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Button mounted on intake manifold


Guest Ansis42

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Guest Ansis42

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[TD=width: 100%]Hello all,

I am working on replacing the head gaskets on my old 1980 Buick. While on this adventure, I stumbled upon a curious little black button. This button is attached to a bracket, which is mounted on top of the intake manifold. I've attached a picture of this button. Anybody know what this button does (and don't tell me to "push it and find out", smart-asses). It is a 1980 Buick Lesabre, with the Pontiac-built 4.9L 301 cubic inch engine. Any help would be greatly appreciated. Thanks![/TD]

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Guest WEB 38
Does not look like anything that I have seen on a factory vehicle. Might be some sort of aftermarket product like a theft deterrent ???? Just guessing.

Maybe its for when you fall down and cant get up?

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more than likely, it is a transmission related switch, like a kickdown switch. charles coker, 1953 pontiac tech advisor.

Not in the 1980 models. None of the transmissions offered in the LeSabre that year behind the 301 used an electric kickdown (the TH200 used a cable-actuated throttle valve and the TH350 used a cable-actuated kickdown). A better photo would help. The connector appears to be a Packard 56 series connector, so it looks like a factory installation, but I've never seen an underhood pushbutton since the ill-fated federally-mandated seat belt interlocks in 1974-75 (there was a one-time defeat pushbutton under the hood on those cars).

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Guest Ansis42
Not in the 1980 models. None of the transmissions offered in the LeSabre that year behind the 301 used an electric kickdown (the TH200 used a cable-actuated throttle valve and the TH350 used a cable-actuated kickdown). A better photo would help. The connector appears to be a Packard 56 series connector, so it looks like a factory installation, but I've never seen an underhood pushbutton since the ill-fated federally-mandated seat belt interlocks in 1974-75 (there was a one-time defeat pushbutton under the hood on those cars).

Well, I can take another picture for you, but the picture you see literally shows almost everything. It is simply a black button that is attached to a metal bracket, and that bracket is bolted on top of the intake manifold. 2 green wires go into the button (one light, one dark). I haven't traced the wires yet, but I can certainly try that and see where they lead. I'll try to get a close-up of the button for any text or codes that may be on it.

Edited by Ansis42 (see edit history)
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It is likely a throttle actuated microswitch and likely actuated at idle. I haven't tried to research it on a wiring diagram but the light green and dark green wires are a clue also. I will bet it is on your schematic. Your carburetor or linkage may not be original.

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Could it be some sort of a timing advance-defeat switch so that the timing can be set without a computer moving the timing around? Pretty much just guessing here, but I see a distributor in the background, and no linkage anywhere near the switch.

The switch looks like it's meant to be actuated by a person's finger, not by linkage.

Most throttle activated switches I'm familiar with have a hinged metal lever over the actuation button of the switch, for both wear resistance and to allow a lot of linkage movement without damaging the fairly fragile microswitch..

Greg L

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Well, I can take another picture for you, but the picture you see literally shows almost everything. It is simply a black button that is attached to a metal bracket, and that bracket is bolted on top of the intake manifold. 2 green wires go into the button (one light, one dark). I haven't traced the wires yet, but I can certainly try that and see where they lead. I'll try to get a close-up of the button for any text or codes that may be on it.

Well, for example, where was it installed originally? Was it simply bolted to the intake with the button pointing straight up? Does the bracket even look like something GM built, or does it look aftermarket? Those things cannot be seen in the small photo you posted.

Edit: OK, here's another picture of a 301, and it appears to be a throttle actuated A/C compressor cutout switch. The throttle arm on the carb has a lever that sticks out and depresses the button at WOT. The A/C compressor clutch cutout switch deactivates the A/C compressor for slightly more passing power. That pavement-ripping 301 needs all the help it can get...

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Edited by joe_padavano
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Guest Ansis42
Well, for example, where was it installed originally? Was it simply bolted to the intake with the button pointing straight up? Does the bracket even look like something GM built, or does it look aftermarket? Those things cannot be seen in the small photo you posted.

Edit: OK, here's another picture of a 301, and it appears to be a of throttle actuated A/C compressor cutout switch. The throttle arm on the carb has a lever that sticks out and depresses the button at WOT. The A/C compressor clutch cutout switch deactivates the A/C compressor for slightly more passing power. That pavement-ripping 301 needs all the help it can get...

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You're a genius! I normally try to find answers on my own, but sometimes asking someone with a little more knowledge is MUCH more helpful than Google. I appreciate the insight. This switch might be useful if my A/C actually worked :(

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You're a genius! I normally try to find answers on my own, but sometimes asking someone with a little more knowledge is MUCH more helpful than Google. I appreciate the insight. This switch might be useful if my A/C actually worked :(

Please tell this to my ex-wives... :eek:

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Does it have aftermarket A/C? I do not ever remember seeing that on an original car...

The OEM carb throttle lever has an extension that exactly presses on the button at W.O.T., so I'm thinking it's factory. Oldsmobile used a similar W.O.T. cutout switch, but Olds mounted it on the accelerator pedal under the dash instead of on the intake manifold.

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