Discovery 2. Manual — part 253

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

SUNROOF

76-6-10 DESCRIPTION AND OPERATION

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

DESCRIPTION AND OPERATION 76-6-11

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

76-6-12 DESCRIPTION AND OPERATION

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