Joe C

anyone have a circuit schematic for the C4 chime or alarm, (seat belt, ignition key, head lights) module, PN 10037040?

pcolt94

No schematic.
I did fix my chime box. I did troubleshoot it and found nothing wrong electrically all signals were all there and working but no sound or chime. I found the two large supports on either side of the chime horn had bad connections. Did not look bad but re-soldered it with good heat (since the metal is heavy) and after that it worked.
This is the heaviest weight on the board and sure time and vibration caused cracks in solder.
I soldered the lands for the input for the horn also.

I could not figure why this fixed it. It was strange with doing electronics all my life. It just looked like a support. Did not make sense but you can't argue with success. Did it in 2004, still working fine.

Joe C

, and thanks....

belairbrian

Sounds like the supports were acting as part of the circuit, maybe ground for the buzzer.


Just curious, did you go into the dash just to fix the buzzer, or were you already in there for some other reason?


At least on my 92 it's a lot of work to get there. My works when it feels like it, but I can't see disassembling the dash to get at it.

pcolt94

It was probably within the first year of buying the car where I had a list of items to fix after I did a tune up and the general maintenance and fluids. I was into the dash for the PKE and had to remove the chime unit to get to the PKE. Thought I would give the chime unit a go at it since it was out already.

I agree it could have been a ground for the chime horn but it is driven like you would drive a speaker. I did not see how the ground should affect the operation of it. But I did not have a schematic or a specific knowledge of theory of operation. I was my last thought like what the heck it's a shot in the dark and was surprised when it worked 100% as it was intermittent.

Joe C

, more than likely, it's an electrical connection. nothing exotic on the circuit card - mostly standard components. there is a 16 pin DIP, but trying to ID the thing is problematic since it's buried under the sound module (which is nothing more than a speaker). the IC, most likely is a timing circuit and/or oscillator. as I said, nothing exotic - individual component failure, IMO, is pretty low. still would be nice to have a schematic for trouble shooting purposes - even a pinout would be helpful. I guess one could reverse engineer a schematic, but for me, i'm just not that ambitious.

WVZR-1

For the 10037040 with it's use in so many GM applications I doubt it would require much of an effort to gather a 'handful' for dissection. The 10037040 doesn't appear to be OE for an '85 so unless you actually have the 10037040 in your '85 you might be interested in looking further.

Also for Internet searches and maybe circuit information if you used 10037041 which is the 'inked' assembly ID on the case you could maybe do better. Anyone who disassembled one who was interested might reference it to that information.

If you've removed one from the case was their any information actually on the board? You might inquire some of that.

I was surprised that Cliff Harris didn't have one or Rob Healey maybe. I checked Cliff's 'mrpeachy' and didn't see anything. Maybe reach out directly to Cliff.

If you've removed from the case - how similar to this is yours?

https://forum.allaboutcircuits.com/t...-board.143710/

Joe C

correct, the actual part number in my 85 was 10037041. they look identical except for the PN inking. I have several 10037040, and just "assumed" my original was the 040 part. anyway, replaced my original with a NOS 040 part, and everything seems to be working as normal. I did internet searches for "schematic (both PN's) and came up with nothing. I've removed the circuit card from the case, and other than a few components ID's, no other identification. if there is a difference between the 040 and 041 parts, I doubt it's an operational difference. one note, the circuit does have a couple electrolytic caps, and those do have a limited life span. might try replacing those and follow pcolt94's advice and check solder connections. most likely it will go on the back burner since everything's back to normal with the NOS-040 part.

BTW, the module in your attached link looks nothing like my 041 part. 84's must have a different part number altogether - ??? finally, as far as an 85 goes, it looks like both 040 and 041 parts are alternate and interchangeable. seems the 041 part is called out for the 85-89 model years.

edit: now this is getting confusing - i'll have to verify this, but it looks like the 040 part has a 8-pin connector where as the 041 is a 7 pin connector. same basic layout, but an extra pin. I never notice the difference. it was still a direct plug in, so i'm guessing the 040 part has an extra circuit or feature. I have a second NOS 040 part, and i'll have to pull it for a "apples to apples" comparison.

in any event, NEW correct alarm modules for the 85-89 corvette, PN 10037041, are almost non-existent. it seems that the more common 040 module, used across various other GM lines is more readily available and can be purchased without the corvette tax. as far as I can tell, there's no operational difference. i'll dig deeper into the 040/041 difference and post back....

WVZR-1

Working - GOOD!!

So it appears your '85 had been replaced 'once' already before your purchase. An '85 I would have expected to have had a 14062570 if still original.

belairbrian

The picture does have some clues. It shows being made by Lectron. They were in Rochester Hills MI. From what I could find they were bought by Eaton in 94. So if the drawing exists it's probably in their archives somewhere. Doubt they would put much effort into finding it for anyone.

Joe C

if it was replaced, it was before I bought the car in 1995. the date code on the module i pulled was (Julian date) 5 177, or june 26th of 85. that would coincide with my july 85 build.

Joe C

- there are several lectron patent numbers on the case - that might be a clue.

more info - a google search on one of the pat.nos. yielded this - Driver circuit for tone generator - https://patents.google.com/patent/US4183278. information is somewhat vague, but none the less, still another piece to the puzzle.

pcolt94

94 car
I guess that is the earlier module as from what I remember mine looked totally different as far as the actual chime unit. Mine stood tall on the board like a cone tower (like upside down ice cream cone). Then on either side of the top were 2 supports (flat metal) that went down to the edge of the board at a 45* angle. Obviously different than what was being worked on and information for it. Memory from 10+ years ago.