Defogger Problem with 2007 Vibe

[Foundryrat]

Just bought a 2007 base Vibe with about 120,000 miles on it. The rear window defogger comes on when you start the car, regardless of the switch position, and stays on ignoring the switch and the supposed 15 minute shutdown. And, yes, the defogger is getting hot. It might be the switch, or a stuck relay, but since it was 106 today here in Phoenix I thought I would just pull the relay and shut it down for now. So, how do you open the blue box under the dash next to the fuse box?

Thanks in advance.

[Derf]

Are you getting any voltage across the coil legs of the relay socket? Might be the switch. Is their a similar size relay in the panel that you can temporarily substitute to see if the relay was stuck? Not sure of any other functions in the vibe that cause the rear defroster to come on, believe only manually pressing the switch can turn the defroster on.

[Foundryrat]

Thanks, Derf! It sure could be the switch, but for now I just need to find out how to get the relay box open. Do you have any tips or leads on that? Regards,

[joatmon]

I don't know what blue box is under the dash next tot he fuse block, but I'm pretty sure you don't need to open it.

The defog relay is on the top side of the fuse block. You should be able to get it it by removing the storage bin left of the steering wheel, and (independently) by pulling out the trim panel on the left of the dash that has the dimmer, mirror control and air vent. This pic was uploaded to show the location of the starter relay (marked by a red arrow). In the pic, the defog relay is just below the starter relay.



The top of the pic is the left side when looking in through the removed dash trim, so actually, the starter relay is on the left side, the defog relay is just right of it.

On mine, the starter relay and defog relay are different colors, so they may be different part numbers, but from the drawing it looks like they have the same socket, so they may be interchangeable

From the wiring diagram, it looks like there is circuitry in the defog switch, it looks like whatever should be turning the defogger off after 15 minutes should be inside the switch. Doesn't mean it's the switch or the relay, at this point it could be either. The relay could be stuck closed ignoring the switch, or the switch could be commanding the relay to always close.

It's relatively easy to remove the trim around the radio, I usually pull the bottom edge out, pivot it up a little then wiggle it to clear the top clips. One test to identify if its the switch or the relay is to pull the radio trim out, and disconnect the wiring connector from the defog switch and turn the key to run position. If the defogger still comes on, then it is the relay, if the defogger doesn't come on then its the switch. One caveat,theoretically it could be some much more unlikely short in the wiring independent of the switch and the relay, but as I said, much more unlikely.

[Foundryrat]

Thanks joatman. I finally managed to check things out and disconnecting the switch has stopped the defogger heating. I'll deal with the rest of it next month when we cool off some more here in AZ. BTW Brandon Gray has posted a nice video on how to pull various trim pieces from the dashboard. https://www.youtube.com/watch?v=ECHAoRYZXJY It's amazingly easy to do compared to some other autos.

[Foundryrat]

Installed new switch in 10 minutes and fixed the problem.