91 Jeep Cherokee battery light problem!

jaspercomp · #1 (**permalink**) 03-22-2005, 04:53 AM

Hey all,

My 1991 Jeep Cherokee, 4.0 HO, is having an electrical gremlin. The battery light occasionally comes on while driving. The lights/wipers, etc...all run slower then suddenly everything brightens up and works correctly. Sometimes this does this without the battery/alternator light coming on. The battery is about 2 years old, and cables, ends, all are clean. I have read somewhere that if you constantly drive short distances, then that can be a killer for your battery. I drive about 3 miles to work and then home (night shift) Does this sound like a battery problem or an alternator? I'd hate to spend a lot of money on a alternator and it turns out to be a battery (and vice versa). Also, the check engine light recently came on about a month ago, goes on and off as well. But I'm not sure of a connection as the battery light thing has been going on for about 2 weeks. Thanks in advance for any assistance!

Joe
admin@jaspercomp.com

mujaman · #2 (**permalink**) 03-22-2005, 11:37 AM

if your check engine light is coming on... you should atleast start by having the codes checked. i'm not exactly sure how the setup is on a '91, but i think you should have some sort of a serial port for a scanner to plug into underneath your steering wheel somewhere (if its anything like my '97). take it to an advanced auto or autozone and have them check your codes (they'll do it for free).

mud4feet · #3 (**permalink**) 03-22-2005, 01:59 PM

While you're at advanced or autozone, they'll load check your battery for free also.

judge09 · #4 (**permalink**) 03-22-2005, 02:16 PM

It sounds like there might be a loose ground some where. Check your wiring.

Saurian · #5 (**permalink**) 03-22-2005, 02:28 PM

I would say ground fault as well, or a short... If it's just happening at random while you're driving, sounds like there is something either interrupting the electrical system, or taking a big load from it... Trace large wires, look for shorts, hanging things, loose ground screws/what have you...

I'm not too versed in the electrical nature of things, but these would be my suggestion, have worked on similar problems like this before.

XJNick · #6 (**permalink**) 03-24-2005, 11:28 PM

Hi,

I assume you are talking about the battery light on the instrument panel and NOT the check engine light? If so, the light is probably comming on when the 12-volt system is dropping below 9 or 10 volts (at which point you are damaging your battery by allowing the voltage to sag to low).

Being that you only drive short distances, your problem could very well be that the battery is never getting a full charge. You should measure the voltage at the battery both with and without the engine running. Without the engine running, you should see between 12.5 and 13 volts. With the engine running you should see between 14 and 15 volts. But seeing different numbers doesn't necessarily mean the battery is bad, as a loose connection in the charging system and/or a bad alternator could also be the cause of your problems....

-Nick