seat belt warning light/buzzer

mrmach1 · Dec 2, 2015

I know this may sound crazy but I want my seat belt warning light and buzzer to work if possible. Now here's the question do cars with a manual (4spd) trans come with this light? and if so where do the wires plug on the transmission/ shifter? MY car was originally a c6 automatic and it's been converted to a top loader 4speed.

timachone · Dec 2, 2015

I had them reworked too although it is a bit annoying sometimes... But I only had to replug one plug and insert a new buzzer which was bad.

From what I know the seat belt warning light comes with 4-speed-cars too because I have one

But on 4-speed-cars there is no conjunction to the transmission. The circuit consists of a switch in each of the front seat belt retractors, a switch under the seats, the bulb in the dsh and the buzzer above the glove box. These connections you have to check - often the plugs under the seats are unplugged...

jbojo · Dec 2, 2015

I had them reworked too although it is a bit annoying sometimes... But I only had to replug one plug and insert a new buzzer which was bad.

From what I know the seat belt warning light comes with 4-speed-cars too because I have one

But on 4-speed-cars there is no conjunction to the transmission. The circuit consists of a switch in each of the front seat belt retractors, a switch under the seats, the bulb in the dsh and the buzzer above the glove box. These connections you have to check - often the plugs under the seats are unplugged...

+!

It looks like they used a seatbelt timeout assembly. Not sure if it delayed the buzzer for a period of time before the buzzer went off if the belts were not used. No description on how it worked but it's in the electrical diagrams for 72.

mrmach1 · Dec 3, 2015

My car has no switch or connection of any kind under the drivers side seat. Under the passengers seat there is a plug for the seat belt warning buzzer/light. I have connections for the system in both seat belt retractors and I checked them both and of course the light and buzzer inside the dash on the passengers side. I seem to remember some sort of switch or connection that was on the the automatic trans that activated the system if you took the car out of park without connecting the seat belt on the drivers side, If someone sat on the passengers side seat the system would also be activated if they failed to pull the seat belt from the retractor wile sitting in the seat. I think that about covers it. If I've missed something let me know.

jbojo · Dec 3, 2015

Since there are no connections under the drivers seat I am assuming you don't have the auto seat back release. The drivers seat did not need seat pressure sensor so I would not expect any connections.

For 72 they used a timer that would energize the buzzer and light if the seat belt wasn't used in a predetermined time, similar to the cars today so they would not need a transmission switch. For 73 the timer is gone and they use the NSS switch to activate the buzzer if the car is taken out of park and the buzzer is immediate. Can't find any description of the 72 operation but looking at the schematics it appears to work the way I described. I tried looking for the timer switch but couldn't find one. You could probably find a suitable modern day replacement if you wanted this to work. Since it's all behind the dash you wouldn't know you were not using the OEM original timer.

mrmach1 · Dec 3, 2015

I did some research and found that there are two wires on the manual transmission that need to be connected to energize the system when put in gear. Now I need to do some searching on my car and find these.

Mister 4x4 · Dec 3, 2015

mrmach1 - I know what you mean about having the buzzer buzzing. When I was putting mine back together, I had just finished reinstalling the wiring harness and connected up the battery. When I opened the door and the key buzzer sounded with the dome lights coming on, I was ecstatic!! My friends in the shop were completely dismissive of my joy and annoyed by the buzzer, but they didn't realize how happy I was to have an actual working wiring harness. After having sat for at least 33 years, having even just the simple things like interior courtesy lights and key buzzer making noise when they're supposed to were just the first signs of my car coming back to life - which made me VERY happy. I still love hearing the buzzer - even though I'm sure it drives other people nuts.

I've also noticed that most folks who appreciate classic cars usually make comments like, "Wow - the buzzer even works!" ::thumb::

jbojo · Dec 3, 2015

I did some research and found that there are two wires on the manual transmission that need to be connected to energize the system when put in gear. Now I need to do some searching on my car and find these.

I am using the schematics for the 72 that are on this site and I don't see this switch. Can you tell me where it is in the diagram? I see a transmission switch but it appears to be part of the emissions system. I use these questions to teach myself how these cars are put together so it's a learning exercise for me.

thx

jeff8877 · Dec 3, 2015

John and Mrmach1,

Here are two pics of the seat belt warning switch for manual trans as well as connector 415 which plugs in on the trans. Hope this helps, this is from a 73 diagram.

mustang68 · Dec 3, 2015

I did some research and found that there are two wires on the manual transmission that need to be connected to energize the system when put in gear. Now I need to do some searching on my car and find these.

I`m the original owner of my 73 4 speed conv. You are correct, the BUZZER does not buzz in neutral ,(ONLY IN GEAR DOES IT BUSS) Their is seat sensor in both front seats. The sensor is under the seat, between the foam padding and the springs. When these cars were new, a lot people NEVER USED seat belts. So owners unplugged the sensors. My friend had a 72 mach 1 , 4 speed (he bought new) the sensors where in both of his seats,and worked the as same mine. You probably know this, their one wire on roller/ retractor, and when you pull the SEAT BELT out a little, The BUZZER stops buzzing I hope this helps you. I have all ways used my seat belt, So my sensors are still plugged in, and the BUZZER is still working like new.

jbojo · Dec 3, 2015

John and Mrmach1,

Here are two pics of the seat belt warning switch for manual trans as well as connector 415 which plugs in on the trans. Hope this helps, this is from a 73 diagram.

Thx Jeff,

I have a good set of 73 electrical schematics and you are correct that 73 has a switch on a manual transmission. For a 72 I don't see the transmission being a factor with the seatbelt warning system. I think that since this was a DOT requirement mid year(Dec) Ford may have just made it a timer function and further refined it for 73 to incorporate a transmission switch.

Someone with a working 72 system could confirm if the buzzer comes on automatically after a few minutes if the car is just started but not put in gear or if the buzzer comes on as soon as the car is placed in gear when the seatbelt is not used.

mrmach1 · Dec 4, 2015

Ok guys I think I'm getting the picture but here's the thing. When I bought my car it was an automatic and after an exhaustive search I found all the parts (some NOS and some just good used) to convert my car to a 4spd. The only thing I couldn't make work is the seat belt warning light and buzzer. The light worked flawlessly before and now thanks to all of your help I'm beginning to understand why I can't make it work now. I don't have any sensor on the drivers seat because the automatic system was different then the manual. I appreciate all of your help but I'm afraid this isn't going to happen at least not without another exhaustive search for more parts. Thanks again.

Mister 4x4 · Dec 4, 2015

I would think it's just a matter of tapping the right switched power source. One of my friends in high school had an early '70s Saab 99 with a manual transmission and seat belt sensors. They were always hot though, because I remember when I'd hop into his car for a ride to school, he told me to hold the button on the seat belt receiver so he could start the car. I remember being totally amazed that it knew I was in the seat and wouldn't let him start the car without the seat belts being used. Of course, it was a Saab - and they had different safety standards back then.

I don't know exactly how the circuit works in our cars, but I'm thinking you might tap a keyed power source so that if the car is on, the buzzer will sound if the seat is occupied and the belt not clicked into place to interrupt the circuit.

It's too bad manual transmission cars don't come with a Neutral light like a lot of the motorcycles - that would make things a lot easier.

jbojo · Dec 4, 2015

Just to add, the drivers seat will not have a seat pressure sensor because it is assumed that there will be someone sitting there unless you convert your ride to autonomous

mrmach1 · Dec 4, 2015

Just to add, the drivers seat will not have a seat pressure sensor because it is assumed that there will be someone sitting there unless you convert your ride to autonomous

Good point that is about the first thing I've been told that makes perfect sense. Thanks:thankyouyellow:

ok lets see what has to activate this system> I get in the car sitting in the drivers seat= no buzzer. I then turn the key and start the engine still no buzzer. Right? Then WITHOUT putting on my seat belt I put the car in gear. Light comes on WARNING and BUZZZZZ! loud and obnoxious. I quickly pull the belt from the retractor and the alarm shuts off. I don't even have to buckle the belt to silence it. So what activated the system? I think there was a connection on the natural safety switch on the automatic transmission but where does it get activated on my 4speed? Or am I totally off base here.

jbojo · Dec 4, 2015

For a 73 mustang there is a switch on the manual transmission that is used to detect the car is in gear. The auto uses the NSS switch and what you describe is the operation for that year. To sound the buzzer on the drivers side the car in gear closes one switch, the belt retractor switch is normally closed and connected to ground and will sound the buzzer if you don't have the seatbelt on. As soon as you pull on the belt the switch in the retractor opens and removes the ground and the buzzer stops. That's why you don't have to actually buckle the seatbelt. The two switches are in series so if one is open the buzzer will not sound. On the passenger side there is a seat pressure switch that detects someone sitting there and is normally open until a person is there. So 3 switches which are also in series have to be made for the buzzer to sound.

Now for a 72. The seatbelt warning system was not required until Dec of 71 so some of those cars may not have this. The electrical schematics show a seatbelt timer assy (108924) on pg 3 of schematic and indicates on Dec 71 and fwd on production cars. I don't see a transmission switch coming into play here. It does use the seatbelt and passenger sensor switches as far as I can tell. The following is based on my interpretation from the schematics on how this work:

** As soon as you start the car a timer is activated.

** If you don't put on the belt the buzzer will sound when that timer expires until you put the seatbelt on.

** When you remove the ground, power to the buzzer is removed but timer is still activated so that you can't remove the seatbelt again.

So I do have a question for you. You had mentioned that the system worked when you had an auto tranny. Did it not buzz until you put it in gear? BTW that timer should be on the plate above your glove box. I could be missing a switch some where but I don't have the actual schematic for a 72 like I have for my car.

mustang68 · Dec 4, 2015

Just to add, the drivers seat will not have a seat pressure sensor because it is assumed that there will be someone sitting there unless you convert your ride to autonomous

I order my 73 CONV. with351C 4V /4speed in1973. With that said it is 1 of 293 made. My car has seat pressure sensor in BOTH FRONT SEATS. My interior is still all original, and still looks like new. I hope this comment helps. My 73 LOOKS LIKE "NEW" just like my pictures in my profile. Larry

mrmach1 · Dec 4, 2015

For a 73 mustang there is a switch on the manual transmission that is used to detect the car is in gear. The auto uses the NSS switch and what you describe is the operation for that year. To sound the buzzer on the drivers side the car in gear closes one switch, the belt retractor switch is normally closed and connected to ground and will sound the buzzer if you don't have the seatbelt on. As soon as you pull on the belt the switch in the retractor opens and removes the ground and the buzzer stops. That's why you don't have to actually buckle the seatbelt. The two switches are in series so if one is open the buzzer will not sound. On the passenger side there is a seat pressure switch that detects someone sitting there and is normally open until a person is there. So 3 switches which are also in series have to be made for the buzzer to sound.

Now for a 72. The seatbelt warning system was not required until Dec of 71 so some of those cars may not have this. The electrical schematics show a seatbelt timer assy (108924) on pg 3 of schematic and indicates on Dec 71 and fwd on production cars. I don't see a transmission switch coming into play here. It does use the seatbelt and passenger sensor switches as far as I can tell. The following is based on my interpretation from the schematics on how this work:

** As soon as you start the car a timer is activated.

** If you don't put on the belt the buzzer will sound when that timer expires until you put the seatbelt on.

** When you remove the ground, power to the buzzer is removed but timer is still activated so that you can't remove the seatbelt again.

So I do have a question for you. You had mentioned that the system worked when you had an auto tranny. Did it not buzz until you put it in gear? BTW that timer should be on the plate above your glove box. I could be missing a switch some where but I don't have the actual schematic for a 72 like I have for my car.

It's been a long time since this system has worked but as I remember the buzzer would come on when the car was put in gear if the seat belt was not pulled from the retractor. I don't remember any such timer as the annoying buzzer would continue until the belt was pulled or the trans was put back in park.

This is starting to really bother me and now it's become a crusade of mine to figure this out and get this system working. I appreciate any and all help and ideas you friends have for me. I dug out my set original Ford shop manuals and I'm going through them in search of information.

Carolina_Mountain_Mustangs · Dec 5, 2015

Ok, I just got a 72 one owner convertible that is 3 speed manual so the system on it should be the same as a 4 speed.? I am moving the car to dry storage today so I will look under the seats and see what sensors are present. I will also see if the buzzer and light works, might not. Let you know tonight what I find.

David

seat belt warning light/buzzer

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