Altenator question ????

[capj]

Here is a question that I hope someone has an answer to.

I have a 1993 and this has happened three times now. The altenator stops charging according to the volt meter gauge..... [and yes I have verified that it is not a bad Volt Gauge with a handheld.]

The altenator when removed checks out good, nothing wrong with it. I only removed it once and had it checked. So, I just charged the battery when it began to get low....... I was just driving around town at the time anyway. This lasted about two weeks and then it just started charging again.

This has happened two more times for a couple of days and then it starts charging normal again.

Has not happened in a couple of months come to think of it.

Anyway...... what could be the cause of this????

Any help is appreciated. :thumbsup

[keydl]

The regulator is in the PCM and the cause is often as simple as redoing the ground connections, or check the speed sensor and the sensor at the vibration dampner. The A/C quits if the sensors are not workingIf that section of the PCM is not reliable then an old style voltage regulator can be wired in, a relay from a key on that supplies the regulator on to 1 of the rotor leads. The other rotor lead is grounded and the regulator should be grounded to the alt frame.Poor grounds are the most common cause of electrical malfunction, bad battery terminal connections account for about 70% of the AAA's no start calls. About 1/2 of the electrical problems that I see started as a poor ground, from a tail light tattle that insisted the working tail lights were bad to a no start because of dissimular metals corrosion that stopped when I moved the ground from the aluminum valve cover to the cast iron block.keydl

[Mopar1973Man]

I would check from the back of the alternator to the batteries for bad wiring and bad connections. I've seen voltage drops as high as 2 Volts from the alternator to the battery because of bad wiring.Keydl is right on the money about the PCM controlling the alternator. But the alternator also has carbon brushes for the field that wear out over time and might need to be replaced. LOTS cheaper than buying a new alternator... You need to check to see if the field is functional and had flow of current... If the field is open circuit there is NO CHARGE! You could pull it off and have it bench tested too...

[keydl]

One of the symptoms of short brushes is intermittent operation, same with thrown solder on the slip rings. Because it is not currently broken, it may be that back probing the field leads with sewing pins and wires to the dash so that you can read the voltage. PCM or harness fault is 0 volts, open circuit on the rotor will give over 6 volts. I may have to go out and read mine - but not today :)One other thing if the ground ( return path ) is not in good condition it can cause an amazing assortment of other problems as the ground path goes through the transmission or throttle linkage. One ate the clutch linkage, the engine ground strap had been left off and the customer rode the clutch but his daughter did not. The link rods were nearly eaten through and it would not charge more than 5 A with the clutch up, ridding the clutch it was normal generator function. Put a ground strap from the block to the frame and it went to work. Any two major parts of an alternator go out and it is normally cheaper to replace it. Rotor, stator, diode set, frame are major, pulley, brushes and bearings are small and cheap so they can be in the 4 wheeling parts stores.keydl

[capj]

Thank's guys. Sorry for the late reply but I have ben real busy at work and also limited computer access.I will go out this afternoon and check out the things you suggest. Since I last posted it did it once for about an hour ???? But has been working fine ever since. :confused: I will check out the things ya'll have suggested though and see what I find. :thumbsup Mike, I had it bench tested a while back and it check out fine.Later,Chuck

[Mopar1973Man]

Well the charger system is rather simple... * Batteries (storage of energy)* Alternator (charging source)* Voltage regulator (Control charging rate)So... Check to see if there is field energy. If there is no field energy the alternator will not charge. Field voltage will vary up and down to control charge rate. But there has to been voltage on the field lines. Alternator has dio packs and brushes too. I seen a few cases where diode packs have broken loose and would charge and quit. Brushes that are near there life limit could have a on/off effect too. Basically turn the field off and on randomly. Worse case would be the regulator in the PCM is acting goofy either because of bad grounds or internal problems...

[capj]

Bingo boys............. it was the brushes.

Thank's for all the good info.............. :thumbsup

[Mopar1973Man]

Glad to hear you got it fixed cheap! Right On! :thumbsup