Oil pressure sender, mine failed some time before.
Connect 12volts straight to horn up from the engine and check if horn itself is blown.
Try to open your blower motor housing and connect 12 volts directly to blower motor to see if it spins. If it does then it might be blower motor regulator.
Subscribe to alldata diy. diyalldata.com. I dont know what i would have done without it.
Good luck

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1999 ML430 Silver 135k ml
Smoked LED taillights, Alpine in-dash DVD player, 12" sub, Pioneer components, 2 amps, 4200k HIDs, ML55 headlights, 20" rims, mirror LED blinkers

SOLD. 1996 E320 145k ml. Burgundy

SOLD but miss it everyday 1992 500sel Black
Chime buzzer mod,Alpine CD/MP3 player with stock amp,Euro headlights,S600 grill,20" rims, BEST CAR EVER!

SOLD. 1990 300E White
187k ml,smoked tails,Euro headlights,17rims,Intake,12" sub in first aid kit,alarm/autostart,buzzer mod