car is killing batteries, no interior battery dummy light on

[mountaindude]

1984 Tercel 4wd. No interior panel battery light comes on anymore. The car seems to kill batteries quickly, like overnight. I have replaced battery, alternator, voltage regulator, starter. Everything I can think of. I even ensured that interior lights were not left on. Winter is fast approaching and this is my preferred car for the Sierra snow. Any ideas? MD

[rer233]

Are you saying a fully charged battery will go dead if you let the car sit overnight? If so, you've got a current draw somewhere (REAL unusual for our cars.) Easy way to check for a draw is to disconnect one of the battery cables (doesn't matter which one- I usually do the negative one) hook one lead of a test light to the disconnected battery terminal and the other to the disconnected cable. If the light turns on, you have a draw. Then you just disconnect stuff and pull fuses 'till the light goes out to find the problem. I'd start by disconnecting the alternator (is yours internally regulated- if not, disconnect the regulator too.) I'd also suspect any after-market accessories (ie radio, gps, etc.)

Another possibility is a burned-out charging light bulb (that would not cause a draw, but could account for a no-charge condition.)

Good Luck- let us know how it works out.

[4wdEconoBox]

I would probably lean more towards the burned out charging bulb, just because you said that it doesn't come on anymore. If that light gets blown, then your alternator doesn't get "excited" and that means your alternator won't charge the battery at all. Next chance you get, check your battery voltage with the engine off using a digital voltmeter on the terminals of the battery and see what your voltage is. Then start the car and check the battery voltage again, and if the voltage is the same or lower than the 1st number you got then the alternator isn't charging and more than likely its a blown charging bulb. You may have already known how to do all of that already, but I didn't know your wrenching level, so I figured it wouldn't hurt to explain it the most detailed that I could haha. Good luck!

[mountaindude]

Thank you very much. I will give it a try and report back.

[mountaindude]

UPDATE:
I pulled the steering wheel and getting to the bulb was easy. The bulb looked fine. I swapped the seat belt light bulb with it, and it with the seat belt light. The bulb does not appear to be the problem. Charge light still not coming on.

On to looking for a draw.

[rer233]

Draw isn't going to keep the charge light from coming on. Only bad bulb (which you've ruled out) wiring problem, bad alternator, or regulator will cause the light to stay off. Is your regulator internal or external? As stated earlier, you should check the battery voltage with the engine off and running (my guess is you're not charging.)

[mountaindude]

I put an Ohm meter on the battery. The alternator is drawing juice. So was the dome light fuse, but the door was open. It's a new/ rebuilt alternator. It is a replacement. I will change it out and see where that leaves me.

[rer233]

I assume you mean ammeter. If the door is open, it's normal for the dome lamp fuse to show a draw (dome lamps would be on.) My guess is alternator (internally or externally regulated?)

[mountaindude]

I believe external.

[mountaindude]

My 1984 Tercel has a voltage regulator behind the battery where my 1985 does not. Could it be that I have the wrong alternator in my 1984 and the alternator has its own internal regulator causing a conflict with the voltage regulator behind the battery?

[rer233]

Could be- do both cars have the same alternator plug configuration? I've got no experience with external regulator cars- probably had 11 or 12 tercel wagons, ALL internally regulated. Maybe some one here has had ext. regulators??

[Petros]

it is not really possible to install the wrong alternator, both the mount and the connector are different. You would have to really work at it to modify or fabricate a new mount, and cut off the existing connector and install the correct matching one in the wire harness. Seems you would have known if you did that drastic modification to it to make it work.

I have owned several of both, I do not think I have seen any external voltage regulator (at least in North America) after model year '85. From '83-85 you could get either type, but they are not directly interchangeable, bolt up is different, connector is different.

[mountaindude]

Update:
Well I tracked the battery drain down to the dome lights. Pulled the fuse. The car is now fine and winter driving again. Thanks for the help.

[Petros]

Solved the problem for now.

I have seen the contacts become corroded and short out on the dome light fixture. these dome light fixtures are common to all of the Toyota line up from about '82 through perhaps 1990, I have seen them in corollas, trucks, camrys, etc. so you can find a good one in a wrecking yard, but the color might be slightly different. you can also remove it easy enough and drill out the rivets and clean the contacts, and perhaps solder it back together, I have tried that but have not had success fixing a bad dome light fixture.

[mountaindude]

Solved the problem for now.

I have seen the contacts become corroded and short out on the dome light fixture. these dome light fixtures are common to all of the Toyota line up from about '82 through perhaps 1990, I have seen them in corollas, trucks, camrys, etc. so you can find a good one in a wrecking yard, but the color might be slightly different. you can also remove it easy enough and drill out the rivets and clean the contacts, and perhaps solder it back together, I have tried that but have not had success fixing a bad dome light fixture.

I never used the dome light anyway. So no big.