Another electrical gremlin thread

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PPV_2018

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my turn to ask for help.

Short TLDR version: Power locks have gone total apesh*t. Never was a problem until.. our first cold spell. ‘Cold’ being about 45*F outside.


Here’s what we KNOW:

-Tahoe PPV with dual battery set up.
-Truck comes from rust belt and as such:
-Both the chassis ground on passenger side frame rail and grounds on driver side frame rail were quite rusty and corroded. Cleaned these grounds thoroughly with wire brush (more on that in a sec)
-Cleaned all battery contacts, terminals, and the terminals at the battery isolator relay
-Secondary battery has a date of 12/21..making it exactly 3 years old. It is also a cheapo no name brand battery.. so I’m thinking “problem”
-No date on primary battery. It is AC/Delco

Using a digital multimeter:
-Primary battery is reading 12.66v (one hour sitting)
-Secondary battery is reading 12.54v (one hour sitting)
-Charging system is reading between 14.4 and 14.5 between both batteries

BACKSTORY:

Last week we had our first “cold” of the year. About 45*F. After a short drive up the street I parked the truck and as I was getting out swore I heard the power locks activate, but wasn’t entirely sure and the door was unlocked because I had just opened it.. I pressed the door lock button on the door and went inside.

Next morning, it’s a bit warmer out. Around 55*F and sunny. go to get in truck and it is unlocked. Thought it was weird but didn’t think too much of it again.. maybe I pressed the door unlock button while coming out on key fob and didn’t realize it. Go to get breakfast, door locks start freaking out. Unlocking itself every 30 seconds or so.. keep it mind that it is only the driver door lock unlocking itself, not any of the others.

I’m actually off this day so I decide go drive around for awhile, truck stays locked, no issues. Then it begins acting temperamental. Unlocking itself in various increments of time, anywhere from 10 seconds to 15 minutes or more without issue before again unlocking itself. Watching the dummy gauge on the dash, it’s reading below 14, roughly 12V. Some time later, Dummy gauge eventually goes up to over 14V. Problem persists.

It is getting considerably worse. Dummy gauges read 14v. Now I cannot lock the vehicle at all without it unlocking itself within 5 minutes. To some people, this is just an annoying gremlin. To me though it is a much bigger deal. I live in very high traffic, NOT very good area, with a lot of creeps and weirdos regularly passing by on foot and car. Even worse, just a couple of months ago our household was a victim of auto theft when they stole my wife’s car right out of our driveway. Not being able to lock the truck is a major security issue and it’s pissing me off BIG time….

Pics of GROUNDS:

Before
urckgh5.jpg

After
bedKlwa.jpg

Before
k5eUmXb.jpg

After
vErtnaH.jpg

And a little more info on those grounds… The chassis ground on the passenger side frame rail was actually somewhat loose when I took it off !!! Not super loose but it was NOT tight as it should have been. When I went to reinstall the bolt after cleaning, it just threaded indefinitely but would not tighten. Not even a little. Great. I went into my stash of extra bolts and pulled out one that was similar. It did tighten but not as much as I wanted, it too, just spins freely. I got it basically to stay at “hand tight”.. being where our roads might as well be gravel highways I’m definitely worried about it coming aloose. How big of an issue is this ?

Was thinking the secondary battery is bad but would it really cause this kind of issue? I’ve had many a batteries go weak and/or die on me over the years and never experienced anything like this. Also I’d be gutted if I went and spend $200 on a battery for the freakin door to start unlocking itself again once I put the terminals back on…

So, battery bad? Alternator bad? something else?


I would be most gracious for any advice.
 

PG01

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Kidding above….

Actually sounds like your loose-ish ground is the problem and make sure your door switches are working, as in the latch on the door that go to the b and c pillars…
I would take a screwdriver and ‘close the latch’ with all the doors open and lock them then play with the latches a little especially the drivers door.
 

Fless

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My driver's side ground on the body mount was stripped so I used a bolt and nut there, with the head toward the tire. I didn't want to subject the bolt end threads to what the tire tosses up.
 
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