I have a 1999 Jeep Grand Cherokee limited,V8 Quadra-trac which dies on the road; dash gauges drop; "no key" lite displays on dash. Restarts after cools. Two codes P 0443 and 0308 are showing? help

are you on dirt? or pavement...????????????????????????
we cant answer until you answer what 4wd option you have.
if that makes no sense, then read the operators guide,
it tells you what's there and how to use it.
read that first, then ask questions,?
and if Part time 4wd?, it';s not to be used on dry pavement only ICE.

eg:

4WD: Select-Trac (or older Select-Drive has a slip coupling too, NP129/229) is AWD in that, "the "4Hi" setting the drive shafts were coupled together using a viscous-type coupler " this anti wind up slipper"
Watch out for exception 1: Select-Trac NP228 based jeeps, it does not have a viscous-type limited-slip coupling. It was used briefly in 1986.
Quada-Trac is full time 4WD (not in lock mode) has a real center differential to shift torque between front and rear. This is the best system , not just a slip clutch as above. Then went BACK to the slipper in 1980. (odd huh?) Up to 1998.
Quadra-Trac-II "4-All Time", "N" or neutral, and "4-Lo". In "4-All Time", torque is applied to the rear wheels under normal driving conditions.
If the rear axle starts rotating at a significantly higher rate than the front axle, hydraulic pressure builds up in the gerotor oil pump and causes the clutch pack, to progressively transfer torque to the front axle, until both axles return to the same speed
Quadra-Trac I was introduced in 2004-10, same as above but is automatic with no driver controls ,like above.
The Quadra-Drive system was introduced in 1999 and is based on the Quadra-Trac II system but adds limited slip differentials (the best full time system ,with great traction to all wheels all the time) 1999 to 04.
Quadra-Drive-II has electronic limited slip differentials or ELSDs 2005 up.

which system?
we cant guess what is In YOUR CAR, ever.
you must SAY. or RTM, in the glove box.
and why are you using 4wd on dry pavement, now>?


4WD: Select-Trac (or older Select-Drive has a slip coupling too, NP129/229) is AWD in that, "the "4Hi" setting the drive shafts were coupled together using a viscous-type coupler " this anti wind up slipper"
Watch out for exception 1: Select-Trac NP228 based jeeps, it does not have a viscous-type limited-slip coupling. It was used briefly in 1986.
Quada-Trac is full time 4WD (not in lock mode) has a real center differential to shift torque between front and rear. This is the best system , not just a slip clutch as above. Then went BACK to the slipper in 1980. (odd huh?) Up to 1998.
Quadra-Trac-II "4-All Time", "N" or neutral, and "4-Lo". In "4-All Time", torque is applied to the rear wheels under normal driving conditions.
If the rear axle starts rotating at a significantly higher rate than the front axle, hydraulic pressure builds up in the gerotor oil pump and causes the clutch pack, to progressively transfer torque to the front axle, until both axles return to the same speed
Quadra-Trac I was introduced in 2004-10, same as above but is automatic with no driver controls ,like above.
The Quadra-Drive system was introduced in 1999 and is based on the Quadra-Trac II system but adds limited slip differentials (the best full time system ,with great traction to all wheels all the time) 1999 to 04.
Quadra-Drive-II has electronic limited slip differentials or ELSDs 2005 up.

You need to be more specific. To start, which 4 wheel drive system your jeep has? (Select Trac, Quadra Trac II or Quadra Drive)
Then: does it never work, or only in 4-Lo?

a bad wheel speed sensor or not matching tires

It can be the computer or lose wiring in the computer

Could you tell me what selection you have on your 4x4 shifter?

You have 4 high (full time) N 4 Low and nothing else?

Quadra only sends power to the front axle when it is needed, it uses a hydraulic unit that senses slip then send power to the front.

You also need to make sure your getting it in to gear right, for me I found that getting to 4 low can be hard as they tend to bind, move the 4x4 shifter to N take your foot off the brake and pull it into 4 low, do the same getting back out.

I have owned every 4x4 Jeep T case in Grands from 93 to 02 they offer fantastic traction and options and are strong.

Make sure your T case fluid is full, if you have never changed it DO SO, as dirty fluid plays hell on them, if you do have Quadra trac you need to get the correct fluid for the case, go to your Jeep dealer and get it, DONT put trans fluid in as this dose not work right with the system.

If you want "Locked" run the system in 4 low, as heavy off road in 4high with Quadra is not the best for heavy off road, use 4 low to that.

If you need more help just ask, I hope this worked.

1993 2HI N 4LO, 1998 5.9 LX Quadra trac with limited slips 2000 2HI, 4HI full 4HI part N 4LO 2002 Limited with Quadra with Vari-Lok differentials.

Does the whining sound like it's coming from the power steering? This usually is an indication that the power steering fluid level is low.

universal joint on the driveshaft may do this !
check transmission fluide as well.
good luck

the crank sensor is in the lower passenger side of the block....a cam sensor can also cause this...it would be wise to have someone pull the codes from the pcm...it could save you a lot of money and headache....most parts stores do it for free