1968 DeVille Headlight Switch

[thor375]

If you replace the standard '68 headlight switch with the Twilight Sentinel headlight switch will the system still work?   It seems to plug right in.

Thanx, Todd

[cadillactim]

The regular headlights will still work fine. The twilight sentinel has to have the rest of the components and wiring to work.

Tim

[Glen]

I don’t believe there is any difference in the switch, the difference is in the wiring harness. This seems to be supported by the master parts book. 

[Steve W]

I have twilight sentinel in my car. It’s never worked for me or the previous owner.  But the lights all work fine! So I’m guessing it’ll work just as well for you too.

[thor375]

To All,

Thank you for the info!  It's much easier to change out, now that the dash is out, rather than doing it in the car.  Might as well put the Sentinel switch in now, that way if I decide to do the whole system, the switch will already be in!

Ciao, Todd

[DeVille68]

How "hard" (or involved) is it to install a Sentinel Switch in a 68 DeVille with Autronic Eye?

I am thinking of adding the Sentinel. Does it use any components of the Autronic Eye or is it completely independent?

Best regards,
Nicolas

[69Deville]

It’s completely independent. You will need the updated switch, the photocell, and the amplifier. There is an NOS amplifier on eBay for $100. Didn’t see the photocell. I have one for a 69-70. Not sure if it can be repurposed for the 68. It’s a very easy install. The amplifier is what fails so an NOS one is a great option. I went through four on eBay before I found a fully functional one.

[bcroe]

The amplifier is what fails so an NOS one is a great option. I went through four on eBay before I found a fully functional one.   

It ought to be possible to repair a simple amplifier.  Bruce Roe

[cadillacmike68]

The actual headlight switch is the Same whether the car has Twilight Sentinel, Guide-Matic Auto dimming, neither, or both.

It is the extra rings and bezel markings that are different. Then of course are the actual components like sensors, and amplifiers, and wiring.

[cadillactim]

Actually there can be some differences in the basic headlight switch for Guidematic and TS. Some switches had an extra terminal for the option. I've seen some non optioned switches with the extra terminal and some without.

Also the main reason the TS fails is the photocell gets old and then the resistance is off. This is why the units say that the photocell and control box must be changed as a pair. Sometimes one gets lucky and a used photocell works with a different box, but oftentimes that does not work.

The control box has to be calibrated to the replacement photocell or the system will not work properly because the resistance values are off. To buy a NOS TS box without a matching photocell is a gamble, and even an old matched set may not work because the photocell may now not match the box because of age.

Another age related failure to the TS units (especially the 1964-70) is the capacitors go bad in the control box.

Tim

[cadillacmike68]

Tim,

My 68 did not have either. Cadillac made dealer sold option packs with either or both. I bought one way back (just TS), and you are supposed to not need a new switch, mine didn't need it. The kit also came with front bezels for just TS and for TS and GM, and the control rings.

I do know that 67 and 68 headlight switches are Not interchangeable, because of the parking lights side marker law that went into effect in 1968. In 67 there are No amber or red side marker lamps and the front parking lamps went off when you turned on the headlights!

Now of course my TS is on the fritz, probably (hopefully) the photocell  is just loose under the dash. It thinks it is always dark and keeps the lights on. I'm Hoping it's that.

[cadillactim]

Mike

I have seen switches with extra terminals in the late 60s. You are correct about 68 being different than the 64-67 switches. To see if your capacitors are bad in your box, turn the timer to max and see if the lights turn off right away or delay like they should. If little or no delay capacitors are bad.

Yes, if photocell has fallen down in dash with no light getting to it that will turn lights on.

Tim

[DeVille68]

So, if I have already the Autronic Eye, will I need to add a second photo cell?
How much work will a complete install of a Sentinental be?