Seat belt buzzer won't stop.

[Jughead]

Hi All,

('72 240Z)  My seat belt buzzer won't sop buzzing with ignition on and only the driver on board.   It does not buzz when in neutral. 

Where is the problem likely occurring? What should I check, and in what order?  Could the issue be under the passenger seat?

Thanks!

[SteveJ]

Probably, try to disconnect the sensor under the passenger seat.

[Jughead]

On 8/2/2020 at 10:30 AM, Jughead said:

Hi All,

('72 240Z)  My seat belt buzzer won't stop buzzing with ignition on and only the driver on board.   It does not buzz when in neutral. 

Where is the problem likely occurring? What should I check, and in what order?  Could the issue be under the passenger seat?

Thanks!

Update:  Ended up just disconnecting the buzzer.  It was easy. It's located under radio - driver's side.  Follow the buzzing sound under dash, then feel for it.  It vibrates. 

I then accessed via the fuse door.  I removed 2 screws from fuse box to move it out of way.  Once  done, you can pretty easily "pull the plug" on the buzzer (look for green and black wire) .  The red warning light still lights, but it's fine. 

Some day I'll figure out the root cause of the original problem and plug 'er back in.    Until then, no annoying buzzer!  

[Zed Head]

Isn't the connection made in the seat belt latch itself?  Latch it the buzzer turns off, open it the buzzer turns on.

[qz16]

I believe that the buzzer and the warning lamp should be extinguished if you close the door AND buckle the driver seat belt, assuming there is no passenger.

I do not believe that there is a neutral switch on manual transmissions.  Just curious - Is this an automatic transmission?

 

You do not have to reconnect the buzzer to diagnose the problem.  The seat belt warning lamp turning off will tell you when the circuit is corrected.

 

First thing that I would check would be both door switches – when the door is closed a plunger mechanically disconnects the lamp and the buzzer from ground.  You could just pull the single connection from the mechanical switch and that would be the equivalent of the switch working and the door being in the closed position.  The switch is on the door frame.  Just below the top hinge.  You can access the switch from inside the cockpit.  It may be covered by a masonite panel.   The connection is at the back of the door switch and it is usually a spade connector.  I would disconnect the switches one at a time to see if the buzzer AND the warning lamp are extinguished.  If the buzzer is still sounding and/or the warning lamp is still lit leave the door switches disconnected and move on to the belts.

 

Next would be the seat belts.  The seat belts normal condition connects the circuit.  If you extend the belt and cause the moveable belt side tang to be grounded it breaks the connection.  I would extend the driver’s belt and connect it to the other side of the driver’s seat or jumper the moveable side of the belt to ground.  Buzzer and lamp should be extinguished.  If the problem persists then I would suggest disconnecting the driver’s seat belt.  This connection is on the left side (out board side) of the drivers seat.

 

If you decide to debug the problem then please post the results so we can figure out a next step. Hope this helps.

Good luck

[w3wilkes]

5 hours ago, qz16 said:

I do not believe that there is a neutral switch on manual transmissions. 

Can't speak for sure on a 72, but on my 73 with a manual transmission there was a neutral switch. The buzzer would buzz when in gear, but not in neutral when the seatbelt wasn't buckled for either passenger or driver.

[qz16]

w3wilkes
Thanks.  I have a '73.  Can you help me locate it?  Where is the switch and the wires for it?  I see that there is a neutral switch on the wiring diagram, but never saw anything physical that i thought might be the actual switch.  Thanks in advance for your assistance.

regards,

ron

[w3wilkes]

Ron,

Sorry, I haven't had my 73 for 20 years and my early 71 is a pre buzzer car. The only switches I'm aware of are under the seats. You could try unplugging one of them and see if the buzzer quits, if not then try the other seat. I believe these are micro switches that complete the circuit to the buzzer when you put weight on the seat.

Good Luck,

Wilkes

[cgsheen1]

1 hour ago, qz16 said:

w3wilkes
Thanks.  I have a '73.  Can you help me locate it?  Where is the switch and the wires for it?  I see that there is a neutral switch on the wiring diagram, but never saw anything physical that i thought might be the actual switch.  Thanks in advance for your assistance.

regards,

ron

But do you have a 1973 4-speed transmission? Some of the Z transmissions have a neutral switch, some don't. The years that do have two sets of two-wire connectors down the firewall into the trans tunnel in the stock harness configuration. One for the reverse light, one for the neutral switch. The neutral switch screws into the side of the transmission just like the reverse light switch. I can't remember if they both have bullet connectors or if one has bullet and the other spade. Probably the latter - even back then Nissan was trying to make it easier "not to plug the wrong things together".

[qz16]

sheen,

Thanks.  You must be correct.  I have seen trans switches for z cars that have spade connectors.  These must be neutral switches.  you have far more experience with zcars than I.  I thought most manuals have a contact switch for the clutch, to prevent starting unless the clutch is depressed, but who knew that datsun would be so advanced back in 73.  I also read that not all 4 speeds had neutral switches, and as far as i know the 5 speeds did not.  As you know the bucket is a 73 with an L28 and a 5 speed so questions about stock are always interesting.

thanks,

ron

[w3wilkes]

So my 73 must have had the neutral switch since the buzzer would shut off going through neutral when the seatbelt wasn't fastened. As far as starting the car in gear goes, that was no problem on my 73. When my slave clutch cylinder broke I would just put it in 1st, start the car in gear and go. Then it's just a matter of gently shifting while the RPM's drop between gears. Put the car in neutral to stop at the light, shut off the motor, put it in 1st and start in gear when the light turned green.