I check the voltmeter (on the tachometer) before starting my car. Normally it's around 13 V. This morning it was around 12 V. (Actually I think over the past couple days it may have been dropping a bit but at this point I'm not sure.)

I was almost to the train station (5.5 miles from home) and noticed my turn signal wasn't ticking. When I parked I turned on the hazards (no blinking) and have a look under the dash. Then they started clicking/blinking. I assume I have to look at it later and probably replace the flasher.

After work (9 hours later) I got in and the meter read near 11 V. Hmm. I figure I will keep the RPMs higher than normal on the way home. (I often drive at 2500-3000rmp. lower rpm, lower gas consumption.)

Part way home I stop at a red light. My turn signal is on and I notice that the tachometer drops (and goes back up again) a hundred RMP or so with each click. Hmm odd.

This traffic light takes about 2-3 minutes to turn green and then 3 cars can get through so I'm lucky that I'm the first car to get to go. When the light changes I go to take off and the car dies. It doesn't feel like I stalled it.

I tried to start the car and I can't hear the starter. I take the key out and put it back in. The volt meter isn't moving at all. (At this point I swore.)

The kind kids in the car behind me gave me a boost and left. I had to back up away from the curb (where we pushed the car) so I missed that light. As I'm sitting there the car died. *sigh* okay push the car out of the way again.

A friend came down and gave me a boost. We were talking about it and measuring voltages. After about 2 minutes of my car idling with the jumper cables off my car died again. So we let his car idle and charge my battery for 10 minutes. After that it ran well enough for me to get home.

The car is a '79. Based on the connector on the back the alternator is newer and says "IC built-in" so I believe it has an internal voltage regulator.

I think the wiring is still using the external voltage regulator on the left fender. In theory I don't think two regulators should be a problem unless one of them doesn't work of course and with two of them there are twice as many to go wrong.

Voltages measured today from battery negative to positive post while the car wouldn't start:
With key out: 11V
With key set to "on" but not trying to start it: 5V

The voltages measured today while the car was idling are:
From battery negative post to 'B' terminal on alternator : 18-19V
From battery negative post to battery positive post: 7V

After driving home the battery still measured 7V (with the engine idling).

Update: I reved the engine up to about 4000 rmp and didn't see the voltage on the battery move at all.

I have a 12V/2A charge on it right now. I think I'll be taking the bus in the morning anyway.

Canadian Tire's computer brings up a round flasher unit with two terminals. The square shaped one I see under the dash has three. (I think that's the flasher unit. I'm going based on the plastic connector shape and wiring diagram in the Haynes book.)

I'm thinking:
1) Test the external regulator.
2) Replace the flasher unit.
3) Look for bad connections under the dash.
4) Remove the external regulator completely. (I saw some other threads about this.)

I'm worried about letting 19 V onto the battery though. Maybe that's just potential voltage and it would drop with the battery load on it.

Any suggestions for what needs to be done or checked?

Thanks.

 

sounds like something + is grounding, will it hold a charge when its just sitting? also try swapping the battery from another car and see what happens.

i have a similar problem in my GS, but it still manages to get up and go aslong as im above 8V haha. there is a voltage regulator but i have no clue how to adjust it. prolly easier just to replace

 

I checked all of the fuses. None were blown.

I tried pulling fuses one at a time and there were three I didn't try (10, 9 and, 7 whatever those are, 10 is ignition). My friend showed up before I checked the last three. (8 is signal lights so I tried it first.)

The voltage on the battery dropped just the same for all of the fuses when I turned the key to "on".

 

Something is really messed up. The first part sounds like a dead alternator (running only off battery). However, the difference between the voltage at the B terminal and the battery is a problem. They should be the same. This tells me that the alt is trying to charge the battery, but can't. Check the fusible links. Make sure that the alt output wire is connected good (at the fusible links and the alt). Maybe just run a wire from the alt output directly to the battery + and see if that takes care of the problem.

The high output voltage of the alt is because the voltage regulator is seeing a low voltage (like 7v). The alt is cranking up its outpuit to the max to try to charge the battery back up. However, the current is not making it to the battery (seen by the voltage differences measured). This wil create a high output voltage. Also a bad regulator can cause a high voltage as well. However, the battery is not seeing it, so there is a wiring issue somewhere.

Kent

 

Could be that the external voltage regulator is toast, and not letting any current through to the battery. Otherwise, it might be worthwhile to pull the alternator and take it down to Autozone or someone similar that performs free testing, just to make sure it's good...

Hopefully its just something simple..Good luck!

 

I just checked the fusible links (there's only 3 right?). Each one measured well under 1 ohm. (My meter barely moved.) The connectors do look kind of dirty though. It might be a good idea to replace the links and/or scrub all the contacts.

With the car off and the charger disconnected I measured the battery post-to-post at 12V. From the battery negative to the alternator 'B' measured just under 10V.

I was looking around at the wiring trying to figure it out. There are two things (relays I think) connected to the 'B' post via some wires. It looks like the "relays" are also connected to the fan. I'm not sure why there are two. I think the fan may have two speeds.

Anyway each of these "relays" has a fuse along the wire to the alternator. (Fuses are labled "30") Okay so I check the fuses. One fuse looks good. The second fuse is burnt.

I figure I will swap the bad fuse out with the good one and check from the battery to 'B' again. As I went to pull out the good fuse it came apart in my hand. The plastic is brittle and just broke.

I pulled the broken fuse out with plyers and then did the only sane thing I could think of. I put the battery on the trickle charger and came inside to go to bed.

 

I was out of town all weekend and was finally able to look at the car tonight.

The battery was charged out of the car. I got some new 30A fuses for the electric fan. I hooked up the battery and started measuring voltages (with the car off).

Battery negative to positive : 12.5 V
Battery negative to alternator 'B' : 9.5 V

It was dropping 3V somewhere. When the battery was dead and the car was running the alternator was higher than the battery. With the battery charged and the car off the battery is higher. So I figure there is a resistance somewhere in the system.

There is a black wire coming off of the 'B' post. It's wider than most wires on the car but not as wide as a battery post cable. This wire runs to a connector near the voltage regulator.

It looks like the other end of the connector goes downward. I'm guessing to the starter motor. I disconnected the connector and measured 12.5V. This indicated that the single wire to the alternator is dropping 3V. I expect that would take a lot of resistance.

So I measured the resistance of the wire. The connector had oxidized a bit but in the end the wire measured almost zero ohms. Hmm. I got a file and scratched up the connector terminals. Then I re-attached the connector.

Now I'm getting 12.5 V across the battery and from the battery to 'B'. Hmm maybe it's just a dodgy connection. It might be but that doesn't really feel like the whole cause to me.

I started the car and let it idle for about 10 minutes before turning it off. The battery did not seem to drop at all.

While the engine was running the voltage across the battery was a sliver under 14V and from the battery to 'B' was 14.5V. I think that means the voltage regulator in the alternator is working fine.

I didn't try driving the car at all. (It's getting late and I don't want to be stuck somewhere at 1:00 AM.)

I might want to spend an afternoon cleaning contacts all over the car. The car is 26 years old after all.

 

this sounds very similar to my problem, yet my car always starts.

so you think its the voltage regulator or ......... what?

 

I'm not sure. After the battery was charged I didn't see the big voltage drop from the alternator to the battery so I think the regulator might be okay.

I did notice that the electric fan is not spinning when I turn the car on. I thought it used to turn on with the ignition. I see a thermostat on the radiator. Maybe the fan turns on at a temperature and I never noticed the fan moving except when the engine was warm. (I really do think something is wrong with the fan circuit.)

I'm not sure how to test the fan/relays/thermostat but I don't want to drive the car until I'm sure the fan is okay. I'm actually thinking of putting the stock fan back on for a while and seeing if the problem comes back.

 

Your E-fan may be pulling alot of amps. If your negative battery ground is corroding, an E-fan seems to really activate electrical gremlins. May I suggest that you get new battery cables as a first step. If you have an opportunity, you can try a second gen alternator swap; or get one of those third gen alternator kits that has been "stickied" on top of the forum.
In my opinion, the stock SA / FB 55 amp alternator almost poops out if you have an E-Fan, headlights, brake lights, A/C fan and a stereo pulling juice simultaneously. I put a second gen 80 amp alternator on mine, with a new battery ground cable, and had a noticable difference! My gauge registers 13+ volts, now, always whereas it was just at 12 volts when my Black Magic E-fan kicked on.
On the other hand, the stock fan is a great way to go, too.

 

I put the stock fan back on. I couldn't find the shroud screws so the shroud isn't on yet. (I bought screws since then.) I think the engine is running about 10 degrees cooler than it was with the electric fan.

So far I haven't had any electrical problems and the volt meter is is always near 13 when I get in to start the car. The voltage on the battery and the alternator is about 14V when the engine is running.

That said I was not driving the car until yesterday because I had the front wheels off to put on new rotors. Always look at *all* of the new parts before taking the old parts off. I didn't look at the second rotor before pulling the old ones off (and I damaged the bearing seals).

The rotor had a few chips in it. One was 8mm long and almost a millimeter deep. The parts store ordered another set for me but those ones were damaged too. The third set of rotors were good enough to use.

So in the past two days I haven't had any problems.