Hello my 2003 Dodge Intrepid was running great.

And you're still driving it when it has been telling you it's about to die completely and let you sit on the side of the road? The charging system has stopped recharging the battery and it will go dead in less than an hour; much sooner if you have the lights or heater fan on and use the starter repeatedly. The fact it has lasted this long is a testament to how good your battery is.

Have the charging system tested and expect to need a new alternator. The brushes commonly wear out and cause intermittent operation. They can often be replaced without even removing the alternator from the engine but conscientious mechanics will only replace the entire assembly.

What was the code number or description?

When you say your husband is going to work on it, do you mean just throw on a new alternator or is he capable of doing some diagnostics on it? Chrysler always had the easiest charging systems to diagnose since the early 1970s, but they changed one important detail starting around 2000 or 2001. I've been trying to develop a quick test for the new systems that would make diagnosis as easy as it used to be, and I think I came up with it last night. If he has a digital voltmeter and knows how to use it, I'd like to know what the two voltages are on the two smaller wires on the back of the alternator when the problem is occurring and when it is repaired. Those readings have to be taken with the engine running.

That just means there is a diagnostic fault code stored in the Transmission Computer. Almost any code in the Transmission Computer will set the 700 code in the Engine Computer and turn on the Check Engine light. That is because if the transmission slips or sticks in the wrong gear, or waits too long to up-shift, it can have an adverse affect on emissions. Any code that could affect emissions is required to turn the Check Engine light on. There are a lot of other codes that do not turn the light on.

Code readers used by the auto parts stores that read them for you for free usually do not access anything other than the Engine Computers so you might have to visit a mechanic with a scanner that can read all the codes.

Be aware too that if there's a charging system problem, system voltage will be low. There are dozens of computers on your car and they will start to do weird things. In the case of the transmission, it is electronically-controlled with electrically-operated solenoids. When they try to run on low voltage, they will not open and close properly. That alone can be detected as a problem and set a fault code. The computer can also set false codes. If the problem is serious enough, the transmission will default to "limp mode" where it stays in second gear. That is to allow you to drive it slowly to a repair shop without needing a tow truck. Don't try to drive at highway speeds with it stuck in second gear.

The anti-lock brake system is a perfect example of what is happening with the computers. It has to cycle numerous solenoids on and off very quickly to prevent skids and the computer knows it can't do that properly with low system voltage. In response it turns the system off and turns the warning light on to let you know.

The first thing to do is check the charging system. With intermittent problems like you described, that testing must be done while the problem is occurring, meaning the "battery" light is on while the engine is running. With it running, measure the battery voltage. It must be between 13.75 and 14.75 volts. Expect it to be low. If it is, that's where the two voltages on the two smaller wires on the back of the alternator will be helpful to know.

Was the battery light on during those tests? If it was, and the alternator was okay, that would leave the voltage regulator inside the Engine Computer. If that is not working, which is very uncommon, it would have to have been bypassed to make the alternator work. That's not something most mechanics know how to do.

Another way an alternator can fail is by having one defective diode out of the six of them. That will reduce its output to exactly one third of its design value and that's not enough to run the car's electrical system under all conditions. It can however, keep you going for days or weeks as the battery very slowly discharges. The typical 90 amp alternator will only develop around 30 amps, and the rest of the car's needs is made up by the battery.

A professional load test is required to identify a bad diode. If you already had that done, did they give you a printout? The things to look at are output current and "ripple". Output current must be at least 90 amps. Some alternators are designed to develop up to 120 amps. 30 - 40 amps is no good, but as I said, that can get you by for a long time. When one diode is bad, ripple will be very high, as in a few volts. You might hear a loud whine on AM radio too.

The only other thing that could cause the battery light to turn on intermittently is a slipping serpentine belt. A spring-loaded tensioner could be weak or rusted so it won't pivot freely, but snow or ice on the belt would be more likely. Usually that condition won't last very long.

Letting it charge for 30 minutes was the right idea but when it died right after that, I would have suggested the battery had a shorted cell. The next thing, when you said it was just replaced, means there was a bad connection on the jumper cable and the battery wasn't really charging for that 30 minutes. That's why it died right away.

Bad cable connections happens to me all the time. The way to tell is to watch the brightness of the under-hood lamp or turn on the headlights and watch them. Wiggle each jumper cable clamp, then leave them alone when the lights get brighter. If you're using a battery charger with a current meter, the meter will stay on "0" when there's a bad connection.

Be aware too that batteries give off explosive hydrogen gas and wiggling the jumper cable clamps can cause sparks that can ignite that gas. At the very least do not hold your face close to the battery.

That mechanic who said "not to worry this car is known for the battery light coming on for no reason." Is absolutely wrong. If that were true we would be telling that to people on this site all day long. The fact is, we're helping people all day long with cars dieing due to dead batteries. The light turns on in response to a problem and some of those problems are not readily apparent. One third of an alternator can fail which leaves you with only ONE third of its rated output as the most you can get and that's not enough to run the car's entire electrical system. The battery has to make up the difference. A simple and quick voltage test at the battery will not show that and it will look like the alternator is working fine. Only a load test will show that. The common 90 amp alternator will only produce around 30 amps. If you can catch it when the battery light is on, you can do somewhat of the same thing by measuring the battery voltage, then turning on as many things as possible. Turn on the bright head lights, the heater fan on high, and especially the rear defogger. A good alternator will be able to keep up to all of that with the engine idling, and the battery voltage will remain between 13.75 and 14.75 volts. When one third of the alternator isn't working you will see the battery voltage drop as you turn on more and more things. Raising engine speed slightly makes a good alternator more efficient and more productive and will bring low battery voltage back up to normal. Raising engine speed won't help an alternator with one third of it failed