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Discussion Starter #1 (Edited)
On my '82 Eldo the ported vacuum switch at the top rear of the engine (supplies vacuum for EGR, EFE, and something else), I think has an electrical connector on the back of it.

Trouble is, there's no wire going to the connector! Is the wire only used on some (later) engines/models? Is there a connector somewhere that should probably go to it?

I'm not sure if it's necessary to have it plugged in, or what it's function would be, or if it's even working right now being there's no wire going into it.

Can it work without the connector?? Anyone have any ideas??
 

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1) yes, there should be a connector on it. It is responsible for supplying the vacuum to operate the EGR, and

2) it may work without the connector which means no EGR operation, but your mileage and emissions are going to be affected by it.

IF you don't notice any problems with driveability/emissions then look for it, but don't worry about it....
 

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Discussion Starter #4
I think I heard it also controls the EFE (early fuel evaporation) valve, but does it switch between the two? I think the EGR still operates even without a wire going to the ported vacuum switch, but maybe I'll check to make sure..
 

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On my 1985 HT4100, it looks to be a 4 or 5 port vacuum switch. There are no electical connectors going to it. I have the entire motor out of the car and it is pretty easy to look at this. There is a "vacuum harness" that has 3 or 4 vacuum lines connected to it facing the front of the engine. Facing the rear of the block, a larger vacuum line is connected to it.

On any of the proted vacuum switches that I have seen, there aren't any electrical connectors. Just vaccuum lines that are controlled by the temperature of the coolant that comes in contact with the tip of the switch that screws into the water jacket.
 

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Discussion Starter #6
Ahh! Thanks for the info. Maybe I'll replace it anyway since its the original part.

On a side note, does your '85 come with daytime running lights (DRL)?

Thanks
 

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No DRls on my '85, just Twighlight Sentinel. I think that GM has some kind of module that splices into your wiring if you were to retrofit a DRL setup. This was a couple of years back around the time when GM was starting to put them on as standard equip. I'm sure there are other aftermarket setups now.
 

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Yes, the EGR is controlled by the ECM through that solenoid. The ECM will allow the EGR to operate when the system goes into closed loop.

DRL was first used in Canada on some 1989 Pontiac models, namely the 6000. Your car is likely equipped with Twilight Sentinal which will automatically turn on the lights when it gets dark. There is a photo cell just beside the lt front speaker that senses light. You can see it when you look through the windshield down. If this sensor circuit has become open, then it imitates a dark condition and the headlights will come on whenever the key is on.

There is a module that controls this. It's located under the lt hand side of the dash.

Mike
 
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