Im working on a 1990 Thunderbird SC Automatic. When I replace the fuse for the interior lamps(under the dash) it blows out right away. I tried adding a 30 amp fuse and everything worked again but fried the fuse box by the next day
I replaced the fuse box and Im stuck with the same issue again. Any advice on where to start is appreciated. Im a NOOB to electrical issues
-Fernando
Buy a copy of the EVTM for your car, either from eBay or from Helm Inc.
(EVTM - Electrical Vacuum Troubleshooting Manual, Ford # FPS-12116-90 on my copy of the 1990 one, from September 1989.)
But looking at my copy (Section 89), I would say the FIRST thing to check would be the wiring to the underhood lamp - I'd lay even odds, from the boneyards I've been in and from my history on my car, that the wiring has had the insulation fray and it's shorting out the 12V side. Or at least leaking to ground with considerable current.
You MAY spot where the insulation has gotten hot.
BTW - Do not, Do Not, DO NOT,
DO NOT UNDER ANY CIRCUMSTANCES do such a boneheaded stunt as swapping in an oversized fuse again, until you
KNOW why that fuse is blowing. Unless you just want to burn your car to the ground. That stunt is in the same shape as using a lit match to see how much fuel is in your gas tank by dropping down the fuel filler when it's almost empty. Think "Big BOOM!!!" ...
If you're troubleshooting, you CAN buy circuit breakers (think "Self-resetting fuses") that will plug in where the ATC fuses come out. I used one troubleshooting a short in my A/C compressor clutch line (well, didn't know that was where it was until I troubleshot it ... ) so I wouldn't have to keep buying that 15A fuse. Replaced the breaker with a fuse, and it's still good now that I've replaced the spot where the insulation had gone bad and it was shorting out.
RwP