I've tried searching, and have not found anything that explains this. Here are my symptoms:

Voltage gauge will dip from around 14.5-15 down to 12 when at idle or coasting.
Car did die twice when putting into gear (reverse) and does seem just slightly hard to start.
The headlights dim unreasonably at idle or when coasting.

Symptoms are worst when coasting, but present at idle.

Also, in case it has anything to do with it, when starting from a stop, occasionally, it takes a second to actually start moving, the engine revs, but its like the tranny isn't engaging to move forward.

I have replaced the battery (which was bad), and had the alternator tested (which was replaced not too far back) and it checked out. Connections are squeaky clean. Any ideas?

Also, while people are reading, there is a squeak coming from the front left that is quite loud. I've never had 4WD before, so I know nothing about torsion bars. I'm used to springs squeaking. I have had a lube job done. What tends to squeak?

Thanks in advance.

 

It seems that you have a few problems.
1: Have you had the alternater tested on the vehicle?
What is the condition of the belt and the belt tensioner?
Is the idle speed low (what's the RPM)

2: Have you checked the level, colour and smell of the transmission oil?

3: Is the squeak while driving straight or cornering, over bumps, with or without the brakes applied?
Will it squeak if you just grab the bumper and start the front end bouncing.

If you can answer some of these questions, it may help to diagnose the problems.

 

1
a) I have not had it tested on the vehicle. Will do this weekend. It was bench tested.
b) The belt is a brand new Gatorback about 1000 miles ago (the original squealed), the tensioner seems to be pretty strong (is there a real test for this besides just seeing how much pressure it takes to loosen the belt?), I did replace the idler pulley as well at the same time.
c) Idle doesn't fluctuate too much but it does tend to dip to just above 500 every now and then, but mainly pretty steady around 600 RPM. Doesn't stick out in my mind that they coincide, the voltage seems to be on its own schedule for the main part.

2
Have not checked the tranny fluid yet. I just got it recently. That must be one of those DUH things. I've been having those moments lately. Will do as well this weekend.

3
Squeak is definitely just a movement squeak. All of the above, over bumps, standing in front pushing down, turning the wheel while stopped, you name the motion, it squeaks, right from the left side.

Thanks again!

 

A little update, I have decided that the voltage dip is definately not coinciding with the idle RPMs (unless the gauge is terribly inaccurate) as it seems very steady when the problem is occurring. However, revving the engine to above 1200 does fix the problem (the additional output of the alternator must overcompensate for whatever demon is causing this).

Also, just to throw into the mix just in case it has anything to do with the above, I haven't been able to get more than 13mpg since I got the truck, and I do about 60% highway, 40% city.

Also, checked the tranny fluid, its all there, doesn't smell to burnt, but no close inspection of it til its warmer.

 

Update again, put a regular voltimiter on it, and it hits its low at approimately 11.85 volts. Unsure of what the devil is going on.

 

11.85 Volts? THe alternator is not charging at that point. If battery voltage gets too low, the computer will get REAL confused, and stalling would probably be the least of it. I am kinda curious if the relatively low idle is causing that, or, vice versa. Seems kinda odd. Is the SES lite on?

Some info on the truck would be good, year, engine, mileage, etc.

 

The SES came on about two months ago, came back as p0171 and p0174 too lean in banks 1 & 2. Hasn't come back since I cleared it. I cleaned the MAF at that same time. I'm pretty sure it did the voltage dip thing before and after.

Its a 2000 Jimmy 2-Door 4x4 4.3l with 65,000 miles. Thanks again!

 

What exactly is a low idle? When its cold out, it naturally idles higher for a while. Even at 800RPM, it still dips a little. Nowhere near what it does at 600, but its noticeable.