You really need to go at this with a multimeter, even a cheap one will work fine for what you need to do and help you narrow it down. First off would be to see what charge the alternator is putting out when running, second see if you have any AC voltage going to the battery with the car running, if anything seems weird then alternator is bad. The wires going to the alternator remain hot at all times so you need to trace those and make sure there is good continuity to them and if there is an internal short in the alternator that can for one cause the drain on the batter and two give you the problems your getting now.
The whole part with the alarm system is also weird. What you can do is with the car off and a good freshly charged battery in, turn off the alarm and have the doors unlocked. Pull the positive cable and set the meter to amperage and make a connection between the positive post and terminal using the multimiter. You should have very very little draw with everything off <.05 volts is typical. Then use the key fob to enable the alarm and lock the doors and then see if your amperage all of a sudden goes through the roof. If so then its an obvious problem with the factory alarm.
So when its losing power is everything shutting off like you blew a main fuse or something?
You should check your main larger fuses for any breaks that may be there, those square fuses are really hard to tell sometimes and sometimes even when they blow they will rest against each other making connection.
Another test you can do is when your doing the amperage test is if your getting a high amp reading disconnect one of the fusible links to the terminal see if it goes away, one supplies the battery voltage to the primary accesories and alternator charge and one for the ignition system and components. You can use that to isolate the problem, start there, then work your way down the harness and to different components.
But from what you said i can almost bet its an alternator issue, if its putting out an AC voltage (bad diodes) it can cause very very weird electrical issues, probably tripping the alarm system and or/ ecu causing the car to shut off.
Easiest thing to do is disconnect the postive going to the alternator and unplug the alternator and see if the issue goes away, on a good charged battery you should be able to start the car and so on without issues if the problem is taken care of on the alternator side of things. AC voltage on an electrical system is no good plus a bad diode could also be causing the drain to ground as well.
The whole part with the alarm system is also weird. What you can do is with the car off and a good freshly charged battery in, turn off the alarm and have the doors unlocked. Pull the positive cable and set the meter to amperage and make a connection between the positive post and terminal using the multimiter. You should have very very little draw with everything off <.05 volts is typical. Then use the key fob to enable the alarm and lock the doors and then see if your amperage all of a sudden goes through the roof. If so then its an obvious problem with the factory alarm.
So when its losing power is everything shutting off like you blew a main fuse or something?
You should check your main larger fuses for any breaks that may be there, those square fuses are really hard to tell sometimes and sometimes even when they blow they will rest against each other making connection.
Another test you can do is when your doing the amperage test is if your getting a high amp reading disconnect one of the fusible links to the terminal see if it goes away, one supplies the battery voltage to the primary accesories and alternator charge and one for the ignition system and components. You can use that to isolate the problem, start there, then work your way down the harness and to different components.
But from what you said i can almost bet its an alternator issue, if its putting out an AC voltage (bad diodes) it can cause very very weird electrical issues, probably tripping the alarm system and or/ ecu causing the car to shut off.
Easiest thing to do is disconnect the postive going to the alternator and unplug the alternator and see if the issue goes away, on a good charged battery you should be able to start the car and so on without issues if the problem is taken care of on the alternator side of things. AC voltage on an electrical system is no good plus a bad diode could also be causing the drain to ground as well.
Originally Posted by NI
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