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Alexandra - 96 SDV Clyde - 15 Silvy
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Discussion Starter #1
Alrightey, so here's the story from the top:

Last week of October 2012, I changed my oil and my oil level sensor. Sensor didn't work so I checked my voltage offhand. 11.3 volts. Way low.
After some troubleshooting, I figured out everything had to be turned off to get the reading. At that point I got 12.1 Volts. Still a tad low.

I figured nothing much of it, half a volt low, old car, no apparent issues, so I carried on.

Over winter break the issue came to my attention. A couple of coldish nights, such at 15-20 degrees F, I would see voltage readings of 10.7 or so. This was with my headlights, seat warmer, and radio on, but still alarming. The weird thing was that, other than a few seconds to start, there were no issues, or codes.

Fast foward to the weekend of February 9th, and the issue gets really weird. It was single digits when I was out and about, and I saw some 10.8 volt readings when I first got to the car. Started up just fine. Went to Walmart, ran my errands, came back out and saw a 9.8 volt reading :jawdrop:.

Even with the 9.8 volt reading, she fired right up and took off, no issue.

Needless to say, that scared me. So, this past friday night (the 22nd), I did the basscatt battery test: Drove around for an hour, parked, turned off all accessories, shut 'er down, and then disconnected the battery. I heard that cold may affect a battery, so FWIW, the lows Friday, Saturday, Sunday, and Monday (I let 'er sit because I was busy) were -2, 14, 0, and -14, respectively.

This afternoon, I hooked the battery up, climbed in, and turned the dash on. 11.6 volts. :hmm:

Drove around for a bit, parked it, shut off all the accessories, 12.1 volts engine off.

Some background that may or may not help:

Transmission was serviced Sept '12 , new internal harness and ISS. I highly doubt they muffed anything up.

Captain Clutz dropped a socket into the engine bay while monkeying around. It is magnetic (other sockets in the set are), but fishing trips have been unsuccessful.

I changed the spark plugs in August '12. I went back the weekend of the 16th and cleaned everything up, as well as checking the involved contacts. That didn't change anything, so I doubt that was an issure to begin with.

I cleaned the attachment for the black cable (onto the engine) as well as the battery contacts, and made sure those were snug (weekend of the 16th).

My right side heated seat module is acting up. With the heat setting to low, whenever I signal a turn, so does the module :cookoo: .

The alternator, AFAIK, is stock. I have NOT had it tested at any point (do they test for fried diodes?).

The battery is a year and a half old (replaced June 2011). Diehard.

FWIW, when the battery read 9.8 volts the weekend of the 9th, After I restarted the car, I got an IP1552 HISTORY code. Cleared it and it hasn't returned. Other than that I have had NO codes.

When the car is on, it ALWAYS charges right around 14 volts.

What the heck is it? At first I thought maybe that dumb socket, but now maybe the battery or a burnt out diode?
 

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2010 DTS
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If you are "running" at 14v or better and have no problems starting, ignore it and stop obsessing over it. It'll let you know when it's time to change the battery.
 

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Alexandra - 96 SDV Clyde - 15 Silvy
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Discussion Starter #4
If you are "running" at 14v or better and have no problems starting, ignore it and stop obsessing over it. It'll let you know when it's time to change the battery.
Sounds good. :thumbsup: I was wondering why there would be anything wrong if she started fine, and charged the battery perfectly fine. Thank you guys.
 

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Alexandra - 96 SDV Clyde - 15 Silvy
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Discussion Starter #5
FWIW the voltage issue turned out to be a bad voltage regulator. Symptoms included hard starts when cold and dimming lights when brakes were applied.
 

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Cadillac Technician
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Open circuit test voltage on a battery should be ideal at 12.6 volts.
Using the DIC reading is not a good idea on a non-running car. You are placing a load on the battery key on, lights, clocks, little fans, sensors, and the like will place a load and cause a voltage drop to the battery.
Cold weather can have serious effects on batteries and voltage readings. I would agree with others that you might expend your energy worring about something that is actually a problem.
 

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1979 Coupe deVille, 1995 Sedan DeVille (sold)
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Thanks for the follow-up, Luke!

I like it when people post back with the solution :thumbsup:
 

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Alexandra - 96 SDV Clyde - 15 Silvy
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6,428 Posts
Discussion Starter #8
Open circuit test voltage on a battery should be ideal at 12.6 volts.
Using the DIC reading is not a good idea on a non-running car. You are placing a load on the battery key on, lights, clocks, little fans, sensors, and the like will place a load and cause a voltage drop to the battery.
Cold weather can have serious effects on batteries and voltage readings. I would agree with others that you might expend your energy worring about something that is actually a problem.
I know that. The only things I had on when checking the voltage were the dash and the clock. That was it.

If it helps any I got 5 tests confirming the original voltage regulator was bad, during the summer.
 

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Are you testing at the battery or looking at the DIC display?
The ONLY place to check battery voltage is at the battery with a meter. The gages/instruments are meant to be a representation, not a precise means of measure.
Anyway, sounds like you are satisfied that it is in good shape.
 

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Alexandra - 96 SDV Clyde - 15 Silvy
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Discussion Starter #10
Are you testing at the battery or looking at the DIC display?
The ONLY place to check battery voltage is at the battery with a meter. The gages/instruments are meant to be a representation, not a precise means of measure.
Anyway, sounds like you are satisfied that it is in good shape.
Both. The battery has been tested at Advance and Autozone multiple times, and comes back great (~13 sitting IIRC).
 
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