Topic: Elantra stops running, drains battery while driving

[nkoper]

Hi, I wondered if someone could suggest what might be going wrong here. We've had the vehicle in the shop but they couldn't find the source of the problem.

We were driving our 1996 (?) Hyundai Elantra stationwagon the other day and all of a sudden the radio and interior lights stopped working. About 15 seconds later the engine cut out.  The only thing the shop could find was that the battery was completely dead. They checked for shorts, etc., and did a full diagnostic but couldn't find anything. The battery was new last year and holds a charge.

Any suggestions for what might be going on would be great.
Thanks.

[tenpenny]

Obviously, the engine was running on battery power only....the alternator must be dead.

[RayT]

I'd think the alternator too. I had a similar problem.

[Railton]

I had that probelm once and it was a "fuseable link".
Railton

[barrie1]

Make sure your Fan Belts are tight as if not they can not produce enough power to run the car correctly.

[weebl]

My dad had that happen - it was an alternator problem.  I'd say check into the alternator and belts first, then move on to the fuseable links and other potential causes.

[articsteve]

Confused.  Are you still driving it?  Or is it sitting somewhere with a dead battery.

You need to get a cheapo digital multi meter. Run car and place leads across battery.  You will want to see about 14.3 volts. 14 will do.  If you don't, go inside car and take another reading from the cigarette lighter or the fuse box for that matter.

If it is higher than the battery then yes I would look at the fuseable links.  If the voltage is the same all over the car as the battery and it is 14 volts more or less I would say it's the battery.

However, after the car is off and the battery having a good charge, the meter will tell you if you have a rogue voltage drain.

You can wire the meter to the cigarette lighter  so you can drive around and keep an eye on the charging rate or a voltage loss over a period of non use.  

You aren't going to get to far on this without a digital meter.

(Message edited by Articsteve on April 18, 2005)

[duck]

Sounds  like any HYUNDAI product.   "Alternator."


Hyundai Dealers can't even find their azz much less a dead alternator.

[nkoper]

Thanks for the advice... not sure it's the alternator though, as the shop specifically checked it and said it was fine.

[barrie1]

If the Fan Belt isen't tight enough then the alternator can not produce enough hydro to run the vehicle and all its appliances so the Battery takes the hit on power.

[seaking]

I've been chasing this problem for a week or more.  I have already changed the alternator to no effect.  Where is the fusible link?

[Railton]

Seaking, Under the hood, usually in a black box with a snap open lid. Check the owners manual for the location. They look kind'a like big relays.
Railton

[articsteve]

I have already changed the alternator to no effect

Lets start at the beginning.  Why did you change the alternator and did you do that yourself?

What year, model and mileage?

[seaking]

98 Elantra - 145K.  Vehicle died in the Canadian Tire parking lot.  No charging light ever came on, but it is like the description above - lost all 12V systems one by one, then the engine.

I suspected the alternator myself, but since it was dead at Cdn Tire, I let them do a diagnostic rather than being towed to the dealer.  They confirmed the alternator, but wanted $700 to change it.  I bought a rebuilt unit and changed it myself.  (Unfortunately, I had to give my old one as a core, and it appears there was nothing wrong with it.  Should have bench-tested it.)

After the change, the problem persisted.  Chasing it around with a multimeter, we found that the alternator would charge intermittently.  It would sail along at 14.5V for 2-3 minutes, then quit, then it might or might not pick up again later.  

Interestingly, the battery light on the dash will either work or not together with the alternator.  If it's in a charging mood, that light will turn on at startup.  If not, no light.  The failure to charge seems to take the indicator light with it.

We are now chasing the problem along one of the two wires off the regulator - the one that governs the idiot light.  Apparently, the behaviour of the circuit is that voltage on this wire governs the regulator's ability to charge or not charge.  (I am paraphrasing here - my dad is the electrical engineer - not me.) When the battery reaches the desired voltage, the circuit switches off.  If you lose a connection at this wire once that circuit is off, the regulator is unable to resume sending power to the battery.

The problem is likely not in the fusible link.  It is somewhere in that wire.  We need to chase it through the harness.

I suspect the battery is now damaged as well.

[articsteve]

So you don't have a slow drain somewhere but rather an intermittent interruption in juice from the alternator.  Yes, I would agree with you that you have a corroded wire or bad connection.  I have had this once on a 302 Ford.  About 2 feet off the alternator inside that usual plastic wrap tubing.  Just substandard Ford wiring is all it was.

Test light did the trick. Although, on this occasion the charging light stayed on until it was fixed because the bad wire had gone to a complete open. In your case an intermittent will be more difficult because it probably will come and go as the car bumps along the roadway.

[seaking]

The wire seems to come and go with the engine just at idle.  I'm wondering whether heat is playing into it.  It works best with a cold engine.

Interesting to note that the daytime running lights are also associated with this wire, and I've had an intermittent fault with them for years.

The unfortunate thing is that the battery will not hold much of a charge anymore, so I can't even get away with putting it on a trickle-charger and using it for short trips.  It's dead again within 40 km.  Either being drained as it was or the way it was recharged at Cdn Tire seems to have crippled it.

Thank goodness for the Corvair!  It's now our prime vehicle....

[articsteve]

When Canadian Tire puts weak batteries on the quick charge (60amps) it can kill the plates.

I'd pull the fuse on the daytime running lites and see what that does for you.

[seaking]

Should post the eventual fix:  As it turns out, we traced that short all the way back - into the brand new alternator.  Cost us the better part of two weeks because we never considered the possibility that the new alternator was just as bad as the old one.  After installing yet another alternator, all is well.

The problem was as we described it, though the fault was in the regulator itself.  When warm, a circuit in the regulator (which is housed inside the alternator housing) opens up, preventing both a charge and the warning light from operating.  The alternator probably would survive a bench test, as it would likely not generate enough heat to cause a real problem.  It wouldn't show up until installed in an engine.

[Roadrunner]

Seaking, thanks for posting the final result with a good explanation. This way we ALL can benefit.

[articsteve]

You may have fried the regulator when you installed the first reman unit from Crappy Tire.  You kept saying your battery was really weak and not holding a charge.  Installing a new alternator on a very discharged battery can wreck them fast.