R1234

Hi all,
Can someone enlighten me on how the early 68's seat belt push button located in the center guage cluster bezel is set up and how it's supposed to work. My AIM is not real clear on this. I know the right side of the bezel is used for door ajar warning light. Since mine is a early 68 it does not have the wiper over ride cut out in the bezel.
Thanks

JmpnJckFlsh

68rdstr, my experience and reference literature for 68 is limited, but maybe my reply will get some discussion by 68 owners going.

If the 68 seat belt warning light is like the 70s, the light comes on when the ignition is turned on and it remains lit until the seat belt warning light reset button is pushed. It is simply a reminder light and has no sensors or switches to cancel its action, or a warning buzzer like later years.

So, it is generally a PITA; every time you start the car, whether you have your seat belt on or not, that freakin' light comes on and you have to reset it to get that annoying light to go off. As soon as my car is through with its judging career, that sucker is going to be disabled to prevent wearing the paint off the cluster face.

On the 70, there is no wiper over-ride switch on the center cluster. All the over-ride controls for the wipers are under the steering column; there is a round **** in the center flanked by two pull down ***** on either side. You pull down on the rubber **** on the right to over-ride the wiper door system open the wiper door, and turn the center **** (over-ride switch) to operate the wipers. The left pull down **** over-rides the headlight door open system to open the headlight doors. This may be a change from 68, and I am unaware of the change.


[Modified by Chuck Sangerhausen, 12:36 PM 9/4/2001]

Easy Mike

Chuck is correct; the selt belt warning on the '68s is a reminder only; there is no electrical connection of any type to the actual seat belts. My car hasn an April build date. The seat belt warning is on the left side of the center cluster. There is a small printed circuit on the back of it and it takes a bayonet type lamp. The lamp I am currently using is acutally a Ford Pinto dash illumination lamp. It works like a charm in my Seat Belt Warning light.

R1234

So, how does the push button's coil receive it's power? Where is the connection to the wiring harness made? Is it from the fuel guage? I have a black wire running from one fuel guage terminal to a terminal on the push button's coil. The fuel guage harness connection are pink and tan. Is the black jumper a power connection or a ground?


[Modified by 68rdstr, 3:42 PM 9/4/2001]

JmpnJckFlsh

I fer sure don't have a wiring diagram, but I am fairly certain there has to be a relay in the circuit. There is likely to be a relay holding the contacts to the light closed until you interrupt the relay power by pushing the button. My feeling is the black wire you see from the fuel gauge to the push button is a ground, since black is usually used by GM for grounds.

R1234

Chuck,
My bad, I made a mistake, upon closer examination of the wiring diagram the fuel guage has a pink and tan wire connected to it. The pink wire goes to the fuse block. It also is spliced to the park brake lamp's pink wire. The tan wire from the fuel guage goes to the rear harness connecter. I can't find any reference to the seat belt push button's black jumper. One other thing the black jumper is connected to the terminal that has a raised piece of metal in the middle of the terminal blade. Is the reason for this is to make sure the connector is plugged into the wiring harness correctly?

JmpnJckFlsh

68rdstr, you have forced me to scour my 70 wiring diagram, and the only thing that I have been able to confirm is that, yes, the fuel gauge DOES have a pink and tan wires going to it.

Sheesh...I can't even find that stupid seat belt circuit...It's like it doesn't even exist! You need a REEL 68 expert. If you find the answer, please let us electrically challenged folks know what you found. ;)

R1234

Will do Chuck! I posted over on the NCRS board to see if I get a nibble. This is what I get for bringing a car home in boxes. :crazy:

GDaina

All it is is a black wire, a light, you push the button, turns off the little light. Just like your wall switch. I had the thing appart a year ago, but can't visualize it.

JmpnJckFlsh

OK, 68rdstr, I have found one reference to the seat belt reminder light operation in the 70 Chassis Service Manual under "Electrical-Body and Chassis, Corvette Instruments and Gauges":

"Seat Belt and Door Ajar Indicators

Seat belt indicator is a thermal switch with a push reset. The switch is powered from the fuel gauge terminal. The switch is replaced as a unit."

"Black is ground" is not always a hard fast rule. I would expect the switch would be grounded by contact with the gauge cluster anyway. There appears to be a dedicated cluster ground of two black wires bonded together, one from the heater control lamp, but I can't tell how they attach to the cluster.

Perhaps the short black jumper wire is a power wire from the fuel guage. Which terminal? I would say the pink wire terminal, because that is coming from your fuse block. The tan wire goes to the rear harness connector and then to the fuel meter in the tank.


[Modified by Chuck Sangerhausen, 3:13 AM 9/5/2001]

R1234

Hey Chuck when do you sleep? :sleep: Thanks for your all your effort! :smash: So, with the ignition switch on, power is supplied to the fuel gauge, which is energizing the seat belt push button's coil, via of the black wire jumper from the fuel guage, which is illuminating the the seat belt warning light. The circut is made complete by the switch being fasten to the dash cluster housing, which is grounded to a chassis ground from the wiring harness. Pushing the seat belt button interrupts current flow, which drops the coil out causing the seat belt warning light to go out. So my next question is.... What keeps the the seat belt warning light from coming back on after you release the push button? Isn't power still being supplied to the push button's coil from the fuel guage?
My push button switch circut board currently does not have a socket or bulb. It has a hole with two notches opposite each other. I suppose a bulb socket would be inserted in to the hole and twist locked into place? The socket would line up correctly ( in series ) with the printed circut that Easy Mike refered to. Where to get the correct socket to hold a bulb?
Sorry to be such a PITA, but I figure I might as well try to get all the info on this thing while I got it out on the work bench. Anybody got any pictures :D

Easy Mike

My '68 chassis service manual says "Seat belt indicator is a thermal switch with a push button reset. The switch is powered from the fuel gauge terminal. The switch is replaced as a unit."

JmpnJckFlsh

Well, 68rdstr, I felt so sorry for you after I saw the pathetic response you got over on the NCRS Tech Board, I knew I had to redouble my efforts and get you a REAL answer. :D But, I believe I am at the end of resources, not having an assembled car to look at or to photograph.

I am just guessing here, but since they call it a thermal switch, I believe that energizing the switch causes a bitmetallic element to close contacts that energize the reminder light circuit which has the push button in series. Once the reminder light circuit is energized, pushing the button de-energizes the light circuit, but the bimetallic element remains closed. Once the ignition is turned off, the bimetallic element cools and returns to its normally open condition.

This is similar to the same way a relay works, only it is the magnetic attraction from a coil causes the second circuit to be energized. The electrically endowed call that "latching in"; once the second circuit is energized, power to the first circuit can be removed.

R1234

Thank you Chuck, Mike and GDaina. I guess the seat belt switch assembly I have is incomplete without the socket and light bulb. As Mike said it's sold as a unit.
Bryan