There is more of a load on the engine when these accessories are turned on and more of a load on the belt. If the belt is slipping and making noise the voltage will drop. I would change the belt and tensioner as the tensioner is not keeping enough tension on the belt to stop it from slipping and making noise.
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Hello, thank you for your response. The belt is new, and this model jeep does not have an adjustable tensioner. The belt is adjusted correctly, and all the pulleys have been checked. This problem pops up on the jeep forums alot, but never seems to be solved. I have been driving Cherokees for my entire driving career (over 1,000,000 miles) and I have owned an '88, '89, '94, and now this '99. I have never had this issue before.
Some other info to digest: Before I replaced the alternator and battery, the voltage would be low when the car was started (12 or so) and stay that way until a clutch or something kicked in after idling for a couple minutes. (engine sound would change, but RPMs would actually go down...it sounded like a fan came on) Then voltage would climb to 14...until the morning it dropped to 0 and the belt started to smoke, which i when I replaced the alternator, belt and battery.
hello i'm bill
i have seen this many times the belt on your jeep needs to be VERY VERY tight or it will make noise on acceleration when it is "loaded up" like when the a/c is on or the rear defroster is on, i take a light and look for witness marks on the pulleys and jack screw and crank the belt till they are no longer visible then 1 more turn, the tension spec is 175 pounds belt tension measured with a belt tension gage, thats a hellof a lot of tension but is needed serpenine belts need a lot of tension or they slip and squeal under load but they last a long time compared to old style "v" belts which required little tension comparitivly
Hello Bill...this problem has persisted through 3 seperate belts, including a Gator Grip from goodyear...it's not the belt. As I stated, I've had a Cherokee my whole driving life and can replace these in my sleep. I have NEVER had a cherokee that even noticed when the headlights went on, even with the defroster, blower, and radio cranked. There is another issue here.
So, any other ideas?
have you checked the belt routing? here is how it is supposed to be,the routing was changed in 1997, if it is correct check pulley alignment, when did the noise start? before the alternator or after, also look to be sure the belt is on all the pulleys correctly and with the belt off check all the pulleys for excessive play pay close attention to the waterpump pulley and power steering pump they are common "failures" the powee steering pump USUALLY leaks but not always at the front bearing and seal and cause a squeal or noise
We are getting sidetracked by the noise here.....forget the noise, my issue is with the voltage drop...if I can solve this issue then there will be no noise. Turning on my headlights should not cause my voltage to drop from 14 to 12...and it's not just my headlights, defroster, blower, etc. all cause an above average drop. What is the onboard computer supposed to do when demand is high? are the RPMs supposed to go up?
For what it's worth, the belt is routed properly, and there is no fraying on the edges to indicate a misaligned pully.