don't know, was on it when i bought it. about 9000 miles, 2 1/2 years
Well you may want to pull out the battery and load test it. On a '97 your probably a single phase charging system so don't expect much at idle. I therefore would suspect a weak battery/ poor battery cable connections or poor battery ground..
Once you know your battery is Good, strap a voltmeter across the battery and measure the voltage at idle and at 2500 RPM. Don't believe what you read on the meter until you know the battery is AOK.