Chrysler Repair: 88 K-cars: Tail and dash lights fuse blows, light bulbs, dash lights

Question
"good morning. i am wondering if you can help me. my son's car is a 1988 dodge aries 2.5 litre. after buying the car we noticed that the dash lights and tail lights didn't work. my husband replaced the fuses. but this only works for a couple of days. then they go out again. fuses are changed again and the same thing happens. they only work for a couple of days. what do you think this may be? interior light works as do the headlights. your time and expertise would be greatly appreciated. the sooner the better as my son was already pulled over for having no tail lights but was only given a warning. the next time he will get a ticket. much appreciated. thankyou mich

Answer
Hi Mich,
I assume that it is fuse 5 that is blowing, if not let me now.
A fuse will blow when one of the wires that it supplies current to is shorted to ground rather than passing thru a light bulb. Unfortuately the fuse in question supplies about 20 different light bulbs and as many wires. Usually with the small light bulbs involved here the short is not the wire itself but more likely the bulb socket or the bulb itself.
Now to find where the short is there are two approaches: put a fuse in and turn the lights on. Then examine all the possible lights to see if one is either not on at all or is dim (a partial short to ground). Those would be the ones to remove and examine the bulb and its socket for possible rust or mechanical malfunction of the bulb contacts in the socket. It also could be the wires that are on the ends of the bulbs are bent so that one is crossed over and touching the wire that is next to it. So check the bulb ends for sign of such a short circuit. I hope that you will see an out/dim bulb as that would save you from going thru all the bulbs.
The other approach would be to split the job in half, using an ohmmeter to test whether the problem is the exterior bulbs or the interior bulbs, but that just cut the job in half. If you have a meter then you would go to the ignition switch and measure the resistance between pin I (tan wire) and ground, and do the same for pin R (black/yellow wire) and ground. Which ever reading is close to or equal to 0 ohms (short) is where to begin. Pin I is the interior bulbs, pin R is the exterior bulbs.
The possible bulbs are:
accesory lamp switch, air conditioning and heater switch, ash receiver lamp, instrument cluster lamps, radio lamp, gear selector lamp, console lamp, cigar lighter lamp.
licence lamp, parking lamps, tail lamps, rear side marker lamps.
I would be more suspicious of the external tail/parking lamps as those are the ones with the sort of wires on the bulb base that can easily short across and also are more subject to rusting/damage of the socket.
Let me know how this works out for you, please.
Roland
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