90 GL Electrical Woes Plz Help!!!!

[IADrivewayMechanic]

Hello, I need some help. I have a 1990 Taurus GL Auto. A/C 3.0 V-6. The battery light came on recently, I checked voltage 11.2 volts! Ok alternator was original so I replaced it along with the external voltage regulator from Napa. So now the alternator charges and the battery light is off, but there is something draining the battery. I took an amperage reading between the negative battery terminal and the negative cable(4.5 amps). Then if I unhook the alternator field winding the amp draw goes to 0.17 amps. I had Napa check the alternator on their machine and it passed. So, I'm confused do you think I have a problem with my charging circuit or do you think it is a shorted ash tray light or something like that?

[shorod]

Welcome to the forum, and greetings fellow Iowan!

Hmm, that does make the alternator seem suspicious, but just to be sure, you may want to isolate some other circuits in the car with the alternator field winding connected.

Basically, you should be able to remove fuses one at a time while monitoring the current draw. If you find a fuse that causes the draw to decrease significantly, then focus on that circuit. If you find that the glovebox, trunk, or hood lights are on that circuit, then those may be a good place to start.

The ash tray light should only come on with the parking and headlights.

-Rod

[IADrivewayMechanic]

Hi Shorod, I will double check the other circuits in the morning (I have checked so many things ). The ash tray is suspect, it was always on when you pull it out of the dash, I unhooked it tonight and nothing changed but I will have to unhook the fuse and see if that does anything. Thank you for your response, this problem is driving me !!!!!

[IADrivewayMechanic]

UPDATE:

Well, so far I have found a short in the circuit that feeds the interior lights and trunk lights. I have also found the Charge Indicator Light circuit has continuity to ground (11 ohms red/light green wire from instrument cluster to ignition switch). Today I fixed the interior light circuit, tomorrow I'll have to track down the short in the charge indicator light.

[shorod]

Try removing the charge indicator bulb, then measure the resistance to ground. The 11 ohms resistance you are seeing may be the resistance to ground through the bulb.

-Rod

[IADrivewayMechanic]

Ok, I may be confused. I bought a haynes automotive electrical book and it says the indicator light is in parallel with a 510 ohm resistor which when the car is not charging allows the light a ground. But when the alt. charges voltage is applied on the "negative" lead of the indicator light causing it to turn off. My wiring diagram shows the path of current like this... Pos. Bat. terminal to starter solenoid to ignition switch to charge indicator light to voltage regulator to alternator. So I'm thinking I should'nt have a ground between the indicator light and the ignition switch, right???

[shorod]

Where are you placing your meter probes when measuring a ground between the indicator light and ign switch? If you have the meter set to "resistance" or "ohms" and have one probe on ground and the other probe on the charge indicator terminal that is tied to the ignition switch, but the bulb and voltage regulator are still in circuit, you may be measuring a sneak path to ground. If you remove the bulb and/or voltage regulator and measure something significantly smaller than 510 ohms to ground, then I'd agree that you have a problem in the wiring somewhere.

With the bulb and regulator in circuit though, I'd be hesitant to conclude you have a short to ground. Pull the bulb and check for resistance to ground on both bulb terminals.

-Rod

[IADrivewayMechanic]

I have found multiple problems. The interior light circuit was shorted to ground at the sunshade light and at the dome light. I also had a intermittent short (.01 ohm) on the red/light green wire goes between instrument cluster and ignition switch.

So now I do not have a battery draw with the car off, but when the car is running the charge light stays on and only 12.3v at the battery terminals. Today I going to buy another voltage regulator, because I'm guessing all those shorts may have damaged the other one.

I hope this gets it...thank you for your continuing help shorod