You guys are brilliant or I'm a dolt...or both. I have an Alpine SEC-8447 key fob. The stock radio has a flashing light likely for the alarm and there's a mystery small momentary toggle switch in the cubby box. One more thing to fix or remove altogether...

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'88 300TE, 175k, black RENNTech 3.6L Recaro C's AMG 1 SOLD
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'94 E320 Cabriolet, 110k, black, stock, SOLD
'88 300TE, 229k, dark grey, SOLD
'90 300CE, 212k, white, new paint, SOLD
'91 300E, 209k, white, rebuilt head SOLD
'74 914-6, grey, 2.7L 325hp twin turbo Audi conversion