was driving my cherokee to work the other day and noticed the check engine light was on. but when i got back in the car after getting gas to continue on, the light was off. its been on and off for the past few days. i also noticed my battery gauge has been around 9, not 14 like it should be. when the light is on the battery gauge is around 9, but if i let it run and get to 14 light goes off. is this coincidence or could the battery really be the cause somehow?

 

Id say it's the alternator, not the battery. The light will come on if the system is under or over volted and if your gauge is at 9 volts with it running, your alternator is wonky

 

Get the code. There will be a "stored code" even if the check engine light currently isn't on. It will help you isolate this. How to do so is shown below; only takes a few minutes of your time.

I'd be sure to check serpentine belt TENSION as a loose belt can create a condition where the alternator isn't working properly; it's driven by the belt.

OBD1 Models: 1991-1995

1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost. Code 55 indicates end of fault code display.

 

1. Get the code. There will be a "stored code" even if the check engine light currently isn't on. It will help you isolate this. How to do so is shown below; only takes a few minutes of your time with a very simple key-on, key-off technique.

2. I'd be sure to check serpentine belt TENSION as a loose belt can create a condition where the alternator isn't working properly; it's driven by the belt. If belt is sufficiently tight, then the alternator is certainly in play as a primary suspect.

OBD1 Models: 1991-1995

1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost. Code 55 indicates end of fault code display.

 

I was getting a bunch of strange codes, (TPS bad etc) until I replaced my battery which was the original about 9 years old. No random codes since.