closes the sunroof until the microswitch closes.  This indicates to the 
sunroof ECU that the sunroof is fully closed.

Rear sunroof isolation
The rear sunroof isolation switch prevents the rear sunroof rear switch from operating the rear sunroof.  This can be 
used to prevent small children sitting in the rear seat from playing with the rear sunroof.

Pressing the rear sunroof isolation switch opens the circuit between the rear sunroof rear switch and the sunroof ECU.  
The sunroof ECU ignores the rear sunroof switch until the rear sunroof isolation switch is pressed and the circuit 
closes.

 

 

 

 

 

 

 

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