Mystery bulb socket

[ronald b. kazi]

Behind the insturment panel I found a bulb socket about 1" in diameter
that holds a wedge type bulb which has four wires (red, green, black and
white) of small guage going to a connector which changes to the same
color but a heavier guage. The socket has a small circular printed
circuit inside. It doesnt seem to light when I turn on the dash
lights. I don't remember it being in the dash when I pulled it out,
though that was several months ago. The wires definately are part of the
wiring harness. Cant see any such gizmo on the wiring diagrams
(73)...any ideas?

Ron and Julie
73 Painted Desert

 

[john szalay]

>Behind the insturment panel I found a bulb socket about 1" in diameter
>that holds a wedge type bulb which has four wires (red, green, black and
>white) of small guage going to a connector which changes to the same
>color but a heavier guage. The socket has a small circular printed
>circuit inside. It doesnt seem to light when I turn on the dash
>lights. I don't remember it being in the dash when I pulled it out,
>though that was several months ago. The wires definately are part of the
>wiring harness. Cant see any such gizmo on the wiring diagrams
>(73)...any ideas?
>
>Ron and Julie
>73 Painted Desert
>
>

Ron
I checked out the dash panel on our 73 PD ( Early production model
Serial 51 produced in Feb 73)
And I don,t see anything that looks exactly like that, the only thing
that comes close is located on the left side of the dash and it is the
the fiberoptic unit that supplies light to the flat legend panels on the
headlight switch and the windshield wiper control.
it has a black and a white wire into the bulb socket and a flat ribbon
cable out the other end. the flat ribbon is the fiberoptic cable on our
model, I'm not sure if the later models went to single leads .

Check to see where those "wires" of yours are going, if they go to the
flat label or legend panels. then thats the lighting fiberoptics.

I know that Cadiliac used single lead fiberoptics for their telltail
light indicators. Those showed the dirver if their lights were working.

John & Brenda Szalay
73 Painted Desert ( used to be anyway)

 

[ronald b. kazi]

I removed the fiberoptic stuff and it could be that. It just seems strange that
I have four small wires and some sort of PC board inside. Seems unlikely that an
aftermarket item would have matching wires in the wiring harness.

Ron and Julie
73 Painted Desert.

> >Behind the insturment panel I found a bulb socket about 1" in diameter
> >that holds a wedge type bulb which has four wires (red, green, black and
> >white) of small guage going to a connector which changes to the same
> >color but a heavier guage. The socket has a small circular printed
> >circuit inside. It doesnt seem to light when I turn on the dash
> >lights. I don't remember it being in the dash when I pulled it out,
> >though that was several months ago. The wires definately are part of the
> >wiring harness. Cant see any such gizmo on the wiring diagrams
> >(73)...any ideas?
> >
> >Ron and Julie
> >73 Painted Desert
> >
> >
>
> Ron
> I checked out the dash panel on our 73 PD ( Early production model
> Serial 51 produced in Feb 73)
> And I don,t see anything that looks exactly like that, the only thing
> that comes close is located on the left side of the dash and it is the
> the fiberoptic unit that supplies light to the flat legend panels on the
> headlight switch and the windshield wiper control.
> it has a black and a white wire into the bulb socket and a flat ribbon
> cable out the other end. the flat ribbon is the fiberoptic cable on our
> model, I'm not sure if the later models went to single leads .
>
> Check to see where those "wires" of yours are going, if they go to the
> flat label or legend panels. then thats the lighting fiberoptics.
>
> I know that Cadiliac used single lead fiberoptics for their telltail
> light indicators. Those showed the dirver if their lights were working.
>
> John & Brenda Szalay
> 73 Painted Desert ( used to be anyway)

 

[darren paget]

IIRCthe pc board has to do with the low coolant warning light in the warning light
cluster. Not 100% sure but pretty close. Darren

> I removed the fiberoptic stuff and it could be that. It just seems strange that
> I have four small wires and some sort of PC board inside. Seems unlikely that an
> aftermarket item would have matching wires in the wiring harness.
>
> Ron and Julie
> 73 Painted Desert.
>

>

> > >Behind the insturment panel I found a bulb socket about 1" in diameter
> > >that holds a wedge type bulb which has four wires (red, green, black and
> > >white) of small guage going to a connector which changes to the same
> > >color but a heavier guage. The socket has a small circular printed
> > >circuit inside. It doesnt seem to light when I turn on the dash
> > >lights. I don't remember it being in the dash when I pulled it out,
> > >though that was several months ago. The wires definately are part of the
> > >wiring harness. Cant see any such gizmo on the wiring diagrams
> > >(73)...any ideas?
> > >
> > >Ron and Julie
> > >73 Painted Desert
> > >
> > >
> >
> > Ron
> > I checked out the dash panel on our 73 PD ( Early production model
> > Serial 51 produced in Feb 73)
> > And I don,t see anything that looks exactly like that, the only thing
> > that comes close is located on the left side of the dash and it is the
> > the fiberoptic unit that supplies light to the flat legend panels on the
> > headlight switch and the windshield wiper control.
> > it has a black and a white wire into the bulb socket and a flat ribbon
> > cable out the other end. the flat ribbon is the fiberoptic cable on our
> > model, I'm not sure if the later models went to single leads .
> >
> > Check to see where those "wires" of yours are going, if they go to the
> > flat label or legend panels. then thats the lighting fiberoptics.
> >
> > I know that Cadiliac used single lead fiberoptics for their telltail
> > light indicators. Those showed the dirver if their lights were working.
> >
> > John & Brenda Szalay
> > 73 Painted Desert ( used to be anyway)

- --
Darren Paget
76 Experimental
Another Fab Day
http://www.TZEplus.com

 

[john szalay]

>IIRCthe pc board has to do with the low coolant warning light in the
warning light
>cluster. Not 100% sure but pretty close. Darren
>
>

But was that an option on a 73 coach ? mine has the low fuel light but
not the low coolant.

 

[ronald b. kazi]

I notice on my glovebox sticker the following RPO:
C96301 WARNING LT HD BRAKE&LO
Could this be a clue? Is it an optional warning light to tell me that
something is "LO".
Would go out and tracet the wires but it is cold and I have Bronchitis.

Ron and Julie
73 Painted Desert

> >IIRCthe pc board has to do with the low coolant warning light in the
> warning light
> >cluster. Not 100% sure but pretty close. Darren
> >
> >
>
> But was that an option on a 73 coach ? mine has the low fuel light but
> not the low coolant.

 

[ronald b. kazi]

The round bulb socket that I found with the circuit board on the back
appears to be the Low Fuel circuit.

1)Is there a bulb that goes in it?
2)Where does it mount? It seems to fit in the small hole between the
two guage clusters on the metal instrument panel backing plate. There
is no corresponding hole on my original instrument panel plastic front
plate. Is my plastic panel not original?
3) How do I test it?
4) I remembers seeing someone that had a replacement circuit drawing on
the web. Am I dreaming?

Thanks in advance for your help.

Ron and Julie
73 Painted Desert

 

[peter brandt]

Ron,

Horst H. Becker makes and sells replacement circuit boards for low fuel,
coolant and other indicators. He's not on GMCnet, his e mail address is
horstb

Peter
77 Eleganza II
Colorado

- ----- Original Message -----
From: "RONALD KAZI"
To: "GMC"
Sent: Saturday, March 04, 2000 12:41 PM
Subject: GMC: Mystery bulb socket

> The round bulb socket that I found with the circuit board on the back
> appears to be the Low Fuel circuit.
>
> 1)Is there a bulb that goes in it?
> 2)Where does it mount? It seems to fit in the small hole between the
> two guage clusters on the metal instrument panel backing plate. There
> is no corresponding hole on my original instrument panel plastic front
> plate. Is my plastic panel not original?
> 3) How do I test it?
> 4) I remembers seeing someone that had a replacement circuit drawing on
> the web. Am I dreaming?
>
> Thanks in advance for your help.
>
> Ron and Julie
> 73 Painted Desert
>
>
>

 

[ronald b. kazi]

Figured out how to test the low fuel light. I grounded the wire that runs
from the sender to the fuel selector switch, either one will do as long as
the switch is in the right direction.. It looks as if the low fuel switch
determines when the sender is fully grounded (or close to it), then turns on
the light. This still doesn't tell me where the bloody light goes, I will
have to drill another hole in my new dash. I have yet to determine if the
sender will send the right info to the low fuel switch. I guess I have to
get the engine running first in order to run down the tanks.

Ron and Julie
73 Painted Desert

> Ron,
>
> Horst H. Becker makes and sells replacement circuit boards for low fuel,
> coolant and other indicators. He's not on GMCnet, his e mail address is
> horstb
>
> Peter
> 77 Eleganza II
> Colorado
>
> ----- Original Message -----
> From: "RONALD KAZI"
> To: "GMC"
> Sent: Saturday, March 04, 2000 12:41 PM
> Subject: GMC: Mystery bulb socket
>
> > The round bulb socket that I found with the circuit board on the back
> > appears to be the Low Fuel circuit.
> >
> > 1)Is there a bulb that goes in it?
> > 2)Where does it mount? It seems to fit in the small hole between the
> > two guage clusters on the metal instrument panel backing plate. There
> > is no corresponding hole on my original instrument panel plastic front
> > plate. Is my plastic panel not original?
> > 3) How do I test it?
> > 4) I remembers seeing someone that had a replacement circuit drawing on
> > the web. Am I dreaming?
> >
> > Thanks in advance for your help.
> >
> > Ron and Julie
> > 73 Painted Desert
> >
> >
> >

 

[john szalay]

>Figured out how to test the low fuel light. I grounded the wire that runs
>from the sender to the fuel selector switch, either one will do as long as
>the switch is in the right direction.. It looks as if the low fuel switch
>determines when the sender is fully grounded (or close to it), then turns on
>the light. This still doesn't tell me where the bloody light goes,

On our 73 the low fuel light is one the large red panels near the battery
switch. I would have to go out to the coach to see which one of the two it
is... ( large being 3/4" by 1") approx.

 

[ronald b. kazi]

I have the same telltale on my panel. The "switch" which houses the circuit has
what apears to be a light socket on it. The unit is about 1" in diameter and has
a 5/8" round clip that looks like it fits in a hole an holds a wedge type bulb.
The circuit has the following connections:

1) Positive power (ignition)
2) Ground
3) To aux fuel switch
4) To telltale light.
Cant understand the socket, unless it is some sort of fuse holder...

Ron and Julie

> >Figured out how to test the low fuel light. I grounded the wire that runs
> >from the sender to the fuel selector switch, either one will do as long as
> >the switch is in the right direction.. It looks as if the low fuel switch
> >determines when the sender is fully grounded (or close to it), then turns on
> >the light. This still doesn't tell me where the bloody light goes,
>
> On our 73 the low fuel light is one the large red panels near the battery
> switch. I would have to go out to the coach to see which one of the two it
> is... ( large being 3/4" by 1") approx.

 

[ronald b. kazi]

I dont know if it did. If it did, it doesnt now. I fried it trying to resolder a loose connection with my 4kw 440Volt soldering iron. (only slight exageration).

I am contacting Horst to get a new sensor.

Ron and Julie

> Ron - if you check the maintenance manual there is a good description of this control unit. There are 4 leads coming out of it. One goes to a bulb that is in the telltale light cluster. The circuit board unit will light the low fuel bulb when the signal from the fuel sending unit reaches a predetermined level. It is not adjustable. I haven't had one apart but if there is a bulb in it it must operate a photoelectric cell to trigger the circuit. Does you low fuel light work?
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM