Rear window defogger on Nissan ExSaloon N16

System Description NEEL0216 MODELS WITHOUT POWER DOOR LOCKS NEEL0216S01 The rear window defogger system is controlled by the rear window defogger timer. The rear window defogger operates only for approximately 15 minutes. The rear window defogger switch is integral to the air control. Power is supplied at all times
to rear window defogger relay terminal 5
through 20A fuse [No. 25, located in the fuse block (J/B)]. With the ignition switch in the ON or START position, power is supplied
through 10A fuse [No. 5, located in the fuse block (J/B)]
to rear window defogger relay terminal 1, and
to rear window defogger timer terminal 1. Ground is supplied to air control (rear window defogger switch) terminal 8 and rear window defogger timer terminal 4 through body grounds M14 and M68. With the rear window defogger switch (located in air control) ON, ground is supplied
to rear window defogger timer terminal 3
through air control (rear window defogger switch) terminal 8. Rear window defogger timer terminal 2 then supplies ground to the rear window defogger relay terminal 2. With power and ground supplied, the rear window defogger relay is energized. Power is supplied
through terminal 3 of the rear window defogger relay
to rear window defogger terminal +. Rear window defogger terminal - is grounded through body ground R102. With power and ground supplied, the rear window defogger filaments heat and defog the rear window. When the system is activated, the rear window defogger indicator illuminates in the air control. Power is supplied
from rear window defogger relay terminal 3
to air control (rear window defogger switch) terminal 4. Air control terminal 8 is grounded through body grounds M14 and M68. MODELS WITH POWER DOOR LOCKS NEEL0216S02 The rear window defogger system is controlled by the smart entrance control unit. The rear window defogger operates only for approximately 15 minutes. The rear window defogger switch is integral to the air control. Power is supplied at all times
to rear window defogger relay terminal 5
through 20A fuse [No. 25, located in the fuse block (J/B)] and
to smart entrance control unit terminal 49
through 7.5A fuse [No. 28, located in the fuse block (J/B)]. With the ignition switch in the ON or START position, power is supplied
through 10A fuse [No. 5, located in the fuse block (J/B)]
to rear window defogger relay terminal 1 and
to smart entrance control unit terminal 27. Ground is supplied to air control (rear window defogger switch) terminal 8 and smart entrance control unit terminals 43 and 64 through body grounds M14 and M68. With the rear window defogger switch (located in air control) ON, ground is supplied
to smart entrance control unit terminal 14
through air control (rear window defogger switch) terminal 1. Smart entrance control unit terminal 37 then supplies ground to the rear window defogger relay terminal 2. With power and ground supplied, the rear window defogger relay is energized. Power is supplied
through terminal 3 of the rear window defogger relay
to rear window defogger terminal +.
Rear window defogger terminal - is grounded through body ground R102. With power and ground supplied, the rear window defogger filaments heat and defog the rear window. When the system is activated, the rear window defogger indicator illuminates in the air control. Power is supplied
from rear window defogger relay terminal 3
to air control (rear window defogger switch) terminal 4. Air control (rear window defogger switch) terminal 8 is grounded through body grounds M14 and M68

Doesn't use a relay , controlled by lift gate control module . Your best bet , take it to a qualified repair shop .
Rear Window Defogger System Components
The rear window defogger system consist of the following components:
?€¢
HVAC control module

?€¢
Liftgate module (LGM)/endgate module (EGM)

?€¢
Rear window defogger grid

Rear Window Defogger Operation (With LGM)
Battery positive voltage is supplied through the LGM 2 fuse to the LGM for the rear window defogger system. When the rear window defogger switch is depressed, the HVAC control module illuminates the rear window defogger indicator, and sends a class 2 message to the LGM to enable the rear window defogger. The LGM enables the rear window defogger by allowing battery positive voltage to the rear window defogger.
When the rear window defogger switch is pressed for the first time, the defogger cycle lasts 10 minutes. Further operation results in 10 minute defogger cycles.
DTC B0283 Electric Rear Defrost Circuit - do you know what DTC'S - diagnostic trouble code's are ?
Circuit Description
The liftgate module (LGM)/endgate module (EGM) monitors the voltage level on the supply voltage circuit of the rear window defogger. The LGM/EGM test the supply voltage circuit of the rear window defogger every 160 milliseconds. With the rear window defogger inactive, the supply voltage circuit of the rear window defogger will have no voltage present. With the rear window defogger active, the supply voltage circuit of the rear window defogger will be near system voltage.

Your best bet , take it to a qualified repair shop .
SMART ENTRANCE CONTROL UNIT PFP:28596 Description EKS003A2 OUTLINE The smart entrance control unit totally controls the following body electrical system operations. ? Warning chime ? Rear window defogger and door mirror defogger ? Power door locks ? Remote keyless entry system ? Vehicle security system ? Interior lamp ? Battery saver control BATTERY SAVER CONTROL Interior Lamp/Map Lamp/Vanity Lamps The lamps turn off automatically when the interior lamp, map lamp or/and vanity lamps are illuminated with the ignition key in the OFF position, if the lamp remains lit by the door switch open signal or if the lamp switch is in the ON position for approximately 10 minutes. After lamps are turned off by the battery saver system, the lamps illuminate again when: ? Driver's door is locked or unlocked, ? Door is opened or closed, ? Key is inserted into or removed from the ignition key cylinder. Rear Window Defogger/Door Mirror Defogger Rear window defogger and door mirror defogger are turned off approximately 15 minutes after the rear window defogger switch is turned on. INPUT/OUTPUT

Warning chime Key switch (Insert) Ignition switch (ON) Lighting switch (1st or 2nd) Seat belt buckle switch LH Front door switch LH Warning chime (located in smart entrance control unit)

Nothing for you to remove ! Without a factory scan tool U can do nothing .
TIME CONTROL UNIT PFP:28491 Description (Without Power Door Locks) EKS003A6 OUTLINE The time control unit totally controls the following body electrical system operations. ? Warning chime ? Rear window defogger INPUT/OUTPUT System Input Output Warning chime Key switch (Insert) Ignition switch (ON) Lighting switch (1st or 2nd) Seat belt buckle switch LH Front door switch LH Warning chime (located in time control unit) Rear window defogger Ignition switch (ON) Rear window defogger switch Rear window defogger relay

SMART ENTRANCE CONTROL UNIT PFP:28596 Description EKS003A2 OUTLINE The smart entrance control unit totally controls the following body electrical system operations. ? Warning chime ? Rear window defogger and door mirror defogger ? Power door locks ? Remote keyless entry system ? Vehicle security system ? Interior lamp ? Battery saver control BATTERY SAVER CONTROL Interior Lamp/Map Lamp/Vanity Lamps The lamps turn off automatically when the interior lamp, map lamp or/and vanity lamps are illuminated with the ignition key in the OFF position, if the lamp remains lit by the door switch open signal or if the lamp switch is in the ON position for approximately 10 minutes. After lamps are turned off by the battery saver system, the lamps illuminate again when: ? Driver's door is locked or unlocked, ? Door is opened or closed, ? Key is inserted into or removed from the ignition key cylinder. Rear Window Defogger/Door Mirror Defogger Rear window defogger and door mirror defogger are turned off approximately 15 minutes after the rear window defogger switch is turned on.

Warning chime Key switch (Insert) Ignition switch (ON) Lighting switch (1st or 2nd) Seat belt buckle switch LH Front door switch LH Warning chime (located in smart entrance control unit)

Does it have power locks ?

TIME CONTROL UNIT PFP:28491 Description (Without Power Door Locks) EKS003A6 OUTLINE The time control unit totally controls the following body electrical system operations. ? Warning chime ? Rear window defogger INPUT/OUTPUT System Input Output Warning chime Key switch (Insert) Ignition switch (ON) Lighting switch (1st or 2nd) Seat belt buckle switch LH Front door switch LH Warning chime (located in time control unit) Rear window defogger Ignition switch (ON) Rear window defogger switch Rear window defogger relay

Fuse box rear , fuse #23 30 amp ! Do you know where this is located ? There is also a relay for the Rear window defogger , located in the same rear fuse box .
Fuse Block - Rear
Left side of the luggage compartment, behind the left rear wheel well . But you really need to know how it works , you can check fuse an relay .
Rear Window Defogger Operation
Battery positive voltage is supplied through the BATT 1 fuse in the underhood fuse block to the rear defog relay switched input. When the rear defog switch button is pressed, the body control module (BCM) energizes the rear defog relay by providing a B+ to the control circuit of the rear defog relay. This allows battery positive voltage from the relay switched input through the switch contacts and out the relay switched output to the rear window defogger grid. The HVAC control module houses the rear defog switch and also illuminates the rear defog indicator on the switch button, upon this request. Ground for the rear window defogger grid is provided by G301 for the Sedan or G302 For the Extended Sedan.

Rear Window Defogger System Components
The rear window defogger system consist of the following components:
• HVAC control module
• Body control module (BCM)
• DEFOG relay
• Rear window defogger grid
Rear Window Defogger Operation
When you turn the ignition to the ON position, ignition voltage is supplied to the DEFOG relay coil. Battery positive voltage is supplied at all times to the DEFOG relay switched input. When the rear window defogger switch is depressed, the HVAC control module illuminates the rear window defogger indicator and sends a class 2 message to the BCM. The BCM energizes the DEFOG relay by grounding the control circuit of the relay. This allows battery positive voltage from the relay switched input through the switch contacts and out the relay switched output to the rear window defogger. Ground for the rear window defogger is provided by G306 or G390 (crew cab).
When you turn ON the ignition and press the rear window defogger switch for the first time, the defogger cycle lasts 10 minutes. Further operation results in 5 minute defogger cycles.

Do you know what your messing with ? What's the problem ?

As by heat only works some of the time , you mean it doesn't blow air out of the vent's . This means you probably have a problem with the blower motor or blower motor resistor or blower motor relay .
Rear Window Defogger Inoperative

Exchange the rear defogger relay with a known good relay from the under hood junction block.
1. Turn the ignition switch to the ON position.
2. Press the rear defogger switch to the ON position.

Does the rear defogger grid warm?
--
Yes Go to Step 2
NO Go to Step 3

2

Replace the faulty relay.
Is the repair complete?
Go to Defogger System Check --

3

1. Use a fused jumper wire in order to backprobe between terminal A4 of underhood junction block connector C3 and ground.
2. Use a test lamp in order to backprobe between terminal C5 of underhood junction block connector C3 and ground.

Does the test lamp light?
--
Go to Step 4
Go to Step 23

4

1. Use a test lamp in order to backprobe between terminal C5 of underhood junction block connector C3 and ground.
2. Press the rear defogger switch to the ON position.

Does the test lamp light?
--
Go to Step 5
Go to Step 14

Switch, fuse or maybe the wiring to the window has come loose or off, happens alot, kits are available at local auto parts stores...
I hope that helps...

There is a module that controls the rear window defogger grid . LGM/ EGM Liftgate or endgate module .Receive's message on class 2 serial data network from the HVAC control module to turn it on when button pressed . Fuse # 3 30 amp located in the rear fuse box . Do you know where the rear fuse box is ?
Rear Window Defogger Description and Operation
Rear Window Defogger System Components
The rear window defogger system consist of the following components:
• HVAC control module
• Liftgate module (LGM)/endgate module (EGM)
• Rear window defogger grid
Rear Window Defogger Operation (With LGM)
Battery positive voltage is supplied through the LGM 2 fuse to the LGM for the rear window defogger system. When the rear window defogger switch is depressed, the HVAC control module illuminates the rear window defogger indicator, and sends a class 2 message to the LGM to enable the rear window defogger. The LGM enables the rear window defogger by allowing battery positive voltage to the rear window defogger.
When the rear window defogger switch is pressed for the first time, the defogger cycle lasts 10 minutes. Further operation results in 10 minute defogger cycles.
Rear Window Defogger Operation (With EGM)
Battery positive voltage is supplied through the EGM 2 fuse to the EGM for the rear window defogger system. When the rear window defogger switch is depressed, the HVAC control module illuminates the rear window defogger indicator, and sends a class 2 message to the EGM to enable the rear window defogger. The EGM enables the rear window defogger by allowing battery positive voltage to the rear window defogger.
The following conditions must be met for rear window defogger to operate:
• The end gate glass position is not below the index position.
• The window express down movement is not requested.
• The window down movement is not requested.
If the end-gate glass is not fully closed, the DIC displays "Tailgate Glass Down" when the rear defogger operation is attempted.
When the rear window defogger switch is pressed for the first time, the defogger cycle lasts 10 minutes. Further operation results in 10 minute defogger cycles.

Fuse Block - Rear
Beneath the left rear seat

check grids along rear window to check for broken lines and check wires on both sides of glass where connections are.