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[icon] My st00pid car, round two - Patti
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Subject:My st00pid car, round two
Time:09:02 pm
My car is failing to start again. Here's what I know about the problem:
  1. Saturday afternoon, I left the lights on for about three hours and killed the battery.
  2. I jump-started the car and it ran fine. Drove it about 45 minutes, parked it, drove it home several hours later. All fine.
  3. Sunday afternoon I drove it to work (about 15 min) and back a few hours later. Fine.
  4. Monday morning it wouldn't start. I jump-started it, drove it to work, parked it in the garage, and jump-started it again to get home.
  5. Today I repeated the Monday ritual.


    And that's the sequence of events. Here are additional details.

  6. The battery is less than a year old.
  7. The won't-start symptom is unusual: as soon as I turn the key to the "on" position, all the dash lights cut out. I don't even have to engage the starter.
  8. The battery has been reading about 12.9V, and I've checked it several times. (Seems normal.)
  9. When the engine is running, I'm getting around 14.5V. (Seems normal.)
  10. This evening, largely in the interest of paranoia, I put a battery charger on it. It deemed the battery fully charged in less than five minutes.
  11. Today when I was driving either to or from work, the radio would cut out for a second whenever I hit the brakes. Other functions seemed completely OK.
  12. Tonight when I tried to start it after charging the battery it had the same dead-on-"on" symptom. I also heard weird noises from the rear of the car, like something spinning up, and then like a motor of some sort getting caught in a cycle. In the interest of science, I left the key in the on position for several seconds. After a while (maybe 15-30 seconds?), the dash lights slowly came up. Once they did, the car started normally.
  13. The car is a convertible, and it has a CD changer in the trunk. The power antenna was forcibly removed a couple of years ago, though the strange sound was somewhat similar to what I would expect from a power antenna cycling up-down.
  14. Somewhere in the process of investigating the weird noise, I flipped the switch on the convertible top to put it into manual mode in case the motors or wiring were getting wet and shorting out. Immediately after I did this the car still was in dashboard-blackout mode, but I finally managed to start it shortly thereafter.
  15. The car has shown the not-starting behavior after being out in the rain, and also after being parked in a dry garage for 10+ hours. However, it's been raining heavily for the last couple of days.

Writing this makes another experiment obvious-- get into the car then try to start it without touching the brakes, and then try to do the same thing with my foot on the brake.

So what I think I know at this point is: that the battery is OK, the charging system is OK. Something in the car, possibly related to the convertible top but more likely related to the brake system, is shorting out. This may or may not be related to rain. Killing the battery on Saturday was probably an unrelated coincidence.

Anybody want to shoot holes in my assumptions, or suggest alternate theories or experiments?
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(Deleted comment)

whipartist
Link:(Link)
Time:2009-03-04 07:34 am (UTC)
What makes you suspect those?
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(Deleted comment)

whipartist
Link:(Link)
Time:2009-03-04 07:47 am (UTC)
I did, a couple of years ago. It's in a landfill somewhere, I'd imagine.
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adb_foldem
Link:(Link)
Time:2009-03-04 07:42 am (UTC)
The sound from the rear is almost certainly the antenna mechanism. Can't help with the rest of it.
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whipartist
Link:(Link)
Time:2009-03-04 07:48 am (UTC)
The power antenna and motor got pulled out a couple of years ago.
(Reply) (Parent) (Thread)


stevecohen
Link:(Link)
Time:2009-03-04 03:11 pm (UTC)
Might the sound from the rear be the tank-mounted fuel pump? Most modern cars have them for one reason or another.

Is it possible that one of the batter terminals is not clamped tightly? I have had similar problems when a battery was replaced and one of the terminals was barely making contact. You might try disconnecting them both, cleaning the terminal and the post, applying the appropriate schmutz, and putting them back together.

If it is not the battery terminal, start looking at the upstream wiring. Ground strap? Positive lead?

Before an accessory could short things out badly enough to blacken the dash the fuse for said item would long since be vapor.


(Reply) (Thread)


greeklady
Link:(Link)
Time:2009-03-04 04:43 pm (UTC)
OK this is my two cents worth. I am not a mechanic, nor play one on TV but was a rat in the garage and under the car when my dad worked on them. SO worth a shot to look at.

The fact that when you hit your breaks you are losing juice elsewhere does scream of electrical problems. That being said, makes me wonder about your alternator working properly. There should be no juice issue while the car is running.

You can find an electrical schematic on line and get someone with electrical engineering background to get their fluke and test it. My hubbie did that for an old Peugeot I had. We fixed half the shorts but then ended up getting rid of the car.
(Reply) (Thread)


allknight
Link:(Link)
Time:2009-03-04 04:46 pm (UTC)
Patti,

Interesting problem/s here, I like the idea it might be related to some rear electrical fuel pump. But I also wonder if your wiring in the rear of the car going to brake lights and potentially a fuel pump might be shorting out too.

I had an old car that had previously had some sort of engine compartment fire before I bought the car. So when it go hot it wouldn't start. I thought it was the starter and I replaced it several times all to no avail. Later on I was told by a mechanic I trusted that the wiring harness had been spliced several times and needed to be completely rewired. As each splice would suck juice out of the system especially in hot conditions. Good luck keep us posted!
(Reply) (Thread)


silveredboy
Link:(Link)
Time:2009-03-04 08:35 pm (UTC)
This may sound totally ridiculous since I don't know what kind of car you drive. But has it ever been wired for lights for a trailer? If so, I'd look at those connections. Have you been under the car and looked at wires that run to your brake lights?
(Reply) (Thread)


evwhore
Link:(Link)
Time:2009-03-04 09:32 pm (UTC)
Put the top down and fill the interior with marshmallows.

This won't prove anything, but it will look cool. Take pictures of people diving in.
(Reply) (Thread)

(Deleted comment)

whipartist
Link:(Link)
Time:2009-03-04 11:55 pm (UTC)
I think the alternator is OK. Otherwise, I probably wouldn't be getting 14.5V across the battery when the engine is running. It also seems like doing other electrical-intensive things, like turning the wipers or the fan on, would make the radio cut out too. They don't.

My guess is a short in the brake light wiring.
(Reply) (Parent) (Thread)


whitebird
Link:(Link)
Time:2009-03-05 04:30 am (UTC)
Is it possible that the connector for the missing power antenna is getting wet and shorting itself out? And then slowly drying out over time?
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[icon] My st00pid car, round two - Patti
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