Hey all,
Possibly an obvious question but I'm stuck.
In the process of working all the electrics out so I can rewire it all (its a mess due to previous owners and various other possibly unrelated issues).
Electrics aren't my forte but I'm learning. I've come across a box that I can't work out what it is and what it's for. Pics below.
It has a bunch of wires going in the top(?) and then one big one coming out the bottom(?) which has a strange connector on the end, this was already unplugged and tucked somewhere so I can't trace what it was meant to go to.
Can anyone shed any light on this?

 

Well, the label says GUIDE which is a GM name for the Guide-Matic high beam dimmer. I'm guessing the group of wires goes to the headlight and/or dimmer switch and larger other connector may have been to the photocell (aka electronic eye).

 

Which year and model?

 

Good idea to include model and year of the car. In thread title would really help you get a better response.

 

Woops, forgot to write that in 1973 Custom Cruiser.
It has one of those eye things on top of the dash and the wire poking out isn't connected to anything either.
I believe that those kinds of things don't work very well here in England as we drive on the other side of the road. It was probably disconnected when it came over here, I'll try and trace the wires through to the front. I have a service manual so I'll check the wiring diagram for more process.
Thanks for all the info so far.

 

As pointed out by 4R5 it is a GM Guide-Matic (automatic) high/low beam dimmer. Introduced in 1952 by Oldsmobile & Cadillac as the Autronic Eye.

Perform some Internet searches of the name John Oldenburg who became a well-known repair person of these devices.

 

Good that it doesn't say Lucas on it...

 

There is no mention of automatically-dimming headlights as an option on any 1973 Oldsmobile. There is no mention in the dealer sales notebook, in any brochure, nor in the dealer specs book. The autronic eye/automatically dimming headlight option was a late 50s/early 60s thing.

The only headlight-related option on the full-size cars through the '70s was the "Twilight Sentinel, which was an adjustable timer at the headlight switch that would leave the headlights on for several minutes as you exited the car in some dark alley so that you would have some light while you were fumbling for your house keys.





If that mysterious box really is an auto headlight dimer, it might be some earlier owner's attempt to adapt something from an earlier car to this one.

 

Well, if as you say the dash has that eye thing then it is the Guide Matic. As stated above, it probably was added because as jaunty75 mentions, only the Twilight Sentinel was offered. Oh and jaunty75, the Twilight Sentinel was also to turn on your headlights when it was dark outside.
Yes, driving on the left side of the road would make it useless. I would carefully remove it and the eye, it might be worth something on eBay.

 

Irrespective of Oldsmobile availability &/or any particular model, it is a Guide-Matic Model No. 562 Serial No. 017021.
I consider John Oldenburg to have the most advanced knowledge pertaining to the Autronic, Guide-Matic & the Twilight Sentinel. The Twilight Sentinel was not a high/low beam dimmer but instead a device which automagically turned the headlamps ON/OFF based upon amount of daylight.

Supposedly, Guide-Matic devices were numbered as below. If correct, it would imply the device (above) was originally destined to be installed into a Cadillac?

156 000001 Chevrolet
256 000001 Pontiac
356 000001 Oldsmobile
456 000001 Buick
556 000001 Cadillac
6-- ---------- (The number 6 was GMC truck division and no automatic headlight dimming system was ever used in trucks.)
756 000001 Warranty Replacement
857 000001 Lincoln (An "A" will follow the serial number 1964 and up.)
864 000001-B Mercury
864 000001-C Ford

 

This is correct. I was mistaken above.

But the Twilight Sentinel was not offered in 1973. The only automated headlight control offered was "Nightwatch," and all it did was leave the headlights on for 60 seconds after the car was parked and turned off so you'd have some illumination as you walked to your front door at night.

This is from the 1973 Oldsmobile dealer album. Note that Nightwatch was offered only on the 98 and Toronado. Whatever the OP has in his '73 Custom Cruiser is something someone tried to add that was taken from another car. It is not factory.

I'm not sure what "Also accessory" means below. It was not an available accessory on any other '73 Olds, at least according to the '73 dealer specs book.







The Twilight Sentinel came later in the decade. I don't have the dealer albums for every year, so I don't know exactly which year it debuted, but I do have the dealer album for 1977, and it was offered that year. This is from the '77 album.

The Twilight Sentinel incorporated the features of the Nighwatch, and you now got three minutes instead of only 60 seconds.





Also note that, if you wanted the Twilight Sentinel, you also had to buy the Reminder Package, so you automatically got all of this as well.