I'm about to drive the 02 off a cliff (long, long)

[ths916m3]

Alright here is something you all can help me ponder.

My 1973 2002 45 amp alternator died a little after I got it in 2001. So I decided to upgrade to the 320 65 amp alternator, that went dead a few months ago.

I went ahead and decided to upgrade again and got a 90 amp 318/325 alt. to replace that....this is where the problems start.

When the 65 amp alt went out the charge light would stay on all the time. I checked the voltage at the alt. and it read what the battery read.

I replaced it with a rebuild 90 amp unit from ebay and got the same thing, light still on and no voltage. I disconnected everything and brought the alt. to Kragen, they tested it and said its fine. Brought it home looked it over again and hooked it back up....still the same, light still on no voltage from alt.

So a few weeks ago I ordered another rebuilt 90 amp alt. this time from Bosch....and.....gosh darnit, still the same. I was ready to throw in the towel, but M3 starter sounds so cool though, thats another story.

Please what the hell could be wrong? Connections all look fine, Charge light is working (Always on), Checked voltage at the alt. with the car running and it reads what the battery reads (usually about 12.2 or lower). I am at a loss, if I cant get the help here I guess I will bring it to the shop as my last resort.

[Guest Anonymous]

Why don't you try going back to the 65 amp and see if all your problems still exist?

[JohnN]

alternator and the block. Build a new cable with nice thick wire, solder it to a set of new lugs, and make sure the lugs are in firm contact with nice clean metal on the block (or head). Double check also the ground between the block and the chassis.

Bet that's your problem.

Cheers!

John N

[Beaner7102]

is the voltage regulator dead? Have you asked an Auto Elec dude to check it all out in the car with it running, not seperate items?? Half an hour of a pro's time could have saved you buying 2 bigger alternators. FWIW Beaner7102.

[Ricola]

First have the battery tested for staying power. Fine a shop with a load tester. It should read around 12.6 or so prior to loading and stay above say... I think 10.8 volt under a 30 second load. Too low of a static reading can be a sign of a bad battery. My numbers may be off. I haven't had the problem for many years now.

Next check cable resistance. You could have corrosion inside the shielding.

Then and only then check your alternator. With the car running check the battery. you should get somewhere in the area of 13.6 or better with the lights on.

I got tired of the Bosch failure rate and modified a GM Delco one wire alternator in place of the Bosch. End of problem.

[Chris_B]

If your alt. tests good outside of the car, but you are not getting output with it spinning up in the car, then either the (i) alt. is not grounded properly (check for continuity between the alt. body and chassis (ground post on battery will due- ohmmeter should read close to 0; if you see more than an ohm or two, then follow John N's instructions for ground cable), or (ii) you are not getting +12V at D+ (the blue wire from your indicator light). Check for the presence of system voltage at D+ with your ignition switch in the on (run) position, but motor not running.

The fact that your charge indicator light stays on is confusing... make sure the "blue" wire is connected to D+ on your alternator. Note that the light would stay on if that wire was connected to some other grounded point.

[Mike Self]

the two wires that go to it are both + wires...one from the battery, one from the alternator. When both are doing their job, the two +12 v inputs cancel each other out, and the light stays off. If either the battery or the alternator aren't functioning properly and/or the wiring on either side isn't up to snuff, the light will come on--dim for a smallish fault, bright for a serious problem. Oh...and make sure the bulb is the correct one.

Check both wires that lead to the charge light and see if you have +12 with the engine running. If not, trace the no voltage wire back to its origin to see if it's the wire or the unit (batt or alt)

good luck--post what you discover to further our '02 education

mike