seat belt warning light/buzzer

[mrmach1]

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

Thank you I really appreciate your help.


I have the same diagrams that everybody else does but not being a Electrical engineer I can't make head nor tail from it. The early mustang diagrams were much more simple and even the 71 diagram is understandable but in 72 they changed and go very confusing so they aren't much help.


The Diagram from Jbojo shows a "SEAT BELT WARNING SWITCH MANUAL TRANS. Where is that located on the car.

 

[jbojo]

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

Thank you I really appreciate your help.


I have the same diagrams that everybody else does but not being a Electrical engineer I can't make head nor tail from it. The early mustang diagrams were much more simple and even the 71 diagram is understandable but in 72 they changed and go very confusing so they aren't much help.


The Diagram from Jbojo shows a "SEAT BELT WARNING SWITCH MANUAL TRANS. Where is that located on the car.

Jeff posted that diagram but it's for a 73. I sent you a link where you can get a set of colorized diagrams for the 72.

 

[mrmach1]

Ok for all of you that are following this thread there appears to be on 72 manual trans cars 3 and 4 speed what is called a T.R.S (transmission range sensor) which is about the same thing as a neutral safety switch on automatic trans. I seem to remember that the seatbelt warning light was connected in someway to the NSS and the activated by shifting out of the park position if the seat belt was NOT pulled from the retractor. I'm still in the investigation stage of this project. I have a feeling I never connected this sensor at all in my car hence the reason my seatbelt light/buzzer is inoperable, but I'll figure this out yet.

 

[OMS]

From what I know / learned

Some 71 cars had a " belt minder system "

It was an option

The system used a timer to light the round red "belt" light on the lower LH drivers side dash.

When the car was started the light flashed until the timer timed out.

I don't remember if it buzzed too.

It was a complete stand alone plug and play unit.

Seems the higher optioned cars had them.

After Dec 71 all 72"s and 73"s had the buzzer and warning light in the passenger side dash.

Both seats had sensors and the system would light and buzz, when the car was taken out of park for automatics and put into gear on manual transmissions. It would continue until the seat belt was pulled out of the retractor.

We use to just connect the belt across the seat and sit on it.

You could also remove the sensor under the seat.

The manual trans cars had a switch in the trans - fairly hard to find as these were 72-3 only. I think the trans case had a D2 casting number

Don

 

[mrmach1]

From what I know / learned

Some 71 cars had a " belt minder system "

It was an option

The system used a timer to light the round red "belt" light on the lower LH drivers side dash.

When the car was started the light flashed until the timer timed out.

I don't remember if it buzzed too.

It was a complete stand alone plug and play unit.

Seems the higher optioned cars had them.

After Dec 71 all 72"s and 73"s had the buzzer and warning light in the passenger side dash.

Both seats had sensors and the system would light and buzz, when the car was taken out of park for automatics and put into gear on manual transmissions. It would continue until the seat belt was pulled out of the retractor.

We use to just connect the belt across the seat and sit on it.

You could also remove the sensor under the seat.

The manual trans cars had a switch in the trans - fairly hard to find as these were 72-3 only. I think the trans case had a D2 casting number

Don

Thanks Don and from what I've learned from both my own experience and from others here in the forum what you say is absolutely correct. I just ordered the colorized wiring diagram on disk. I think this will help me straighten out this and a couple other electrical issues I've been dealing with and could prove an invaluable asset moving forward. Thanks again.

 

[Carolina_Mountain_Mustangs]

We had communicated some on PM but thought I would post here also so all can read.

I took the 72 one owner vert to storage a couple days ago. When you get in the car and start the light comes on, buzzer is not working. When I fasten my belt the light goes out. If you put pressure on the passenger seat and put the car in gear the light comes back on. So there is some kind of connection to a switch on the shifter or transmission if a passenger is in the seat and you go in gear the light and buzzer are activated and stop when the belt is pulled.

David

 

[mrmach1]

Thanks David for reaffirming my memory of how this system works. I really appreciate all of your and others efforts in my behalf. This a great place to go for help with anything that has to do with these cars. Thanks again.

 

[mrmach1]

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::

It's funny how even the smallest of things can give us car nuts joy.

 

[mrmach1]

I still haven't figured out how to make this seat belt warning system work again. I would love to see pictures of the connections at the transmission and where the wires go from there. If anybody has a 4 speed and this light/buzzer on their car and wouldn't mind taking a couple pics and posting them I would truly appreciate it. Thanks in advance for any and all help.

 

[jbojo]

I found the location of the sensor switch on a 4 speed transmission. Attaching a pic diagram where it should go. Looks like it the mounting bracket goes between the 2 forward shift levers and the sensor is toward the top of the unit.

 

[jbojo]

The wiring should still be there if your car had the system and it was automatic. In the engine compartment on the drivers side firewall there should be a square 4 pin connector. I believe that the wires should be light green and the other pink white with white hash stripes. These are the two connectors for that transmission switch and was also used for the NSS switch for automatics. With the switch installed and the transmission in neutral the light and buzzer would be off.

 

[midlife]

The wiring should still be there if your car had the system and it was automatic. In the engine compartment on the drivers side firewall there should be a square 4 pin connector. I believe that the wires should be light green and the other pink white with white hash stripes. These are the two connectors for that transmission switch and was also used for the NSS switch for automatics. With the switch installed and the transmission in neutral the light and buzzer would be off.

True for after December, 1971. Before then, the wiring was a bit different.

 

[jbojo]

The wiring should still be there if your car had the system and it was automatic. In the engine compartment on the drivers side firewall there should be a square 4 pin connector. I believe that the wires should be light green and the other pink white with white hash stripes. These are the two connectors for that transmission switch and was also used for the NSS switch for automatics. With the switch installed and the transmission in neutral the light and buzzer would be off.

True for after December, 1971. Before then, the wiring was a bit different.

+1

Do you know if there is a electrical schematic that shows the alterations after Dec for the 72's . I saw that there was different wiring setup prior to Dec. I am thinking that it was the same as 73 models. The schematic that I have for my car has the transmission switches in them. In the 72 schematic I see a note at the end of a wire run that says after Dec but it just stops there.

 

[midlife]

An incomplete wiring schematic is in the 1972 vacuum and wiring diagram books that are 11x17". I say incomplete because one connector is showing for the earlier version (IIRC) but it doesn't show where its mate goes.

Sometimes I hate Ford...

 

[midlife]

I've been working with MrMach1 on this for some time now, and it does appear that there are two separate harnesses for post-December 71 mustangs w/manual transmissions. The backup harness attaches to the shifter mechanism, but the seat belt attaches to the transmission, much like the 73s. I've even identified the 1972 wiring harness from the MPC. What I don't know is what triggers the seat belt warning within the transmission.

Does anyone with a post-Dec 71 owners manual look within the manual and say when the seat belt reminder light should come on? My guess is that it comes on whenever the manual transmission is put into gear (R, 1, 2, 3. or 4th).

 

[mrmach1]

This is the switch I think goes to the seat belt warning light on a 72 with a manual transmission.

 

[jbojo]

I have found 2 references to the location of this switch. For a 3 speed it is towards the center of the trans body while on the 4 speed it's more towards the top. I haven't been able to find a picture of one removed yet but it appears to be a plunger type and rides on the shifter rods that are internal. I did see that these rods do have dimples in them for R, 1st, 2nd, 3rd and 4th so I am speculating that this switch makes contact when the plunger hits those dimples, just speculation as I can't find anything that describes its operation.

 

[mrmach1]

I'm now very sure that this is the switch but I've been unable to find the connector and wire harness needed to connect this to the rest of the harness in the engine compartment. I'm afraid I'll have to get creative nd make my own. Then comes the question what does it plug to to get power. I've been working with Randy( Midlife) trying to get this system back in operation but I'm still no closer to reaching my goal.

 

[jbojo]

Since your car had the seat belt items when you had the C6 the connector should already be in the driver side of the engine bay. This switch would is in series with the belt retractors and seat sensor and the necessary power connections should already be there and connected. The only unknown is the 4 spd that you have and whether it has the necessary fitting for the switch on the case that you have. Have you looked to see if it is there now? It would be possible though to make a switch external to the case that would work. Attaching a pic of a 73 tranny with the switch and wires on it.

EDIT: I added a very basic diagram irt how I believe the circuit would work. If there is a passenger seated without putting on the belt the buzzer would go off even if the driver has the belt on because the ground path is being supplied via the passenger ckt because the seat sensor is now closed.

 

[mrmach1]

Since your car had the seat belt items when you had the C6 the connector should already be in the driver side of the engine bay. This switch would is in series with the belt retractors and seat sensor and the necessary power connections should already be there and connected. The only unknown is the 4 spd that you have and whether it has the necessary fitting for the switch on the case that you have. Have you looked to see if it is there now? It would be possible though to make a switch external to the case that would work. Attaching a pic of a 73 tranny with the switch and wires on it.

EDIT: I added a very basic diagram irt how I believe the circuit would work. If there is a passenger seated without putting on the belt the buzzer would go off even if the driver has the belt on because the ground path is being supplied via the passenger ckt because the seat sensor is now closed.

The switch is there no question and it tested fine but I need the wiring and connector that goes to it and the rest will fall into place. The pic you enclosed shows exactly what I'm looking for. Do you have one? This is a pic I took of my transmission and the switch is visible on the right with two male prongs.