I have been having this issue for four years and have narrowed my search to 3 or 4 things. Mind you. I know a lot about mechanics but never learned how to pull apart and piece together a car. I’m afraid if I try I’ll ruin it. That’s why I’m here. My 2004 Nissan Pathfinder LE, 4wd is doing the same thing it has done for the past 4 years running. I’ve owned it since late 2006 and taken it in for a couple recalls. I’ve had the alternator replaced, 2007. I’ve replaced the battery 3 times, but this is the interesting thing. Since late 2009 I’ve noticed that when it gets cold or is humid/rainy outside there’s a squeal. BAD SQUEAL. I thought, maybe the belts are bad. Sure enough I needed to replace the belts. A year goes by and the same thing, belts. Now the same thing happens but another symptom pops up: my car stalls at the most inconvenient times, but only when using too much electricity. Another year. This is where the strange thing happens. My electrical systems begin to go haywire when I have the headlights on, but only when it squeals. I take it back to the mechanic and explain what is happening and he takes my car for 2 days and does his “inspection.” He then replaces the belts and the battery. Thank god the battery was on warranty. Haven’t paid for a battery since 2010 but this is getting ridiculous. My car then runs perfectly for about 6 months. Then 1 rainy day, SQUEAL!!! No electrical problems so NOW I know that it must be the tensioners/pulleys. I call him and he gives me the nonchalant, “Nah, I took a look. You’ll be fine.” I am in the process of moving back to TX from CT at the time so I just push it to the side since I’m loading everything into a 36’ trailer and driving cross country. Now, a month later my electrical systems are going kooky again. This is what I mean: my automatic door locks lock themselves and unlock themselves randomly. I hear a whirring sound, highly pitched, that I can’t pinpoint since I’m driving and can’t move about. my check engine light goes on and off with varying lengths of time in between. My headlights dim unless I rev the engine enough to make the alternator turn faster. Then, I realize my car starts to buck like a broncho. Jerking when I take off and taking a bit to cross an intersection after a stop, but after about 20mph or so it rides ok until the next stop. Then at night, with the headlights on, the airconditioner/heater going, and the radio on it stalls. I turn it back on, move to the side and after a few minutes it’s ok. So now that I was back in TX near my dad, an “excellent’ mechanic by everyone’s opinion, I ask him to look at it. He does and says, 'oh, you need to clean the terminals on your battery, they’re corroded from the salt from all the winters in the northeast.” I do so and the thing works like a charm. FOR 3 DAYS. Then it’s worse. He takes my car and lends me his awefull PT cruiser and replaces the belts and inspects the entire electrical system. He cleaned everything and that was that. My car has been fine for the last 6 months. He told me that the whirring sound was my fuel pump b/c it wasn’t getting the proper supply of power it required. Well, just last night I was driving home from work, after dark, and my car started bucking like a broncho again. I turned off the heater and the radio and still had issues at stop lights but it ran fine on the interstate on the way home. I drove to an interview this afternoon and no squeal or problems, but the heater and radio were still off. What can this be if no the belts, if not the battery, if not the alternator, then what? the computer? the pulleys/tensioners?
Squeal and electrical problems…usually points to an alternator.
He does and says, 'oh, you need to clean the terminals on your battery, they're corroded from the salt from all the winters in the northeast."
I live in the North East (New Hampshire) and I’ve never had that problem caused by salt.
I’d start looking for a new mechanic.