IS IT A BAD BATTERY OR ALTERNATOR???

Couple things come to my mind, is the battery or alternator. Once the car is running it then shifts to the alternator for power. You could have a loose cable to to/from the battery or alternator, a thermal short in the alternator. To check these our just inspect the wiring from the alternator and battery, ensure there is no corrosion and the cables are tight. If so, you can test the alternator by running the car and putting a multi-meter on the battery, it should read about 14 volts when the car is running, if not then the alternator is bad. On the battery side visually look at it, if it is not square or the sides are bulged out the battery has an internal short. Both of these can be check at your local auto store, ie AutoZone. O'Riley's, etc.

That is the simple, the harder would be another sensor, Here is a link to another site that has a Jeep dying while driving with troupleshooting

did you check that battery is charging with a multi meter ? could be that your alternator has a fault . Icheck battery voltage with engine off and running , voltage should be approx. 12.48v with engine off and around 14v running . if no increase in voltage when running brushes in alternator will need replacing .

check your the engine module(computer chip could be going bad)

Sounds like a bad connection. The alternator only charges the battery, so if it or the voltage regulator in the alternator fails, the battery would slowly run down, not die all at once.

have someone turn the key while you listen for the fuel pump to come on in the fuel tank. it should only come on for a few seconds if not than your fuel pump is bad.

Jump start your van, with a volt meter check voltage at battery with engine running and jumper cable disconnected, you will be checking alternator out put voltage there, should have a reading of not less then 13.5 volt's, if less replace alternator, alternator is not hard to replace. two or three bolts is all that holds it in place, don't forget to disconnect battery before removing alternator.

Unfortunately there could be many causes for premature battery death. The top culprits in ALL cars would be a bad alternator that isnt putting out proper charge to recharge the battery, a bad battery itself (if yours is factor and never changed then its time), or you could have poor connections. Then there are some GM specific things such as a bad Brake Control Module, Bad Fuel Pump, etc. Lets start with easiest first. If you are not handy or dont feel comfortable under your hood then there are alternates to the below

1. Check the battery cables at the battery posts (yours is side mount) and make sure they are tight, wont wiggle or twist back and forth. If they do tighten them

2. Check the alternator wires to make sure they are firmly attached, no loose nuts or bolts, etc. Tighten but dont over tighten and strip or break

3. Check for corosion on battery, battery tray, battery cables. These can drain the battery. If you have corosion then you can purchase CRC battery cleaner with Acide detector at local parts store to spary and clean.

4. At night go to your car and see if any lights, such as glove box, trunk, hood, dash, etc are staying on. Sometimes trunk or glove box lights stay on but since we dont look in either often we dont notice.

5. Crank the car and have someone stand in front as you are in the drivers compartment. Turn your lights on and then bright. Depress the brake pedal and ask the person if the lights dim or flicker at all. Also look at your instrument panel and see if your lights there are pulsing, etc. This can indicate a bad alternator

6. Turn on radio and see if you hear a hum (not static) but a low hum or whine. This could be a bad alternator.

An alternator has DIODES in it and they can go bad causing it to fail.
An alternative to above is to take it to your local Autozone, Advance, Napa, or Oreilly auto parts store and they can do a "load check" on the battery and alternator to see if they are functioning properly as well.


Now for the GM issues.

GM cars are known, even the Corvettes and Cadillacs, as having bad fuel pumps, Climate control, and ABS sensors.

1. ABS control module can go bad. A common diagnosis is to listen and see if you hear a hum comin from middle to rear of car on drivers side, near rear wheel well, CAR OFF. If the car is off and you hear this hum. Its possible the ABS module is bad and will need to be replaced. They are very expensive to replace unless you find a reputable place to have yours rebuilt. If you are a GOOD DIY person and comfortable with cars a good site is www.absfixer.com. You can disable the ABS module by pulling a fuse in the engine fuse block. Im not sure the diagram for your model. Check your owners manual.

2. Fuel pumps can also go bad and continuously run. If its running it will drain a battery. You may not have symptoms in the running of the car if fuel pressure isnt affected. Listen for a similar him in same area (mid to rear) of car. Hum will be with car OFF

3. Climate control in your Caddy is very advanced and uses a climate control module and not typical switches and wires. All computerized. If you've noticed a change in performance of your fan output (low air output or higher output at lower settings) Change in air temperature and temp not matching what you have set on the control Cold=Cold.. Hot=Hot.. then its possible this is a drain.

Unfortunately the last three are somewhat easy to diagnose, but hard to fix. YOu will require a good mechanic or your dealer for these repairs.

FYI.. the same site for your brake module rebuilds teh climate controls as well.

Good luck

this is caused by a failing alternator. Kragen auto and Autozone tests these for free.

sounds like the fuel pump has gone out on it. To test your fuel pump have someone turn the key on, but do not start, and listen for a humming sound by the gas tank. It will only last a second or two. If you hear nothing then your pump is bad and will require removing the gas tank. If you do hear it try replacing the fuel filter and see if that helps.

When you test the alternator in the way you said you did. By removing the positive cable, you damage the ECU or computer. You are probably going to have to replace the CPU or ECU both mean the same thing. You also damage some resistors and other electronic components on the alternator itself when checking it this way. In the old cars , that did not happen because they had no CPU or ECU. Now it does.