See if 12V on red wire to alt. If no check fuse 1D pass side right kick panel. If it is good then PCM right behind fuse is not sending exciter volt to regulator in alt.
ATLAS AUTO ELECTRIC LLC.
October, 14, 2012 AT 8:33 PM
ON 94 & 95 Buick LeSabre. The Charging System, is simple. First - check battery voltage with key off. Should be +12.6 volts. (NO-LOWER than +11.0!) If battery is low take it to Autozone and get a FREE charge. Now with key off, read +12.6 to +13 volts, on battery Plus+ post and on the large Black wire going from the Plus+ of battery to the screw-on terminal at the back of the ALTERNATOR. It should have +12.6 there also. If not, check black wire for bad contacts and dirty conections. If Okay. Start the car and check battery for +13.5 to +15.0 volts while car is running. If battery voltage reads +12.5 or Lower it is NOT-Charging. Stop Engine and remove key.
Now, with a volt meter set for ohms. Put the black meter lead on the -NEG. Post of battery and the Red meter lead on the outer Medal case of the Alternator. It should read very LOW-OHMS 0.05 or less!
If it reads higher then 0.05 (0.6 0.07 0.08 & up, ) you have a BAD or poor ground. Clean, Brush & tighten all ground wires and cables. The -NEG battery ground cable goes to the engine block large bolt under the lower right side of the Alternator. Also clean & brush the small wire from Neg of battery to the grounding screw on the passenger front fender. Restart car, check battery voltage again, should be +13.5 to +15 volts. If YES Good for YOU! If voltage is still +12.5 or lower, Check the small red wire the goes to the side plug of the Alternator for +10 to +12 volts when car is running. If it has correct voltage, the Regulator inside Alternator is bad.
If the voltage (O volts, check 1D fuse, if fuse is good or voltage Under +8 volts or Low to high Intermittent volts)*** The ECM/PCM has a internal problem and needs replcment. DO-NOT-BUY ONE FROM THE GM - DEALER! WHY? (*WAY-OVER-PRICED-GM-DEALER-PARTS*) call 3 or 4 WRECKING Yards and buy a used (Delco) unit for about: $75.00 to $100.00. Do-Not give them your old unit keep it because you will need it to swap the eprom from yours, into the new one. (Easy to do.) The 1994 & 1995 BUICK 3.8 ENGINE GENERAL MOTORS (ECM/PCM BRAIN-BOX) FACTORY NUMBER IS: 16183247. *ONLY BUY THAT GM NUMBER! NOT-ANY-OTHER. DON'T LET ANYONE SELL YOU ANYTHING EXCEPT A: G.M. DELCO - 16183247! GOOD LUCK!