Discovery 2. Manual - part 252

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:

l

Sunroof ECU.

l

BCU.

l

Front sunroof switch.

l

Front sunroof motor and microswitch.

l

Rear sunroof - front switch.

l

Rear sunroof - rear switch.

l

Rear sunroof isolation switch.

l

Rear 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