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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
You can see fuse, correct. With rear defogger turned on, use test light, see if any voltage at fuse or if fuse is blown? Also, check continuity on defogger grid, if no continuity, there is a break in the grid. If you can find the break, hopefully your local auto store has continuity paint that you can paint over the break to restore continuity.
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.
front or rear.?
my guess, wild is, the rear electric defogger, is dead.
the test is so easy.
attach any voltmeter to the 2 grid terminal. and turn the defroster on.
12v there? yes, then the grid is open.
no> the relay that feeds it is bad. (or its controls or FUSE is blown)
check all fuse first.
blinkers sounds like the flasher unit is not working. It's located under dash. Also check for burnt out bulbs.
Rear defrost, or rear defogger?: Your defogger for the rear window would run off a relay, probably located in the fuse panel of your car. Often, the connections at the rear window get broke or disconnected.
Front defrost: does your heater blower work?
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.
The rear defogger is fuse #14 (40 Amp fuse) in the underhood fuse box,no other fuses, I have the owners manual. If the fuse checks good test the heater grid of the rear defogger, it is most likely is an open circuit, it can be repaired by the dealer or u..
There are 3 fuses that control the rear defogger, and 1 relay
The fuses are: 10 amp HEATER, 10 amp MIRROR-HEATER; under the dash
The 30 amp DEF fuse is in the fuse box under the hood
The relay is the DEFOGGER relay, which is on the back side of the fuse panel under the dash
Also, check for a loose wire on the defroster grid (on the back glass), this is the most common problem.
check the clips...sometimes they do corrode. check if there is voltage present when you turn on the defogger. if there is voltage, then the defogger itself is faulty. it could just be a loose connection at the clip.
watch out, the clip is very hard to pull.
if there is no voltage, then trace the circuit , it could be a bad relay or fuse.
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