Charging system problem (HELP!!)

[paslantnose]

Guys, i need help with the charging system problem i'm currently (no pun intended) having.

I've searched the threads extensively and even printed Jim Thoresen's diagnostic breakdown to no avail.

A month ago, the alternator failed, we pulled it off and sure enough, a bruch had broken and wiped out the commutator.
OK, a new alternator was installed and the system worked flawlessly until a couple of days ago.

No warning (NO GEN LIGHT ILLUMINATION), the battery (NEW) went dead while driving down I$ to Orlando.

OK, it's not charging again BUT, no gen light illumination either !!!

I pulled the gauge out of the dash and pulled the gen bulb.
The buld tested AOK with 12v, it lit right up.

The gen light does not illuminate when the ignition is turned to the "on" position either.
Is the gen light supposed to illuminate when the idnition is on, engine not running???
There is comparable voltage on both bulb terminals with the ignition on.

Still, the charging system tests that Thorensen provides does not provide any results when either supplying 12v to terminal DF OR when shorting terminals DF & D+.

These tests are based on what operation will make the gen light go out BUT, both tests were done while checking battery voltage and nothing makes any increase in battery voltage (12.06).

I cannot condem either the alternator or the regulator without positive test results.

ANY IDEAS ???

[paslantnose]

Maybe I can simplify the problem description here.

Charging system is not functioning BUT, the "gen" light is NOT illuminated ????

[paslantnose]

Ok then, i'm at the mercy of the local alternator shop.
It's got me by the short hairs this time.

[Early_S_Man]

The warning lamp must work for the field windings to get their pre-excitation current.

Could be a loose or corroded connection at the warning lamp holder, corroded/oxidized lamp holder, corroded connection at terminal #11 of the 14-pin connector, fractured Blue wire under the insulation, or loose/corroded Faston connector at the brush holder of the alternator. Clean all of the above connections and see if that helps.

My suggestion, if the above doesn't work, is to run another wire outside the car from warning lamp to the engine side of 14-pin connector ... if the warning lamp comes on with ignition switch on, the you know the problem is between dash and 14-pin connector. If you have to run the 'new' Blue wire all the way to the brush holder D+ Faston tab to get the warning lamp to work, then the break in the wire is in the engine harness.

[paslantnose]

Warren, thanks for the reply and MERRY CHRISTMAS !!!

The bulb socket and socket terminals are all clean.
I pulled the wires off the bulb socket and checked each with a voltmeter, they both gave near equal readings (battery voltage).

One side of the socket has the red ignition wire, the other side has the blue wire and a green w/blue strip wire ? I'm not sure what the green w/blue stripe wire is for.

Your thought on the blue wire having an open sounds like good advice and that will be my first objective tomorrow.

Thank you again sir, much appreciated !

[paslantnose]

Back on this to thank Warren for his suggestion.
We ended up tracing the blue wire all the way to the alternator this morning (yep, opened the presents then out to work on the p-car !).

Along the way, we kept getting .68 volts on the blue wire until we pulled the alternator and had a look.

Close inspection (yellow arrow) revealed that the wire inside the alternator was burned to a crisp.
It's quite evident that the insulator block for this terminal is positioned wrong, allowing the inside wire end terminal to rest nicely against the alternator case (red arrow).

We went a step further and checked the blue wire from the alternator all the way to the gen light for short to ground and came up negative.

The rebuilder is only 20 miles away and will be seeing me in the morning for a replacment.
I'm just glad it didn't fry any of the car's harness !
Hopefully, the regulator didn't suffer any damage.

THANKS WARREN !!!

[paslantnose]