85 grand marquis - electrical problem

[aray4al]

the amp light comes on when car is started and stays on. battery does not charge. car will run until battery dies. where/how do i solve problem. have tries various things over time and feel i am running in circles with this. my cup is now empty.

[way2old]

What have you done so far? Sounds like the alternator or regulator is bad. Look at the wiring going to the regulator to be sure the wire coating is not gone allowing the wires to touch.

[aray4al]

am wanting to start from scratch with an empty cup (so to speak). problem may be simple, but feel have been chasing my tail with this. i appreciate you helping me.

have replaced alternator and voltage regulator.

appears to be short in wiring that not allowing battery to charge. i connect test light from battery to cable and light comes on. pulled fuses and light goes out when lighting circuit fuse is pulled. haven't found short yet.

going to start from square one today. are these steps in right order.
1st step-battery and cables. 2nd-step alternator and wiring to/from. 3rd step-voltage regulator. 4th step-would be to check for short in wiring.

[miamibob]

Two bits of advice that should help. Firstly, listen to WHATEVER WAYTOOLD says as he has a great deal of experience and REALLY knows what he is doing (besides, he is my friend). Secondly, check the connectors that go directly into the alternator and change them if you are not sure. If everything else checks out (for certain) these have been known to be bad and most folks never think of them!!! Let us know what you find out.....MB

[way2old]

Here is a little info on the light and charging.

The indicator lamp glows when field relay fails to close. When ignition is in the On position, battery current flows through the charge indicator lamp and a parallel resistor, and through regulator to field, and the lamp comes on. Vehicles with electronic voltage regulator have a 500 ohm resistor. On all others the resistor is 15 ohms. When the alternator builds up enough voltage to close the field relay the charge indicator lamp will go out. Place ignition switch in the Run position with the engine stopped. The lamp should light. If not, the bulb is burned out or indicator lamp has an open circuit.On vehicles with electro-mechanical or transistorized regulators, an open resistor wire in the alternator charging circuit will usually cause the indicator lamp to remain on until engine speed is increased to approximately 2000 RPM. In some cases the lamp will remain on above 2000 RPM. The charge indicator lamp may be tested using a test light containing a No. 67 or 1155 bulb. Disconnect regulator wire connector from regulator, then place ignition switch in the Run position. Place one test lamp lead on regulator wire connector ``I'' terminal and other lead on regulator base. Test lamp will light if circuit is in proper working order. If 15 ohm resistor or circuit is open, indicator lamp will operate at full brightness and test lamp will not light.

Hello MB

[aray4al]

through a hectic sked, i have managed to re-verify wiring from/to alternator in engine compartment. no abrasions noted.
I will have new alternator checked 6/26 to ensure good unit(to be safe).
will follow test instructions on 6/26 also with test lamp.

item of note: if i connect test light from neg batt post to neg cable, test light comes on. if i pull fuse in no. 8 position in fuse box, light goes out.