Rear Defroster Switch

[vangremlin]

Has anyone ever changed from the original push button style rear defroster switch to the later years toggle style?  I know the push button switch leads to a relay on the steering column, while the toggle style goes directly to the rear defroster.

The reason I'm interested in changing is because my defroster won't turn off on its own.  You have to turn the car off.  Does the toggle style turn off after a certain period of time, or at least allow you to toggle the switch to turn it off?  Thanks.

[eaglefreek]

I have the toggle version and my turns off by itself or you can turn it off manually.

[BenM]

I have not, but make sure you disassemble the new switch and lubricate it with silicone grease so the switch doesn't break off.

I may have the connector end for a switch laying around if you want it.

[vangremlin]

I have not, but make sure you disassemble the new switch and lubricate it with silicone grease so the switch doesn't break off.

I may have the connector end for a switch laying around if you want it.

Thanks for the tip.  The switch I have seems to operate pretty smoothly but an ounce of prevention makes sense.  The connector end you're referring to - you mean the pigtail that plugs into the back of the switch?  I have that also, but thanks for the offer.

[JayRamb]

My switch turns off around 10-12 minutes. I have an 87.

[BenM]

Thanks for the tip.  The switch I have seems to operate pretty smoothly but an ounce of prevention makes sense.  The connector end you're referring to - you mean the pigtail that plugs into the back of the switch?  I have that also, but thanks for the offer.

That's what I meant. I went through three before I realized how easily they come apart. The first really cold day when it didn't bind was nice.

[carnuck]

There is a timer in the relay of later ones. Earlier ones didn't have it.

[vangremlin]

Thanks everyone for your responses.  Sounds like thats the way I want to go, now I just need to figure out how to change the wiring from the old relay to the new switch.

[vangremlin]

I dug into this a little bit more.  Seems pretty straightforward.  The 81 version is pretty basic, you have the switch, which triggers the relay, which goes to the rear window defroster and the small indicator light in the radio bezel.  In the newer version, the relay is housed with the switch, and the light is built into the switch also.  The only question I'm coming up with is that there is a light blue wire (14 ga) that shares the same terminal coming out of the switch as the light blue wire (16 ga) that goes to the rear window defroster.  The attached schematic from the Eagle Nest download section shows the 14 ga wire going to a diode, and then on to P9.  Since the original switch didn't control anything else, I figure that I don't really need to worry about this 14 ga wire.  Anybody have any different thoughts?  Thanks.

http://www.amceaglenest.com/images/Downloads/Rear%20Window%20Defogger.jpg

[BenM]

I believe that diode is part of the famous "Diode Trio" that triggers high idle when the defroster, headlights, or air conditioner is on. It's under the hood and part of the harness somewhere. I don't know offhand if they were used pre-computer.

[vangremlin]

Thanks.  I've switched over to Gronk's Motorcraft carb so I guess it wouldn't come into play any longer, even if it was there to begin with.

[ammachine390]

I believe that diode is part of the famous "Diode Trio" that triggers high idle when the defroster, headlights, or air conditioner is on. It's under the hood and part of the harness somewhere. I don't know offhand if they were used pre-computer.

On 81 models, the idle speed control was different than the later years. The diode pack is not part of the harness. There is another box that looks like a smaller ignition module in the back of the engine compartment on the passenger firewall that is labeled "idle speed control." That box is the diode pack. All 81 models had, whether or not they had the computer, as they were separate systems. Also on 81 models, the idle speed did not increase when the headlights were turned on, that started in on 82 models. The other thing that raised the idle speed on 81 models (possibly later models too, not sure) was if you turned the steering wheel to one side all the way, not exactly sure how that triggered a higher idle speed though.

Anybody else's Eagle, that's not an 81, raise the idle speed for steering turned all the way to one side?

The reason I'm interested in changing is because my defroster won't turn off on its own.  You have to turn the car off.  Does the toggle style turn off after a certain period of time, or at least allow you to toggle the switch to turn it off?  Thanks.

Mine doesn't either. I pulled the relay apart to look inside it, found nothing that really looked abnormal though.

[vangremlin]

Thanks for the info ammachine 390.  I've got that idle speed control box on mine.  I guess its just dead weight now that I've Gronked my car!

[BenM]

Thanks for the info ammachine 390.  I've got that idle speed control box on mine.  I guess its just dead weight now that I've Gronked my car!

You could pick up an idle solenoid that fits the 2100 series and install it. That's all it should need.

I'm fairly certain that the later Eagles did not change idle based on power steering, but the computer did monitor idle speed and could use the vacuum part of the sol-vac to force open the throttle if it dropped too low.

I would expect a pressure sensor mounted on the high pressure hose if that was used to control idle.

[carnuck]

I believe that diode is part of the famous "Diode Trio" that triggers high idle when the defroster, headlights, or air conditioner is on. It's under the hood and part of the harness somewhere. I don't know offhand if they were used pre-computer.

On 81 models, the idle speed control was different than the later years. The diode pack is not part of the harness. There is another box that looks like a smaller ignition module in the back of the engine compartment on the passenger firewall that is labeled "idle speed control." That box is the diode pack. All 81 models had, whether or not they had the computer, as they were separate systems. Also on 81 models, the idle speed did not increase when the headlights were turned on, that started in on 82 models. The other thing that raised the idle speed on 81 models (possibly later models too, not sure) was if you turned the steering wheel to one side all the way, not exactly sure how that triggered a higher idle speed though.

I took the idle speed box off mine. Since I plan to go EFI then liquid propane injection later I didn't need it or the cat.

Anybody else's Eagle, that's not an 81, raise the idle speed for steering turned all the way to one side?

Only 4 cyls had that AFAIK. It's a pressure switch on the power steering high pressure hose.