1999 Jeep Grand Cherokee...numerous problems

Well some of you may remember me when I was having the problems with my Oldsmobile. You all helped me fix those problems. Now I'm back with a few more on the Jeep that I recently bought. The Jeep is a 1999 Jeep Grand Cherokee Laredo. The engine is a 4.0ltr 6 cylinder engine. Here is a list of the problems.
(1) First. When I am going down the road in the night I notice that the lights dim when the fan kicks on to cool the engine. I am pretty sure it is the alternator, but just want to be sure. Is there a test I can do myself to test the alternator?
(2)Second. When my car is idling or whenever I am driving I hear like a whistling coming from the serpentine belt area. I put soapy water on the serpentine belt and the noise dissappears. Time for a new belt?
(3) Third.The abs light is on, but I am unsure why. I was wondering if there was an easy way to figure out what it is?
(4) Fourth. When I am driving down the road and take a corner or hit a bump or something there is an extremely loud clunk that comes from underneath the Jeep. It is really loud. When the clunk happens you can actually feel it inside the car...any ideas?
(5) Fifth. When i switch to my four wheel drive then switch back to two wheel drive my car stays in four wheel sometimes. When I am in two wheel drive just after switching from four wheel drive and turn the car kinda sharp it feels as though the jeep is still in four wheel. Any ideas here?
Someone please help!!!!

(1) First. When I am going down the road in the night I notice that the lights dim when the fan kicks on to cool the engine. I am pretty sure it is the alternator, but just want to be sure. Is there a test I can do myself to test the alternator?
(2)Second. When my car is idling or whenever I am driving I hear like a whistling coming from the serpentine belt area. I put soapy water on the serpentine belt and the noise dissappears. Time for a new belt?
Does sound like the belt is slipping - when more current is needed the alternator requires more effort to turn and the belt may be slipping when the electric fan turns on.
Check the Belt Tensioner, it may not be keeping the belt tight enough.

Thanks! Where is the belt tensioner? Is there a way to test the alternator for output?

This should help:
http://www.wjjeeps.com/serpentine.htm

You can test the alternator with a multimeter.

Ahh yes the famous Cherokee clunk. Check your stab links. Mainly the front. Cant begin to tell how many I have changed.
Check your pullies for rust. You will notice it on your belt. Clean pullies. Install new belt.
As much as I hate to promote them go to Autozone they should be able to test your alt there while still in vehicle.
4 wheel problem, are your front and rear tires a matched set? Made a differance on my 95 Ram and 96 Cherokee. Same problem, tires would be a diff manufacturer and be the same size but be off just enough to put a small bind on the actuator or the transfer case.

Stab links? Never heard of them. Do any of you's know where the abs sensors are on the 99 Grand Cherokee?

Stab links? Never heard of them.
Steering stabilizer. Just get it on a lift and start looking for loose parts -- grab and wiggle bushings, brackets, connecters, etc.
Do any of you's know where the abs sensors are on the 99 Grand Cherokee?
Attached to the Hydraulic Control Unit under the hood, in front of the master cylinder.

Stabilizer links on the front stabilizer bar. You dont need a lift just follow the bar to the wheels. At the end of the bar is the link. You should be able to turn the front wheels each way and see the links. If they are broke it will be very visible.
That may have a sensor at each wheel. You can start by looking for wires running to each wheel bearing area. I looked up the parts and It looks like there is one at each wheel.

Thank you all for your help! I just want to fix it the cheapest way possible.

Does sound like the belt is slipping - when more current is needed the alternator requires more effort to turn and the belt may be slipping when the electric fan turns on.
Check the Belt Tensioner, it may not be keeping the belt tight enough.


How do I tell if the serpentine belt is tight enough?

How do I tell if the serpentine belt is tight enough?
It's in the link I posted above.

Do any of you's know where the abs sensors are on the 99 Grand Cherokee?
Just to clarify, the ABS controller module is attached to the Hydraulic Control Unit, the ABS wheel speed sensors are at each wheel.

Bob,
the abs speed sensors are not parts of the hub are they? I am hoping not. Can I just go to the local autoparts store and buy the sensor? How do I know that it is the sensor without hooking it up to the scan tool?

I don't know if the wheel sensors are available after market, but before you buy any parts, retrieve any fault codes via the following:
Put the key in the ignition, then turn the ignition key On then Off 3 times in succession. Leave the key in the On position after the 3rd On. (On/Off, On/Off, On) The odometer will then replace the mileage with one or more fault codes, or if none are stored, "done"

#1-2 I would go with the belt being your problem.
#3. see if the fuse is in for the abs.
check for codes.
#4. stearing stablizers, shocks or springs would be my first inspection.
#5. When you take it out of 4x4. stop and back up 10 feet. exspecally in town driveing. slipery roads will allow disenguagement. And yes, tires are a big issue. Make sure someone didnt do a swap. two tires or something. a 4x4 requires all 4 tires be the same.

all 4 tires are the same. Thanks All!!! Im going to run out now and try to get a code.