Our 93 Legend has 150,000 miles and has been doing pretty well until just recently. It has been off at college with our daughter. She developed what appeared to be a battery problem a few months ago, so we purchased a new Duralast battery. The problem actually seems to be an electrical drain which depletes the battery if the car is not driven in 2-3 days. She took it to a mechanic who was unable to find the drain, so I thought I would play with the car this weekend (we swapped cars this past weekend).

The first two things I did were to measure the battery charge, which was 11.48 volts before I left for work and 12.2 volts after I drove to work. I then changed my multimeter to ammeter setting and touched the probes to the + and - terminals. It showed a 0.2 amp current (my assumption is that there should be no current, just the voltage potential--is that correct?) So the question is how do I begin? My thought was to tediously remove the fuses one at a time to see if the current goes to zero, but my assumption is that the mechanic would have done that.

What circuits might be on all the time other than interior lights? (I will have to check the trunk light to see if there is a problem with the switch). Any thoughts?

Thanks
Ken K

 

ya that .2 amp reading was the amp reading through your meter your lucky it didnt blow the meter.

on a amp test you need to open a circuit and place then meter in the open and use it to reconect the circuit.

CAUTION most meters cant handle more than a 10 amp current flow.headlights will draw 20amps.

personally keep the meter on volts read the batt voltage and then start pulling fuses. if you unhook a power draw fuse your voltage will go up.

test this by turning on your lights then hook up the meter turn off the lights and see those volts start to climb.

btw knowing my acuras the way i do. hook up that metter and go unplug the alternator first.and unbolt its main power wire the 1 with a 10mm wrench (doing so with the battery hooked up can be tricky and may blow that 100 amp fuse so be careful.

 

OK, so what I should have done, then, was to have unhooked the ground strap from the battery negative terminal and bridged the gap with the ammeter. I realized that later.

So..."btw knowing my acuras the way i do. hook up that metter and go unplug
the alternator first.and unbolt its main power wire the 1 with a 10mm
wrench (doing so with the battery hooked up can be tricky and may blow
that 100 amp fuse so be careful."

1. How do I unplug the alternator?
2. I will check for the main power wire. Then, what I hear you saying, is that I should not have the battery hooked up (which it will not be, as I will have the ground strap unhooked). Is here any trick to unhooking the battery, or do I just undo the 10 mm bolt?
3. What is the reason for unhooking the alternator? I am happy to do it; I would just like to learn why I am doing what I am doing.
4. I will follow your advice about using the voltage meter instead of the ammeter.

Thanks.

 

hmm ya reading what i wrote i understand your confusion i think.

alternators have diode pack in them and when they short out they can draw power.

should be a round green plug on the back of the alternator with a clip on its side.push the clip and pull the plug.

do all this with the battery hooked up. and measure the voltage befor and after. i expect a gain in voltage showing a power drain.


if it passes that test then take a voltage reading, unhook the batt so we dont short the wiring.
then unbolt the alternator power wire. (it should be white in color)
then hook up the batt and retest for voltage.

if no change then back to square 1 and start pulling fuses.

OR drive to auto zone and see if they can do a free charging system test a bad diode can be seen as ripple in a DC circuit.

i hope this is a little bit better.



Edited by: acuralegend

 

Mo betta.

My weekend is cut out for me...

Thanks
Ken K

 

I went through the fuses (engine compartment and driver's side interior) using the voltmeter and did not find any problem. However, this AM my voltage had dropped from 12.04 to 8.96 over 36 hours. This time I went through the fuses again, but using the ammeter instead. I found a small drain related to an engine compartment fuse called:

Bose
H/L Washer

We don't have headlight washers, so I am wondering what other things this fuse controls? I don't have a manual. (Is there an online manual anywhere? I could not find one.

Thanks
Ken K