Need: Wiring Schematics for Rear Defroster/Defogger Button

[ragingfish]

Can anyone provide me with a wiring schematic for the rear defogger button?

Basically, I'm working on a project to heat the side windows in the coupe to melt ice and eliminate the indexing problem we're experiencing. I want to tie the heating system into the rear defogger button so one button triggers the rear window and door window systems...

Basically, I'm looking for anywhere I can tap into that system so that pushing the button will trigger my systems...

Thanks!!!

[TLS2000]

Uh, don't you need to be inside the car to push the button? In which case, why would you need to fix the indexing? I'm a little confused.

[ragingfish]

Uh, don't you need to be inside the car to push the button? In which case, why would you need to fix the indexing? I'm a little confused.

I think if you remote start, and the ambient temperature is below a certain point, the defroster is automatically triggered. I remote started yesterday, and when I got in, the rear window defroster light was on...as soon as I turned the key, it went out.

[TLS2000]

Ah.. I just happen to know absolutely nothing about the remote start system. What with the six speed manual and all...

[ragingfish]

Ah.. I just happen to know absolutely nothing about the remote start system. What with the six speed manual and all...

Ahh...true, true. I tend to be a bit remote-centric. I keep forgetting the manual guys get the shaft.

On another note, I have confirmed my theory!

If your vehicle has the remote start feature, the rear defogger will automatically be turned on if it is cold outside. The indicator light will be on. When the vehicle transitions out of the remote start mode, the rear defogger will turn off.

[jnak]

But if you have remote start, the regular defroster doesn't melt the windows for you?

[ragingfish]

But if you have remote start, the regular defroster doesn't melt the windows for you?

It can...but sometimes it's either not fast enough, or the ice and/or snow is too thick and it can't do it alone.

Plus, we're all assuming I would REMEMBER to set the mode knob to defrost the night before. What would be nice about this project is that, because the rear window defroster auto-senses cold weather and kicks in automatically, if I forget to set the mode knob the night before, I can still get into the car...

[EmersonHart13]

I wish I could help you as I am very interested in this project, good luck!

[e2helper]

Just to let you know how it works.

The switch in HVAC control head on base system sends a signal to the BCM. BCM drives relay in rear electrical center which activates the rear grid. The BCM is also the module that decides that it is cold enough to turn on the rear defog during a remote start (based on outside air temperature sensor).

The signal from the HVAC control head to the BCM is only a pulsed signal. One pulse to turn on and another to toggle off.

On automatic HVAC system this communication to BCM is done via a data bus and not a separate wire. However BCM still drives this relay in rear of vehicle.

[ragingfish]

Just to let you know how it works.

The switch in HVAC control head on base system sends a signal to the BCM. BCM drives relay in rear electrical center which activates the rear grid. The BCM is also the module that decides that it is cold enough to turn on the rear defog during a remote start (based on outside air temperature sensor).

The signal from the HVAC control head to the BCM is only a pulsed signal. One pulse to turn on and another to toggle off.

On automatic HVAC system this communication to BCM is done via a data bus and not a separate wire. However BCM still drives this relay in rear of vehicle.

So basically, I want to tap into the system at the relay, not at the button, right?

[e2helper]

Yes if you want something that is turning on at the same time as the rear defogger. However the rear defog fuse is pretty heavily loaded by the rear glass so you couldn't add much too it or you might blow fuse. On similar Malibu and Aura they have heated outside mirrors on same relay but use a different fuse. However you can't add that fuse to the G6 rear electrical center

[ragingfish]

Yes if you want something that is turning on at the same time as the rear defogger. However the rear defog fuse is pretty heavily loaded by the rear glass so you couldn't add much too it or you might blow fuse. On similar Malibu and Aura they have heated outside mirrors on same relay but use a different fuse. However you can't add that fuse to the G6 rear electrical center

That's not a problem. I planned to run an independent power source to the windows, but add in my own relay that would be triggered by the car relay to kick in at the same time...

Thanks man! You just made my day!

[ragingfish]

e2helper:

I know GM doesn't use a typical off-the-shelf relay like you'd find at radio shack. Are you able to tell me which pin on the defog relay in that trunk panel is the one with the output signal?

Thanks man!

[TLS2000]

Yes if you want something that is turning on at the same time as the rear defogger. However the rear defog fuse is pretty heavily loaded by the rear glass so you couldn't add much too it or you might blow fuse. On similar Malibu and Aura they have heated outside mirrors on same relay but use a different fuse. However you can't add that fuse to the G6 rear electrical center

I'm sorry, the Malibu has heated mirrors? And a strut bar if you get the SS. Where exactly do we see the benefit of spending $2-3000 more on an equivalent G6?

Do me a favour and pass this on to the marketing guys: Pontiac is supposed to be a more premium division than Chevy, and as such, should include better equipment in stock form than an equivalent Chevy.

Thanks.

[ragingfish]

phase 1 complete!

I was bored tonight so I ran all the preliminary wiring for my project.

Have a line running from the trunk power center to the front, wires from inside each door to the dash, and a new power line from the battery to the dash...

now all i need is my heating elements, wire 'em up, and we're gonna know for sure if my project is a success!