Hello Ed,

I found the "dinger" on my '89. Up under the dash. Large and flat as "relays" go. About 1" x 3" x 4" or so. Blue. Has a slotted area on the housing which led me to suspect it was the dinger. Disconnecting it removed the ding sound. I stumbled across it while searching for the dome light delay relay. Easier to see from below than the dome relay is, but that's not saying much!

It's up somewhere around the pedal support bracket. I think to the right of the down-pointing heater vent. On the '90, it might be easier to go in via the instr. cluster; you'll have to be the judge of that.
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Sven: '89 245, IPD sways, electric rad. fan conversion, 28+ mpg - auto tranny. 850 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).