Hey, i kinda need some help troubleshooting my rear defogger... I looked up already a few posts about it, and i can confirm that the fuse and the relay are not to blame - and thats where the posts would normally end... But seeing as they are both fine in my car, i dont really know what else i could do! When i push the defogger button, the light comes on on top of it, but there is no load being put on my electrical system. When it was working fine, i could tell when i put the defogger on because my lights would dim... but now, nothing! Any help is greatly appreciated!

 

We have a rear defroster? What does the button look like LOL

 

LOL, tha'd be pretty nice!

 

mine was the same , look close at the relay one of the legs might have to be scuffed . cleaned mine up and works now

 

Seriously I didn't know we had a rearw defogger haha

 

I've had the same issue for a while, where is the relay located, cuz I've checked the fuse and that wasn't it haha

 

its that big square block above ur fuse, diagram located on the lid of ur fuse box

 

ah good call, thanks. now willing to help me with my 2.4 mani question :P since i see you have it installed

 

Bump - I still dont know what to look at!

 

1.Is the switch light coming on when you push the button( if not could be a bcm problem)
If yes the relay should be turning on(Located in fuse box under the hood along with the 40 amp RDFG fuse)
locate relay and have a buddy push the button - do you feel the relay come on.
If no replace relay
if yes 2.Check to see if you have 12 v at the rear defroster
remove both connector and check for voltage to ground(use a 12v test light or a multimeter.)one connector should have 12v if not check fuse

If the dfrost switch light is on and the relay is good you should be able to put the test light between the 2 connectors for the rear defroster AND IT SHOULD LIGHT UP.

if it lights up theres something wrong with the defroster on the glass ,probably damaged a connector cleaning the rear glass.
Take a good look maybe the connector just came off.



Heres some info
Rear Window Defogger Operation

Battery positive voltage is supplied through the RR DEFOG fuse, in the underhood fuse block, to the REAR DEFOG relay switched input. Ground for the REAR DEFOG relay is provided by G101. The BCM supplies 12 volts on the rear window defogger switch signal circuit to the HVAC control assembly. When you depress the rear window defogger switch, the rear window defogger switch pulls the signal circuit low. The BCM interprets as a request for the rear window defogger system. The BCM enables the rear window defogger system by supplying voltage to the REAR DEFOG relay coil. The relay coil supply voltage is also spliced off internally in the BCM to the supply voltage circuit of the rear window defogger indicator. The REAR DEFOG relay is energized and the rear window defogger indicator is illuminated. With the relay energized, battery positive voltage is allowed from the relay switched input through the switch contacts and out the relay switched output to the rear window defogger grid. Ground for the rear window defogger grid is provided by G403.

When you start the engine and press the rear window defogger switch for the first time, the defogger cycle lasts for 15 minutes. Further operation results in 7.5 minute defogger cycles. The rear defogger feature will not time out if vehicle speed is above 80 km/h (50 mph). The defogger cycle resets to 15 minutes when you cycle the ignition to the OFF position and then to the ON position.

 

I thought I posted this thread... I was quite confused there for a second

 

Hahahaha!

Thanks man. That bit of info really really helped me out. Funny part was, i followed your steps (i used a multimeter) and found out everything, theoretically, was working fine. Then i went to go retry out the defogger and the damn thing worked... I dont know what to say! It didnt work for 2 months and then suddenly it decides to work. I cant complain!

 

I also had no idea we had a rear defogger. LOL

 

mine hasn't worked for over a year lol.....fuse is good, relay is good.....just the connection came unsoldered on the rear window and im to lazy to fix it haha

 

Sorry to bring up an old thread, but my rear window defogger is not working either.

I checked with a multi meter. With the defogger on, I have 0 volts at the plug on the drivers side. Now if I pull the plug off the defogger and test the plug (meter grounded to chassis) it shows 12v on the plug. So I know I am getting current. As soon as I touch the plug onto the defogger, it shows 0v. Its like it is grounding out. I would think the fuse would blow if it was grounded out.

Any suggestions on what to check? The grid appears to be intact.

 

My rear window defogger was not working relay OK, fuse OK, ground on right side of window OK. I started to dig farther into the wiring and found a connector beside the left rear speaker under the deck lid inside the car was burnt. I cut an soldered the wire together for the rear window defogger and found it OK. There was 4 other wires on the connector they appear to be speaker wires they were OK so I left them alone. If you were using a multimeter to test for power it would say 12v when a load is on it it will go to 0v so check that plug I got at it without removing the headrest but its harder.