'95 Cavalier problems with cold weather

This one has stumped a couple local mechanics. I have a '95 Chevrolet Cavalier, and it has problems in cold weather. Symptoms are:

  1. Car starts up fine, but then everything electrical runs poorly: dim headlights, turn signals won’t flash, heater will hardly blow, ABS warning light on, wipers are lethargic, etc.
  2. Continues that way for anywhere from 45 seconds to about 5 to 10 minutes.
  3. Then all of a sudden, in the blink of an eye, everything starts running just fine, and no hint of any problem until the next time the car gets too cold.

The temperature threshold seems to be around 15 to 20 degrees; above that and no hint of a problem; below, and this happens all the time. ONE time, at a temperature of about 0 degrees, this condition lasted long enough that the car finally failed much like you’d expect to see with an alternator failure (it was being driven and had been running about 15 minutes by that time)… and even in warmer weather the following day, the battery was still dead and car had to be jump started, so this is draining the battery during that initial period.

Mechanic has tested the battery and alternator and said both are fine, though they obviously weren’t tested in extreme cold weather conditions. Several people have tried to tell me it must be an intermittent short and I’m just imagining the connection to cold weather… but it’s been a completely reliable correlation all of last winter, and so far this winter, too. Since this has been repeatedly asked of me, when things start working, it’s not because of hitting a bump. I often have just left the car running in park, and it will eventually reach that point and run fine.

Any ideas?

How old is the battery? When things start running fine, has the car warmed up?

The battery is probably quite old… 6 or 7 years? I cannot find a date on it. It did test good though.

When things kick in, the car is undoubtedly a little warmer since it’s been running, but I don’t know how to get a number. It’s not always warm enough to even register on the dashboard temp indicator (but sometimes in very cold weather it warms up all the way to the normal range on that indicator before kicking in). Occasionally it only takes to the end of the block, so in that case it can’t have warmed up too much.

Just to cover a remote possibility, clean the two ground connections at the bell housing.

I am thinking that the “exciter” in your alternator has gone bad. I don’t recall the technical name, but basically when you first start the car the alternator is freewheeling, after which an electrical pulse should “excite” it (activate it) and it starts to charge the car. I have a feeling this is not happening on your car due to temp, and while the alternator might work find after its “excited” it has a bit of morning sickness when cold. I am not one to just throw parts at a problem but I used/new alternator for that car is cheap and should solve your problem. UNLESS the wire/trigger that does the “exciting” is bad…

Whack the alternator.
No really.
Whack the alternator.
Get a piece of 2x4.
Put it on top of the alternator.
Whack it with a hammer.
You may find you can get the thing to kick on almost instantly - and not have to wait 10+ minutes.

If you have stuck brushes or a bad electrical connection somewhere - this will show it.
I dont think its the excitor as much as its the brushes not getting power to the stator/rotor.

Electrical motors spin - but you have to make an electrical connection. This is done with brushes. They wear out.

Get a new alternator - or better yet pay a visit to a local scrap place and get one for 50$. Heck get 2 for 100$. That way when the next one dies in 4-10 years, you can take all 3 alternators, and with just a little luck, you should be able to get a good set of brushes, a good stator, a good rotor, a good voltage regulator between the 3.

but do get a new alternator. This issue will start happening when you are driving around (battery light will come on - and then randomly turn off but eventually stay on until the car dies)

Did those mechanics clean the battery terminals, on both ends on both battery and body/starter/alternator?
I’d look there first.

I am with RemcoW 100% This is hugely important. Dont ignore the grounds either. Clean and grease and tighten all your electrical cons…

The guy telling you to whack your alternator is trying to free up a stuck brush…and if your brushes are that small and getting stuck the Alt needs a rebuild and new brushes…or buy a new one.

Remco, thanks, the second mechanic did indeed check a lot of connections and clean a lot of corrosion from battery terminals, though he told me it was almost certainly not causing the problem. I guess I’ll wait for the next cold front, and either rejoice, or get back to looking!

This is a classic symptom of a bad ground connection, and I had the exact same problem with my POS Volvo, many years ago. It would only manifest itself in very cold conditions, but when it happened, all of the lights and electrical accessories would function very weakly. As soon as the engine reached full operating temperature, it was like throwing a switch, and suddenly everything electrical would return to normal.

The problem will be locating the bad ground, however. I would suggest taking the car to the best auto electrical specialist in your area, and leaving it overnight so that they can do the proper testing in the early AM, when it is really cold.