Help me solve this electrical mystery
sharrisgov
08-31-2004, 09:15 AM
I have a 94 Jeep Wrangler. Last summer, I replaced the battery, and the car ran fine until about February. One day, it just wouldn't start. Battery indicator was flat. This was after having not driven the car for about a week.
I jumped the Jeep, took it to the mechanic, and he replaced the alternator. Worked fine for a month, then, same problem--again after not driving for about a week.
Took it back to the mechanic, he replaced the battery and put on new cables. All was fine...until today. It's August now, and today, the Jee[ won't start. And yes, of course, it has been sitting undriven for about a week. This time, the battery meter shows a very low charge, but not zero.
What could be happening? Clearly, the battery is slowly losing its charge, but the alternator, the cable, and the battery are all new. If I drive the Jeep every few days, I don't have this problem. If it sits unstarted for a lengthy period, it dies.
I jumped the Jeep, took it to the mechanic, and he replaced the alternator. Worked fine for a month, then, same problem--again after not driving for about a week.
Took it back to the mechanic, he replaced the battery and put on new cables. All was fine...until today. It's August now, and today, the Jee[ won't start. And yes, of course, it has been sitting undriven for about a week. This time, the battery meter shows a very low charge, but not zero.
What could be happening? Clearly, the battery is slowly losing its charge, but the alternator, the cable, and the battery are all new. If I drive the Jeep every few days, I don't have this problem. If it sits unstarted for a lengthy period, it dies.
JDPascal
08-31-2004, 04:48 PM
Your jeep must have an accessory that does not turn off when the key is off or a short circuit that slowly drains the battery.
Check the glove box and consul lites first. If they are ok some electrical gauges are going to be needed.
The easiest is with an amp clamp that will allow a digital volt meter to detect the amount of current draining from the battery. If there is no amp clamp available, disconnect the negative battery cable from the post and connect the red lead to the cable and the black lead to the post. Use the highest amp setting and connection the meter has.
If the draw is less than 1 amp, switch to the lower scale and note the draw.
Once you know what the actual current draw from the battery is, you can start pulling one fuse at a time to isolate the circuit causing the draw. Once you have the circuit, use the wiring diagram to trace the loads on that circuit and fix it.
The normal key off draw should be less than 100 milli amps (0.100 amps) and some say 75 milli amps (0.075 amps)
If your alternator wasn't new, I would have thought that it could be the problem - not that it couldn't be stiill but it is unlikely.
Some jeeps had computers that get so they won't turn off when they should after the key is turned off
JD
Check the glove box and consul lites first. If they are ok some electrical gauges are going to be needed.
The easiest is with an amp clamp that will allow a digital volt meter to detect the amount of current draining from the battery. If there is no amp clamp available, disconnect the negative battery cable from the post and connect the red lead to the cable and the black lead to the post. Use the highest amp setting and connection the meter has.
If the draw is less than 1 amp, switch to the lower scale and note the draw.
Once you know what the actual current draw from the battery is, you can start pulling one fuse at a time to isolate the circuit causing the draw. Once you have the circuit, use the wiring diagram to trace the loads on that circuit and fix it.
The normal key off draw should be less than 100 milli amps (0.100 amps) and some say 75 milli amps (0.075 amps)
If your alternator wasn't new, I would have thought that it could be the problem - not that it couldn't be stiill but it is unlikely.
Some jeeps had computers that get so they won't turn off when they should after the key is turned off
JD
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