Seat Belt Reminder 30884038 Wiring Help

frankrause · Post by **frankrause** » 02 May 2019, 11:12

Hello, I've been searching all over the place and I can't seem to find the following information. I'm looking for an explanation of the pins on a generic Volvo seat belt reminder, part #30884038

It has pins labeled 15l, 31D, 31, L, G and S

All the wiring diagrams I've found in Volvo manuals don't label the module with the above letters, even though it seems like it's a common module in several models. Anyone have any ideas how I might find the purposes of each of the pins? I think 15l is switched power and the 31D and 31 are grounds, but wouldn't G be a ground too? Thanks for any help!

Post by **RickHaleParker** » 02 May 2019, 21:02

look for pin numbers on the socket.

frankrause · Post by **frankrause** » 02 May 2019, 22:16

Ah, I don't have the socket. I'm using it in a project car and trying to update to some newer less annoying-sounding seatbelt chimes.

Post by **RickHaleParker** » 02 May 2019, 23:18

They look like DIN Standard 72 552 terminal markings but they don't quite decode.

frankrause · Post by **frankrause** » 03 May 2019, 13:20

Yeah, it's a bit of a mystery. Trying up pop this in my 1973 ES as a reversible mod to a less annoying buzzer. Here's what some fiddling has figured out:

15L - positive 12V
31 - 12V ground
3D - 12V ground

when 15L and either 31 or 31D are connected, G outputs +12V and S outputs -12V. The output is low-power, as it can light an LED test light but not an incandescent bulb.

I'm guessing that 31D and 30 are switched by the safety belts, so when they're disconnected a warning light or something at S and G is activated, but I can't figure out what L does - connecting it to G, S, +12V or -12V has no effect. I also can't figure out how to get the buzzer to sound, though it does crackle a tiny bit when I connect a 12V LED between G and S. A mystery!

Post by **RickHaleParker** » 03 May 2019, 16:13

frankrause · Post by **frankrause** » 03 May 2019, 20:33

Thanks for the diagram! It's strange that the terminals are labeled 31, 85 & 86 with the other three terminals unlabeled. Looks like I'll be doing a little more fiddling!

Post by **RickHaleParker** » 03 May 2019, 21:10

Did you notice two of the terminals, 4 & 6, are tied together internally? An Ohmmeter can identify these two.

With just the ground connected 86 will go high whenever +12v is applied to 85.

If you made it this far, there is only one terminal left to identify. Wonder which one it is.

frankrause · Post by **frankrause** » 04 May 2019, 13:22

Thanks, Rick!

Maybe mine is busted, there aren't any direct connections between any of the pins, but there's 1K of resistance between 15L and G.

When I connect 15L to +12V and 30 or 30D to -12V and then connect an LED between S and G I get a slight crackle from the buzzer - so maybe my module is busted, or maybe it needs to be connected to another module to fully function. Maybe I'll grab another next time I'm at the junkyard.

frankrause · Post by **frankrause** » 05 May 2019, 10:13

Got it!

I found a similar buzzer on eBay that was pictured with 31D labeled 86 and S labeled 85, it was a Rosetta Stone.

If I connect S to +12V and 31D & 31 to ground, the chime sounds.

15L - 4 - +12V constant
31D - 86 - 3 - ground switched by driver's door
31 - 2 - ground constant
S - 85 - 1 - +12V switched by key
L - driver's side seat belt latch?
G - seat belt reminder light, dome light, then ground?

I think! I haven't totally figured out L & G, I just wanted this for a chime noise when power is applied, since it's replacing a very harsh buzzer that is just a simple power connection. With this setup for some reason the light is on when the buzzer is not sounding and vice-versa, but like I said my setup only requires the chime function.