Rare 1970 Headlight Warning Diode

[Cuda Cody]

@screamindriver  this is some super detailed and awesome info!!!!     The A01 light package is hard for me to understand sometimes and you just made it a lot easier.   

[fc7cuda]

@screamindriver  this is some super detailed and awesome info!!!!     The A01 light package is hard for me to understand sometimes and you just made it a lot easier.   

That's a great break down of this feature.   

[screamindriver]

Here's a schematic of the wiring for the headlight delay relay if anyone wants to add/reinstall the option...

[cataclysm80]

For those who want to add it, is there a modern equivalent of the relay available at local parts stores?
Even if it doesn't plug directly into the original wiring connector, we could still wire it up.

[71GranCoupe]

The option requires it's own sub-harness to power the relay...The dash also gets a notice near the headlight switch...So how it works is you shut the vehicle off but leave the headlights on....Now when you turn off the headlight switch the lights stay on for approximately 30 seconds then automatically turns themselves off...Pretty common by today's standards but state of the art in 1970...I can pull in the shop and have some lights for half a minute to get situated...    Here's a pic of the engineering drawing showing the location on the inner,left kickpanel area....And a pic of an original notice sticker on an E body dash...{Just an FYI..ECS makes that notice sticker}

Yours us only the 2nd car I have ever seen with that option on. Cool. Do you know if that sticker was an oem thing? I am going to have to get that sticker, even if it isn't oem, I like it. 

[cataclysm80]

Pretty sure that sticker is OEM.

[71GranCoupe]

Pretty sure that sticker is OEM.

Thanks!! Do you know if it is coded on the BS, or is it combined with an option group? 

[cataclysm80]

Thanks!! Do you know if it is coded on the BS, or is it combined with an option group? 

I believe it's only available as part of the A01 Light Package.

[cataclysm80]

Looking at the wiring diagram for the Headlight Delay, I've always had a difficult time understanding how it works.
Most relays I've worked with have a trigger wire which activates the relay (could be activated by either power or ground, depending on how it's wired).  It's basically a simple switch allowing a trigger signal from a small wire to "turn on" (connect) another circuit.
I could see how the Headlight Delay relay would be activated and power the headlights, but had trouble grasping how it would shut them off after 30 seconds.   I didn't understand why the trigger signal which activated the relay would cease to exist 30 seconds later. 
What would possibly change 30 seconds after you left the car that would shut off the lights?


After reading up on the ignition switch time delay, I think I finally understand. 
The time delay relay isn't a typical relay that activates and deactivates with the application and removal of a trigger signal.  Instead, it functions more like a turn signal flasher.  Once triggered, it is on for a short time and then shuts off until triggered again. 
A turn signal flasher is immediately retriggered until the turn signal lever is cancelled.
The headlight delay is triggered by turning the lights off after the ignition.
The ignition switch delay is triggered by the door jamb switch.



The following info was provided by Jim at JS Restorations.  He specializes in E body electrical stuff.
(definitely the go to guy for repairing your dash light dimmer switch, since he had stainless resistor coils made and they won't corrode and quit like the originals do.)

The ignition time delay relay does power the light fixture on the steering column for the ignition switch, the title light fixture (switch panel) and also the map light fixture.
Think of this time delay relay as operating like a one shot turn signal relay. Both relays work by stainless steel contact arms where one is wound with a wire coil. As heat builds up, these contacts heat up, bend and close, then when power is cut, the arm cools and disconnects.
The difference is the time delay relay will turn on when a door is opened and continues to light those three bulbs after the door closes and does not re-trigger, but only continues on one time for about thirty seconds. Once the door opens again, this sequence starts over again.
The ignition light delay relay should be mounted on the steering column with tape as they did at the factory. This serves as a heat sink since this is a thermal driven device. Hanging in mid air can cause this device to burn up rather quickly.
To test this relay, unplug and read the impedance between the 12 volt battery input and door jam ground terminals. It should read around -35 Ohms. If there is an O/L reading, the part is dead. Once plugged back in and the door opened and closed, the output terminal should read 12 volt between it and any clean exposed dash metal for a ground.

[screamindriver]

Here's a view of the internal components... 12v is constant from the battery...Door jamb switch completes the circuit heating up the windings...

[cuda hunter]

Great thread!   

[Cuda Cody]

In case anyone needs one, I just found a NOS E body headlamp delay relay in my stash of parts. 

[0cha]

Do you still have this relay? Thanks

[0cha]

Do you still have this relay? Thanks

[anlauto]

Try @Cuda Cody