1980s Seat Belt Chime - 1980 DeVille

[Eric DeVirgilis CLC# 8621]

The seat belt warning chime had been intermittently worked on a 1980 Coupe deVille I just purchased but now it has stopped completely. It's the mechanical bell type that sounds for several seconds after the ignition switch is first turned on. However, the "Fasten Seat Belts" dash indicator lamp illuminates/extinguishes with each ignition cycle as it would normally except not with the accompanying chime.

Looking for thoughts and ideas from anyone familiar with the chime unit. Does anyone have experience with these including whether it's repairable and know where it's located in the dash? If a replacement unit is needed, any leads on where to find one would be appreciated.

[TJ Hopland]

The 80 electrical manual under 'indicator works but chimes don't sound':
-check that seatbelt switch ground is clean and tight.
-check continuity through seatbelt with seatbelt unbuckled
-check seatbelt timer

seatbelt switch is part of drivers seat assembly

seatbelt switch ground is LH side of transmission hump under drivers seat

seatbelt timer-buzzer under LH side of instrument panel at accessory relay panel.

seatbelt chimes behind center of instrument panel near radio


Its all fet from GA-TRANS fuse 20 amp and then hits the timer module that has a note that says opens in 4 to 8 seconds.  Module looks to have 3 pins, the incoming power pink/black.  There is a ground pin black wire.  The output is a yellow wire that splits to the light and to the chime unit.  The light has its own ground.  The chime unit gets grounded by the seatbelt switch that says its open with the seatbelt buckled.  Also of note is there are 4 connectors between the chime module and switch. 

So if the light works I assume that means we have a good fuse and timer module and that its either a bad chime or seatbelt switch or the ground or any of those connections.

The manual doesn't go into any details about the module or chime unit.  The timer is drawn out to look like a little thermal heater deal kinda like a turn signal flasher.  The chime is just drawn like its a coil. 

The chime module looks like it just needs 12v and ground so that should be easy to test.  Yel+ and black white wire is ground.  C103 is what that connection is labeled.  I don't see that number anywere else in that system so that could just be a 2 pin connector that the chime module plugs into.

[Eric DeVirgilis CLC# 8621]

Thank you. I had forgotten the seat belt chime doesn't sound off when the driver's seat belt is fastened so that makes sense. Of course the chime unit itself can also be defective so will have to first verify whether it's getting power.

[smokuspollutus]

Usually the little foam rubber insulator at the bottom of the plungers travel turns to mush and binds up the plunger.

When the bell did sound, did it have a loud knock after each tone strike?

Fortunately they are usually easily repaired with a new piece of foam. I have seen one where the plunger must have been stuck so long that it did burn up the coil and was not repairable. This was on a newer car that had a multi function chime instead of the buzzer/chime combo that an '80 has. Same basic part but it was definitely more of a busy in that car.

[TJ Hopland]

The manual lists the timer-buzzer and chime as separate units and separate locations.  Oddly the only place buzz is mentioned I think is in the location chart so it could be something that was missed translating year to year or between models.  The way its drawn doesn't look like there would be anything in it that could buzz.

[smokuspollutus]

Yes, the buzzer and chime are separate units. I believe the chime is in the left center of the dash as I recall. Near the ashtray.

[Eric DeVirgilis CLC# 8621]

When the bell did sound, did it have a loud knock after each tone strike?

I'm not certain but I've always heard a soft 'thunk' sound between the chime bell on other cars.
 

 

[Eric DeVirgilis CLC# 8621]

Chime module is definitely faulty.

Power is present at lead for 5 to 6 seconds after ignition switch is turned on.

[TJ Hopland]

Where was it?   Not too bad to get to?  Or did you have to round up someone that weights about 50 ponds and has skinny arms that still bend backwards?

Its just a black box that plugs into a 2 wire connector hanging out of a harness?

[Eric DeVirgilis CLC# 8621]

To the left left of the radio. Wasn't as difficult to remove as I expected.

[James Landi]

More than a decade ago, I discovered that debris fouling foam rubber in my chime..()likely no longer under new car warranty.  And while you're at it, the electro/mechanical idle advance (on your throttle body injection system) needs new gear grease as the original grease degrades and turns in to abrasive that destroys the small plastic gears rendering them useless, and depending on where the throttle plunger gets stuck, you'll experience some high to very high revs .  James

[Eric DeVirgilis CLC# 8621]

More than a decade ago, I discovered that debris fouling foam rubber in my chime..()likely no longer under new car warranty.  And while you're at it, the electro/mechanical idle advance (on your throttle body injection system) needs new gear grease as the original grease degrades and turns in to abrasive that destroys the small plastic gears rendering them useless, and depending on where the throttle plunger gets stuck, you'll experience some high to very high revs .  James

Thankfully not an issue on an '80 RWD with 6.0 liter which is the last carbureted Cadillac engine. 

[TJ Hopland]

80 was the debut of the C-4 "Computer Controlled Catalytic Converter" which instead of running TBI injectors it ran an extra metering rod in the primary section of the Quadrajet that cold 'trim' the mixture by about +/- 10%.

Looking at the electronic manual it seems like they were just experimenting with the system at this point because it doesn't appear that the main computer is controlling the timing, that has its own sensors and control module.  It also dosn't seem to be doing things like the EGR.  It also doesn't show the idle control servo which seems odd so that must still be mechanical off the choke and or a simple solenoid off the AC.

81 I'm pretty sure they brought it all together where the one computer did it all and 81 was when all the other GM's got it too.  I never really looked at the 80's before so I didn't know that that system was just kinda half control.  I knew that the other 80 GMs had some extra electronics like timing so I don't know if they were just testing or doing the minimum to just meet emissions.

[Eric DeVirgilis CLC# 8621]

According to the owner's manual, only CA cars (w/6.0 carb engine) were equipped with C-4 system which also have Check Engine light.

[TJ Hopland]

So you are sure yours doesn't have any computer at all?  Does it have a vacuum advance?  I should go look for my 80 service manual and see what it says. 

80 seems to have been a pretty messy year with part year changes.  I have one listing with only 5 engine vin numbers.  For the 368 there are only 2, the 9 which is DEFI so Eldo, Seville but if I follow the footnotes and look at other specs it does appear to list the E4ME and the M4ME as carb options, the E being the computer one.  I was thinking they had a different vin for the CA engines but I guess that's only when the engine wasn't used on any of the 49 state models. 

Interesting the mid year V6 option does not seem to have an electronic option so I wonder if that just happened to pass CA emissions without special equipment that part year or if it wasn't available in CA or if the mid year option effects things like that.  You kinda would have thought mid year they would have just made those fully electronic but I suppose it wasn't just a Cadillac engine, it was going into a lot of Buicks and a few other GM's at the time so its not like they made them just for part year option of Cadillac's.  I think I read that the V6 80 cars did get the overdrive transmission so maybe that helped it squeak by the emissions? 

[Eric DeVirgilis CLC# 8621]

To my knowledge, no '80 with 6.0 carburetor has a computerized emissions system or a computer at all. Only CA cars.

The five engines used in 1980 are

6.0 carb (RWD std engine)
6.0 DEFI (Eldo std, credit opt Sev 49 state)
5.7 EFI (CA Eldo std, credit opt CA Sev)
5.7 Diesel (std Seville, opt all)*
4.1 V6 (credit option - all)*

* Exc Limousine