Odd electrical gremlin. no start, dim dome light (some times) buzzer comes on and off

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Corrupt_Reverend

Corrupt_Reverend

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'72 Dart Custom Sedan.

Alright, this one is baffling me and I'm not sure where to start looking.

Last Monday, I parked my car after coming home from school. I've had no issues that lead up to this.

Tuesday morning, I go out to my car and it wouldn't start.

The dome light was on, and the buzzer came on when I put the key in, but I just got a "click", then the buzzer stopped, and the dome light dimmed.

I've gone out a few times to try to figure something out but there doesn't seem to be any method to the madness.

Just now, I went out to work on it. Initially, the buzzer wouldn't come on and the dome light was dim. I checked the bulkhead connectors, wiggled the connections at the relay, checked the battery terminals etc. Still nothing.

I crawl under the dash and double-check the fuses. None are blown. But as I'm down there just staring at the fuse panel (not even touching anything), the key buzzer comes on and the dome light pops back to regular brightness.

Hoping that I'd stared the gremlin into submission, I turn the key. Just got a click, the buzzer stopped, the light dimmed, and I'm back at square one...

The battery is good. 12.44V

At first, I thought maybe it was the ignition switch, but I don't see why that would effect the dome light when the key isn't even in.

I cleaned up the bulkhead connectors about a year back and gave them some anti-corrosion stuff so I don't think that's the problem.

All the fuses are good, but I don't know if there are any fusible links elsewhere.

Anybody ever have similar issues? I don't even know where to start looking. It's like the entire system just crapped out.
 
12.44 Volts does not a good battery make.

I'm betting it shorted a cell.

If you don't have an effective load tester, put your multimeter on and have a pal hit the starter for you. If it drops below....8V (More like 10, but the condition of the battery is unknown), the battery is DEAD. Not recharge dead, more like Robin Williams dead.

I'm betting it will drop to like 0-2V.

I've had more than one battery die in such a manner. I've literally stopped to grab something, come out of the house 2 minutes later, and the grim reaper was harvesting another voltaic-pile soul.

Rule number one on ANY electrical diagnostic: VERIFY THE BATTERY. Remember, there's more to a battery than volts. It has to be able to throw current to cut mustard.
 
Remove the battery clamps and CLEAN them

Then do some troubleshooting if it still does not work.

Get some clips for your meter. "alligator" clips and or "clip leads"

Turn on the headlights, they come on? Turn the key on and turn on the heater blower. This is to provide a LOAD.

Set the meter for voltage, stab one probe right into the positive battery POST and the other probe onto the starter relay battery stud. You should read almost ZERO volts

Now the ground. Stab the probe into the top of the NEG battery POST, and the other first on the engine, then a "body ground" point such as the voltage regulator mounting flange. Again you should read ZERO

If this all checks out, watch or have someone watch the headlights and wiggle the 'eck out of the firewall connector.

If that is OK, CAREFULLY feel back around the ammeter up under the dash for heat or looseness.

If you find nothing there, carefully make sure it's in park or neutral, and jumper the starter relay, see if it cranks. Just jumper across the two big exposed starter relay terminals.


If THAT does not work, try to clip your meter down on the large starter terminal and to engine ground and jumper the starter relay. Read voltage while jumpering.

Post back here
 
Thanks for the tip Jos! I'm terrible when it comes to batteries. I thought >12v was good-ish? I've heard about shorted cells but didn't know how to test for them.

I think I'll just take the battery in and have them test it. It is a 2+ year old walmart battery so I wouldn't be surprised if it's gone belly up.
 
Corrupt_Reverend said:
I thought >12v was good-ish? I've heard about shorted cells but didn't know how to test for them.

I think I'll just take the battery in and have them test it. It is a 2+ year old walmart battery so I wouldn't be surprised if it's gone belly up.
Click to expand...

Voltage on a sitting battery will only tell you if it's fully charged, or partially / fully discharged. A bad cell can give similar readings WITH NO LOAD

Far better is "under load tests" Which is what I posted above, "in a backyard" sort of way.

No need to test the battery until it's charged, IE you cannot test a low batter.

Here's one "state of charge" chart, so your reading indicates it's around 70% charge, and SHOULD be good enough to crank and start the car

To be clear, the readings below are "no load" on a sitting battery. Don't depend on these right after charging, known as "surface charge"

battery-state-of-charge.jpg
 
Corrupt_Reverend said:
Just now, I went out to work on it. Initially, the buzzer wouldn't come on and the dome light was dim. I checked the bulkhead connectors, wiggled the connections at the relay, checked the battery terminals etc. Still nothing.
Click to expand...

67Dart273 said:
Could be just battery connections. Very first thing I told you, did you do that?
Click to expand...

He says he did.
 
Ok "simplified" a bit

Get yourself a screwdriver, etc so you can jumper the starter relay

Use an alligator clip on at least one lead of your meter, and make these tests, WITHOUT jumper cables.

1...One probe clipped to engine somewhere, the other probe, "stab" into the top of the NEG post. Not the battery clamp, the post. Crank the engine and take a reading while cranking.

2...One probe carefully clipped to the starter "big stud." Stab the remaining probe into the POS post of the battery. Not the clamp, the POST. Crank the engine, read the meter while cranking

3....If you can round up a helper, stab each probe into the top of each battery post. Jumper the relay, read the meter while cranking

4...If you cannot do 3, , clip one probe to the starter "big stud." Hold or clamp the other post to the engine block. Jumper the relay, read the meter while cranking.

Post results back here
 
So... I got it running.

You ready for this 67?...

I, uh. Well... I cleaned the terminals and clamps.

Now, I did check them and they honestly looked fine to me. No white build up or anything. But they weren't nice and shiny.

So I though to myself, "Self, ya know 67dart273 really put a lot of emphasis on them posts being clean and the clamps tight. Now I know ya already checked them out and they didn't seem unreasonably filthy or corroded, but 'ol 67 has helped us out a lot in the past. Just to be sure, let's do this before going any further."

So we did (myself and me), and sure enough; fired right up.

I don't mind being wrong. I'm getting pretty good at it actually. I definitely don't mind it when it saves me a hundred bones!

So, big humble thanks to 67dart. You were right, and I was not nearly thorough enough in my initial assessment.

Thanks to jos for your input as well.
 
Corrupt_Reverend said:
So... I got it running.

You ready for this 67?...

I, uh. Well... I cleaned the terminals and clamps.

.
Click to expand...

Well I tell ya, in my "yuth" I was tricked by this "a couple of" times. Once was when I bought a brand new battery. I cleaned the CLAMPS but not the battery posts. Hell they looked GREAT.

Put the battery in and would not crank. Didn't take long to figure out, but I still remember that.
 
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