I have not dug into the dash lights for a while, but some things I would check are the Watt ratings of the bulbs you took out. Are they significantly different than the ones you are putting in (1.5 Watts each)? Also, check to see if the bulbs you bought have a built-in resistor. Most LEDs work at 2-4 Volts, and the bulbs have to have a means to drop the voltage from 13.8 or so to under 4 Volts. The manufacturer suggests it is rated for 13.8 Volts, and the kind that have an integrated resistor should work directly. Seems odd though that you blow the fuse if the lamp is not defective.

There may be another issue, that the current rise with an LED is much faster than the incandescent bulb and the fuse may be blowing based on current rise (they turn on faster). You might try turning down the dimmer a bit to add some conventional drop to the system to slow it all down.

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)