Charge and Brake light on

[Logbear]

After having such good luck working on my "86" with the blown 60 AMP fuse, I thought that when my son called with the charge and brake light on, I would be able to solve it pretty easy. I even have a post from a couple years ago dealing with the problem. I figured it was the voltage regulator, ordered one for him to be delivered in Ellensburg, and walked him through how to unplug the old one and plug in the new one. That was easy. Or so I thought. But the lights stayed on. I had him drive the car to Orielys and they said his alternator was no good. I had a couple of spares here at home that I had tested that were good, so I drove over yesterday to swap alternators. It turns out that the alternators I had were slightly different. The three prong plug on his is like a perfect "T". The two I had have a slightly offset "T". So they didn't work. I took his alternator down and had it tested. It tested fine. I came back to his place, put it back in and voila, the lights were off. To celebrate, we went for dinner. When we finished dinner we went our separate ways, but my son called me right away and told me the lights were back on again. I turned around and checked it with a voltmeter. No charge. I removed the alternator, took it to Orielys and this time it tested bad.

All I can figure is that the alternator went bad, then was good for one test and a quick drive, and then went bad again. Does this make any sense?

Anyway I got a new alternator and I'm heading over tomorrow to see if that will fix it. I'll report back with the results.

There was one other thing that I found. A wire going to a single wire green plug was almost completely broken. It was hanging by one strand of wire. Touching it and bending it finished it off, I stripped the wire, took a little jumper wire with clips and made the connection. I thought this might be the problem but the charge and brake light were still on. The car ran but when I disconnected that wire the engine died instantly. I have since made a good connection with an old plug I had.

[Petros]

there are two types of alternators used on the '83-84 model years, some have the internal voltage regulator, and some have the external voltage regulator. the connectors and the wire bundle is different. there does not seem to be any reason for which production date got which alternator, you have to inspect it to know which alternator it has. It seems that all of the alternators used on the 85' and later are internal voltage regulator, however, those types use a different mount and connector than earlier models. So among the whole production run there are at least 3 types of alternators used and are not interchangeable unless you change your connector, wire bundle and the mount.

Sometimes alternators can work intermittently, depending on what failed. Fortunately a new replacement alternator lasts a very long time, like 200k miles or more, so you do not have to replace them very often.

[irowiki]

Apparently the internal regulator was considered "cold weather" spec, higher output maybe?

[Logbear]

Well that was simple. A new alternator and the car is fine now.

[Sunburst96]

So on this classic charge\brake lamp issue, recently put in new speakers and went a whole day until my indicators came on, no big deal. Drove around until my car died(bad alternator) so i went through the usual diagnostics and found the almost bad alternator. I had been smacking the alt with a wrench to keep the brushes moving(not the best approach I know) but this helped until it sparked one night when wrenching it and blew the AM 60A fuse. Replaced both alt and fuse, the charge lamp relay and other fuses are all good. Indicators are still on but brighter, wipers wont move fast at all, and heater fan barely blows. Will check with volt meter today, but need some help on this one.

[irowiki]

Western slope! The family is in Montrose and I'm down south of Durango in Farmington NM.

That means either the new alternator is bad, or your battery is bad too.

Or you may have blown a fusable link! I would check the battery first.

[Sunburst96]

No way, stoked to know your close by!
Right now I'm leaning towards a bad battery, car died in town and I had to have some guys push me. She fired over and drove home, waiting for the volt meter now.

[Petros]

if the light is still on likely the battery is okay, check you are charging. easy fast test (if there is enough power in the battery to start it), turn head lights on and check brightness (against a wall is good, or look directly into them), than start car and check lights again. if charging they will be noticeably brighter. if no change, it is not charging.

check output, also check if you have separate relay that it is working (simple test, see FSM). often rebuilt alternators are bad right out of the box, so do not be surprised if that is the problem. but do not assume that, check the system over to make sure.

I once drove cross county when the battery blew a cell on Tercel4wd (battery would only hold nine volts), it ran fine but would not crank to start. No charge light came on. I just always choose to get gasoline where I could roll out of the stall and bump start. when I had a choice of stations I would pick the one with the best down hill run away from the pump island, I would position the car so it would roll on its own and park it. Than fuel up and pay, as I get in I would give it a shove and hopped in. Once rolling I would put in 2nd gear, ignition on! and let out the clutch and drove way. I do not think any one would have even noticed I got so good at being very casual about it. Point is the charge light was off and it ran fine, it was the battery that would not hold a charge so it would not start the engine. I thought the cables were bad, but once I got home and spent some time cleaning contacts, etc and testing the various components with volt-olm meter. when the batter only showed nine volts with engine off, I took the caps off and tested voltage across each cell (you carefully put the probs down into the fluid without touching anything else), one was completely dead.

[Sunburst96]

Battery is definitely good, read the spec sheet that came with the alt, output is 12.5 volts this is also what it read when I had the volt meter on with car running. Guessing this would cause the slight lack of power and the lights being on?... Honestly not surprised, going to Napa tomorrow morning. But will check my relays to be safe. Haha, only in a Tercel, we sure are persistent with our lovely cars aren't we!

[Petros]

A fully charged battery should show 13.2 volts. If you are only putting out 12.5 volts it will not charge, it has to show about 14v for it to charge. Sounds like something in the system is still bad. Take the new alternator in with you, they can bench test it to verify it is good. Along with the external relay if your car is so equiped. BTW, if you have an external relay system you can not use the internal relay alternator. So veruy you have the right one. The connections are different.

[Sunburst96]

I have the internal regulator for sure and got the right one, made sure prior to the purchase. Will bench test tomorrow at crapa.