wrong voltage reading
 

Hey all,
2003 Buick Park Ave. 3800 V6.
I thought I had a weak battery because my dash readout said it was 11.5 volts with the key on, engine off. but when running it read 12.5 to 13. every time I shut the car off and would turn the key back to on, the gauge would say 11.5 volts. so I took the battery out and back to the store because it still had a warranty, they checked it and said it was good.
long story short, I ended up damaging the battery so I got a brand new one.
Only same thing. gauge reads 11.5 volts with key on, engine off. 12.5 or more with engine running.
took a multimeter and checked the battery and it reads 12.6 volts with engine off. turn key on and gauge says 11.5 volts.
car starts fine every time.
anybody ever seen this before? possible PCM problem? I've had electrical issues with this car before and fixed them. most were shorts or opens.
any suggestions appreciated!

You have a bad connection somewhere. Check and clean all of your battery connections.

will do!
Thanks

What Mike said ^^^^^^^

. . . plus: Don't rely on the dash gauge for accurate voltage readings. It is meant for general reference. In your case it looks like 11.5 means 12.x in real life.

Big question here is: With the engine idling and accessories and lights turned off, what does the multimeter read at the battery terminals?

engine running, all acc. off. at battery reads 14.5 dash gauge reads 13.3
engine off battery reads 12.5 and gauge reads 11.4
all connections at and around battery are clean.
I just thought of something though, I removed the IP last fall to replace bulbs and I took all the needles off the analog gauges, but the voltage readout is led. could I have done something to the IP? I mean I know I could have, but I was very careful. I think, LOL. Oh well any ideas?
I just remembered too, no kidding, if the car sits for a couple days or more when i first start it the wipers start and make one pass, then go back to off, and the switch is in the off pos. this just started a couple weeks ago. I think I have Gremlins! I I drive the car everyday it doesn't do it!

This is good.

This is good.

I doubt it. If it reads anything near accurate it's probably not because of anything you did. I'm going to stick with "Don't rely on the dash gauge for accurate voltage readings. It is meant for general reference" even if it is digital. There might be an analog process involved that is getting tired or something.

I've seen this a few times. Never found a smoking gun, but have solved it a couple of times by replacing the all-in-one turn signal stalk. Like I couldn't with complete certainty condemn the stalk, but it already had loose switches/etc. and had been on the car forever, and then replacing it happened and then the issue was no longer reported. MY telltale is to check the spring-loaded [accel] slider. If it feels worn out, the whole stalk probably is. This isn't 100% accurate, just my starting point.

The DIC (digital information center) voltage readings are inaccurate & are traditionally low by 1.2 volts on the PA. I simply add 1 volt to approximate a more accurate battery reading and leave it a that.
Also a known issue is the windshield wiper/washer fluid control circuit, it can have a mind of it's own! ;)
Sometimes I have to use the washer mode to get the wipers to return to park for instance.
Some times I have to use the washer to get the wipers to work, it's old, I think it has a case of dementia !! gp1
I'll also add that the switch/stalk could be wearing but as long as it still somewhat works, I'm not changing it.

For what it's worth, on my LeSabre:

- With wipers on, any speed, if I hold [wash] for less than about a quarter second, it sprays for exactly one second. If I hold [wash] for more than about a quarter second, it sprays for exactly as long as I hold it, even if I hold it a half second or 0.82 of a second or ten seconds.
- With wipers off, I can usually hit [wash] one time or some larger number of times, for a short interval or long, which should spray (based on the rules above) and wipe at the same time, but it won't do anything at all. Then, any amount of time later (without shutting off ignition) if I turn on the wipers to any speed, it remembers that I requested [wash] and sprays for exactly one second. One out of a hundred times it works correctly ( [wash] unparks and turns on wipers for pre-programmed duration including and beyond [wash] activation, then stops spraying and parks wipers) .

It's been this way for 18 years and 160,000 miles so far.

I put this all here because the same folks were conceptualizing/designing/programming your system moments after mine so similar thinking probably went into them.

thanks guys, sounds like no big deal then.
I did forget to mention that it has auto sensing wipers, but they aren't supposed to come on with the switch in the off position as far as I know. might get a new stalk, not sure.
I'm relieved to know the battery issue is nothing to worry about.
car is in excellent condition for its age and 255,000 miles on it.
Thanks to All.