Headlight dimmer switch 1978 Eldorado

[dennisspeaks]

When I did the inspection before purchasing last week I noticed the driver's door light didn't come on, the driver's rear lights didn't come on and when I pressed the hi/lo dimmer switch all lights came on but wouldn't stay on.   My switch has the three prong plus one extra wire.  I have tried to find them online and have no luck yet.

I also noticed this has two switches inside the door jam, which is for the lights upper or lower?  What is the other switch for?

Thanks

Dennis

[The Tassie Devil(le)]

G'day Dennis,

The second switch is for the Automatic Seat Back Release.

The two door cars have a solenoid that operates when the door/s are opened, which releases the seat back lock, enabling passengers from the back to enter or egress without having to reach down and operate the never manually.

Bruce.

[TJ Hopland]

The extra wire on the dimmer switch is part of the Guide-Matic system which when engaged uses a sensor to sense oncoming lights and turn off the highbeams.   Electrically its a much more complex than a typical system.  The lights are actually controlled by relays.  You really need the manual and the diagram to troubleshoot the system.   

[dennisspeaks]

That be the 1978 Fisher Body Shop Manual?

[The Tassie Devil(le)]

Yes.   But electrical is in both that and the Shop Manual.

The Shop Manual covers just Cadillac, but the Body Manual covers all GM Cars for that year.   You just have to sort out in each section for what you want.   They go by the Body Code numbers and Model Letters for Series designation.

Bruce.

[dennisspeaks]

Bruce, I was wondering what that noise was.  Lots to learn about these cars.  Thanks for the info.

e Tassie Devil(le) link=topic=161675.msg474123#msg474123 date=1598926746]
G'day Dennis,

The second switch is for the Automatic Seat Back Release.

The two door cars have a solenoid that operates when the door/s are opened, which releases the seat back lock, enabling passengers from the back to enter or egress without having to reach down and operate the never manually.

Bruce.
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