i have a 83 300dt. the dash and instrument lights keep going out and the fuse #4 (as far as i recall) keeps blowing. the lights for windows and climate control also die with the dash. when i got the car, the rheostat was toast due to the oil pressure gauge leaking (not where the oil line gets screwed in, that is tight and clean...this is in the instument panel itself. the original rheostat was covered in oil and the spring was wrecked, so i jumped it with a wire after cleaning it and the lights worked for about 3 months. today i took the instument cluster apart and cleaned all the oil out of it and changed the fuse. after about 20ft out of the driveway, the fuse blew again...no interior dash lights including the speedometer.
my seatbelt buzzer was working intermittenly, so i replaced the relay today thinking this might be part of the problem...but no.
tomorrow i am gonna look again at all the other electronics connected to that fuse, but in the mean time, i was wondering if anyone else has had these issues and also, if anyone knows what to do about that leaking oil pressure gauge until i find a replacement at the pick and pull. can i use one from a different year/make? what are the opinions of just capping the line or rerouting it to a after market gauge? i don't care about a bit of oil on my pants, but my girlfriend would.
please help.

It's possible to temporarily substitute an oil pressure gauge from an auto parts store until you get a new cluster from a wrecking yard. You could also seal off the line but that would leave you with no gauge. Up to you.

Rheostat problems are common. many threads here on that subject. Make sure that all the bulbs are of the correct wattage and that the connections are not causing a short-circuit somewhere.

Jeremy

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"Buster" in the '95

Our all-Diesel family
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Aftermarket radio? Plugging something into the cigarette lighter?

Fuse 4 should be the radio and lighter, fuse 1 the dash lights. They interact at the radio. Check this thread.

http://www.peachparts.com/shopforum/showthread.php?t=154476

thanks for that link to the info about the radio and cigar lighter being connected. the electrical plug to the lighter was falling off and after connecting it up and putting in a new rheostat, i now have the brightest lights i have ever seen in this car. thanks so much for the help.

If you're using the old standard steel fuses, try the newer copper ones, and replace ALL of your fuses. The old ones pit, and build up resistance, causing other electrical problems, even though the fuses look fine.

The copper ones don't pit.

You can replace all of your fuses for maybe $8.