Electrical Short, Dead 4Runner

[TRunner]

So my runner is dead on the side of the freeway and I think it is something electrical. A little background on the rig:

Has a MR2 alternator, batteries haven't been lasting very long (3 batteries in like 1-2 yrs). When the battery is about 3-4 months old sometimes it won't start and you get the click like the battery is dead. If I keep the key turned sometimes it starts, sometimes when I let off the brake pedal it starts. PS headlight is extremely dim. Replaced the light and the new light is still dim. Never really was able to fix any of these problems.

Now for the recent problem:

Last week my radio turned off and then back on while driving. I then noticed that all of my gauges on the dash were out. Found a 15A fuse by the drivers left foot, and that got the dash gauges back up. A few days later the same thing happened again. I haven't replaced the fuse yet. This morning while driving to work the radio turned off and on several times in succession. I took off the face to turn it off. (I installed the radio about a yr and half ago, no problems until now). I also noticed that the truck didn't seem to have the power it usually does. About 5 miles on the freeway and it started losing power until I was on the side of teh road coasting and the motor stopped. I was close to the end of my tank of gas so I thought (hoped) that was it. Put in 5 gallons and the thing wont start. Gives the dead battery sypmtom. I'm wondering what the cause could be. Perhaps a short somewhere that is draining the battery and somehow was also blowing the fuse, but remember that particular fuse is blown and the radio was still turning off and on. Any thoughts??? :help:

UPDATE: the battery is completely dead (hazard lights were left on)

[Oatmeal]

Sometimes the problem is ridiculously simple. Mine had almost the exact symptoms (the radio off and on thing), turned out the factory positive lead at the battery was corroded through (under the insulation so, you couldn't really see it!) check there........maybe you'll get lucky!------Hans

[fourwd1]

Yes, first check all the battery cable connections, pos and neg. Make sure they are clean and tight.

Then check the alts output voltage while running, should be at least 13.8V. Use a DMM, don't rely on a dash gauge, they're not real accurate.

If it's too low the batt won't charge properly, and if it's too high you can overcharge the batt, and it won't last long.

With a good (charged) batt, put the DMM in DC AMPS mode and connect in series with the pos cable. Have the engine and everything OFF and measure the current drain. If it's greater than 50 mA (.050 A) it's too high, and could be the cause of your problems.

[TRunner]

Thanks for the posts. It turns out that the fuse that was blowing (the one that wason the dash guages and blinker circuit) also is tied into the alternator. It is some control circuit. So when I didn't replace that fuse the alternator basically wasn't turning on. I haven't found "the" culprit for that fuse blowing, but I did clean up some wiring that needed to be cleaned up. and it hasn't blown since.

WARNING: if your 15A "engine" fuse in the drivers kick panel blows and your dash goes dead replace it!