Under dash short
"Some things" to find the short
First, read the MAD article. Even if you end up "keeping" the ammeter, the diagram on their page gives a VERY good simplified view of primary power distribution:
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
NOTICE that there are a few things (depending on year) that ARE NOT fused
Power to the headlight switch is not fused, although it has an internal breaker. However, it "might" be possible for the light switch to develop an internal short to ground.....to it's case
Likewise the power going TO the ignition switch is not fused, and also, the power FROM the switch to ignition, start, and bypass are not fused AT ALL
The alternator charging wire to the alternator (black) is not fused. THE ALTERNATOR could develop a short to ground
HOW TO FIND
All you guys should have the following:
Service manual and "your favorite" wiring diagram, a multimeter, 12V test lamp, spark tester, and "clip leads" (alligator clip wires)
In addition, a HEAVY 12V test lamp is sometimes useful. I've used an old headlight with one working filament, and like to use a stop / tail lamp socket. You can wire the two filaments together or separate to create a higher / lower wattage draw.
SO...........
Remove the battery ground. Take your "heavy" test lamp and wire from ground to the battery NEG terminal. Make sure EVERYTHING in the car is off.....dome and trunk lamps, key, everything.
It lights? No? Check the fuse link, it must be hooked up. Turn on the headlights if the lamp does NOT light, and turning them on should cause the lamp to light.
If the test lamp is NOT lit, you have no short, the fuse link is blown or the connection open
Once you have all that "working" if that's the word, the NEXT step is to actually try to eliminate the short.
FIRST thing I would do is to pull loose the alternator main charging wire. If that does not solve the problem, wiggle the ammeter connections, and disconnect them. Pull the two ammeter wires clear off the ammeter and hook them back together. If the short stays "away" you likely have a short right there "in" the ammeter
You can try pulling fuses, but if the fuse link blows, they likely are not the problem
"Some things" to find the short
First, read the MAD article. Even if you end up "keeping" the ammeter, the diagram on their page gives a VERY good simplified view of primary power distribution:
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
NOTICE that there are a few things (depending on year) that ARE NOT fused
Power to the headlight switch is not fused, although it has an internal breaker. However, it "might" be possible for the light switch to develop an internal short to ground.....to it's case
Likewise the power going TO the ignition switch is not fused, and also, the power FROM the switch to ignition, start, and bypass are not fused AT ALL
The alternator charging wire to the alternator (black) is not fused. THE ALTERNATOR could develop a short to ground
HOW TO FIND
All you guys should have the following:
Service manual and "your favorite" wiring diagram, a multimeter, 12V test lamp, spark tester, and "clip leads" (alligator clip wires)
In addition, a HEAVY 12V test lamp is sometimes useful. I've used an old headlight with one working filament, and like to use a stop / tail lamp socket. You can wire the two filaments together or separate to create a higher / lower wattage draw.
SO...........
Remove the battery ground. Take your "heavy" test lamp and wire from ground to the battery NEG terminal. Make sure EVERYTHING in the car is off.....dome and trunk lamps, key, everything.
It lights? No? Check the fuse link, it must be hooked up. Turn on the headlights if the lamp does NOT light, and turning them on should cause the lamp to light.
If the test lamp is NOT lit, you have no short, the fuse link is blown or the connection open
Once you have all that "working" if that's the word, the NEXT step is to actually try to eliminate the short.
FIRST thing I would do is to pull loose the alternator main charging wire. If that does not solve the problem, wiggle the ammeter connections, and disconnect them. Pull the two ammeter wires clear off the ammeter and hook them back together. If the short stays "away" you likely have a short right there "in" the ammeter
You can try pulling fuses, but if the fuse link blows, they likely are not the problem