Congrats on your 92. I bought mine with 176 thousand in 2005 and I am going to roll over 200K in Febuary. There is a good community of 124 2.5s here. Not as big as the 123 and 126 but we are here. I have not seen this problem but I would bet on the switch as well. My mulit switch on my Grand Am has been screwing up for while.

If it is the switch and you can find the wires and isolate the switch. You should be able to test the resistance with a mulitmeter. If it goes to zero you have found the problem.

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My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory