silron

hello,first time here.
i own a 1998 jeep Cherokee sport, 6 cyl inline, 4.0L ,4x4.this jeep had serve me very good and still is.it has 179000 miles,just replaced the alternator with a used good one.however after reading the repair manual i am for to rebuild the broken one and save for spare. i need to find a place to find the brush/holder.i got the regulator,just need a new brush.if anyone know a place please let me know?

89whiteXJ

I thought the regulator for the 98 was in the Computer? You stated you got a regulator.

5-90

The regulator circuit is in the PCM - you can't replace it by itself.

The brushes and holder (which is probably what you're referring to) and the electronics in the rear case (rectifier, filter diodes) are probably no treadily available at parts houses anymore - check with a local starter/alternator shop for replacements. Alternatively, you can ask at a local mom-and-pop parts house, and see if they can order those parts for you (don't bother with the chains - probably won't happen.)

When you've got the thing open and you're inspecting parts, I suggest a light hit with some emery paper or crocus cloth on the sliprings on the rear of the rotor, and flush it clean with electric motor cleaner. They're usually a bit varnished from running, and it's amazing what two minutes spent on that little detail can do!

silron

sorry,is the other part next to the brush holder.i was thinking that was the regulator.i removed 3 parts- 1-the brush holder.2-the metal plate that connects 4 wire,and then the other

5-90

Quite all right.

There are simple electronics that are present in every alternator, usually in the rear case.

These simple electronics are the rectifier diodes that convert the AC generated by the alternator in to DC that can be used by the vehicle (since the primary electrical storage of the vehicle is a battery, it has to use DC current - batteries can't store AC. However, AC has a higher "density of generation" than DC - the old automotive generators of the 1950's were about the size of three alternators ganged front-to-back, and were only good for up to about 40A or so - on the more powerful ones. And, they were heavy (about a pound an amp, generally.)

A 40A alternator can be made quite small and light - which reduces the space needed underhood, cuts rotational mass (and therefore drive power per amp,) and allows it to cool more easily.

A generator that would do 200A is unheard of - 200A alternators are commonplace.

Also, an AC dynamo is simpler of construction than one for making DC.

Chances are, the electronic gizzy you see in the back of the case is the rectifier pack. Ask for it the same place you go for the brushes and holder - an outfit that can get one can generally get both. A full-wave rectifier pack typically has four terminals (two AC in, two DC out.) There may be an RF/EFI filter back there as well, but it likely has only two terminals (it's typically distinct from the rectifier pack, as it only needs to permit current to flow, rather than convert it.)

If there's a largish metal bit on the rectifier pack (likely) or filter (not so much,) it's probably a heat sink - clean it thoroughly, reapply thermally conductive heat sink grease (get this from an outfit that sells computer parts - it's commonly used on CPU/video chipset/fast RAM heat sinks) and reinstall. Be sure you do this - failure to use heat sink grease can result in premature component failure, failure to reinstall the heat sink will result in premature component failure!

93gc40

If you are having trouble understanding what Kelly is saying. Find an auto electric shop and have it rebuilt and rewound to a Higher output.

89whiteXJ

You can do it if you diconnect it from the PCM and use and external regulator.

5-90

Yes - but as I've mentioned elsewhere, you'll still get a persistent code because the PCM will see the regulator signal not doing anything, and we haven't figured out how to fool it yet...

89whiteXJ

Got ya.