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[Welung666]

The problem as I see it, is that the supply wiring to the power sounder is not adequately protected against a fault. The wires to the power sounder are tiny (no problem there. It takes about a quarter of an amp, and the wires are probably safe up to a few amps).

The problem is, this puny wiring is protected only by an 80 amp fusible link in the positive distribution box, and nothing on earlier cars without the box.

I suspect this is why the dash tends to go up too. Wiring is damaged through the loom until it reaches an adequately rated feed, probably by the fuse box.

Why, oh why didn't GM follow the fundamental rule of electrical safety and fuse the wire appropriately at the point where it is fed?

Would it be an idea to fit an inline fuse holder near the powersounder to act as an early blow device?

[Kevin Wood]

Would it be an idea to fit an inline fuse holder near the powersounder to act as an early blow device?

That would certainly help.

Kevin

[Debs.]

      That's bad news. 
SWMBO has just said I should get rid of my power sounder!

Mine`s already gone.

Seeing what damage (and danger) they cause I`m amazed there isn`t a thermal fuse built into the charging circuit: after all, the 12V. source can supply (briefly) limitless current.

[Kevin Wood]

Mine`s already gone.

Seeing what damage (and danger) they cause I`m amazed there isn`t a thermal fuse built into the charging circuit: after all, the 12V. source can supply (briefly) limitless current.

No sign of any protection inside the power sounder at all.

There is a piezo sounder driven via a transformer inside. A theory I have based on partial failure of my sounder is that leaking battery acid causes the drive to the transformer to go leaky resulting in DC current through the transformer and it or the wiring feeding it gets hot.

Eventually I guess it gets hot enough to start a chain reaction resulting in combustion and probably melting and shorting together of the supply wires to the sounder. Brake fluid reservoir is not far away and once the brake fluid goes up there is a lot of heat.

Not sure how it gets into the interior. I guess either burning brake fluid getting into the interior or that the wiring to the power sounder originates here and it overheats over its' entire length.

I guess they didn't want to fuse the feed to the power sounder for fear that it would be easily disabled but if you aren't going to fuse a circuit then you need to size it to handle any likely fault current.

Kevin