Electrical Problems

[k.smith904]

First off:


87 4.0L I6, AX-15, 2dr

Something is draining my battery to the point where I get a jump and can only keep it running for about a minute before it dies. Is this a short?

Where should I start looking for problems?

 

[Bstd_02_Wgn]

This could be something simple or you could be chasing gremlins. The info provide wont help much either.

Start by taking the battery to a place like Napa or Autozone, someone who can do a battery load test. This will determine if the battery is good or not. Something checking with a voltmeter across the terminals will display proper voltage, but when a load is applied the battery doesnt respond.

If the battery passes the test, start checking your grounds to the chasis and engine. If a ground is lose, weird things can happen. Also, take your voltmeter and place it across the battery terminals. Start pulling fuses one by one until the voltmeter reading stops deminishing. This will indicate which circuit your problem is coming from.

Start with your battery test, and see what happens. Most of the time this is the case.

 

[winterbeater]

You need to figure out if the battery and charging system is adequate before we can analyze the vehicle. Often it will be bad connections.

1. First thing is to take apart, clean, and reassemble battery connections and grounds, especially the ones from the battery to the body and the body to the engine. Clean them with scotchbrite or sandpaper, then electrical contact cleaner or mineral spirits.
2. The next step is to get a good charge on the battery with a battery charger. Might be a good time to take the battery in and get it load tested.
3. Check battery with a voltmeter with engine not running. Handheld is best, but the one on the dash works too. It should check 12-12.5 volts.
4. Start car up and check voltage. It should be 13-13.5 volts.

Don't expect it to run smoothly after a low voltage condition until computer get it's signals straightened out and relearns.

 

[k.smith904]

Thanks for advice.

For the record, I got the battery and alternator tested and both came out fine.

 

[joe_peters]

Ok, now you need to locate the draw that is draining your system.

With your battery fully charged you need to disconnect the neg and then the pos cables.

connect a 12 volt test light between the pos terminal and pos cable. Then connect the neg cable to the neg terminal.

If there is a substantial drain, i.e., something drawing enough current to drain your battery, the light will be quite bright. Let us assume that it is. Now start pulling fuses until the light goes out or dims. When it does, that is the bad circuit.

Some cars have a small draw at all times, i.e., radio's memory, etc. Those draws are low and the light will be very dim.

Once you have identified the problematic circuit you can unplug items on the circuit until you kill the light--and there you are.

 

[Mbjeep91]

The best way to check for a parasitic draw is to get yourself a cheap multimeter (one you don't care about burning up is something was to go wrong)
It has to have a fused 10amp DC setting. connect the leads to the proper slots on the meter for checking amperage.
Disconnect the negative battery cable
Place one of the meter leads to the neg post and the other to the cable.
DO NOT put one lead on pos and one on neg when meter is set for amperage, this will result in a dead short and cause the fuse in the meter to blow!
The reading should be .06 amps or less.
If it is more than this you have a draw on the battery.
From there you need to pull fuses until the draw goes away that will narrow it down to whatever is on that fuse.

Hope this helps.