What would cause a 2007 Jeep Grand Cherokee to show symptoms that the battery is dead when trying to start in cold weather?

When this happens, not all the time, sometimes first start of the day, other times after driving for 10-20 minutes, it won't crank, a bunch of warnings and lights trigger, bit nothing on the code reader, then finally goes dead and won't try to crank at all.

The battery is actually at 12.5v, new, and disconnecting and reconnecting the battery fixes the problem and it's always started right up after.

Ideas before I head to the shop?

TIA

Alternator/ voltage regulator.

That's what I'm looking at.

Did you do a load test on the battery?

Coincidentally, I'm having starter problems with my 2001 Australian Jeep Grand Cherokee right now.
Here's my rundown of tests:
1 - Make sure it's in Park or Neutral (you'd be surprised how often this is the problem)
2 - Check the fuses, relays, etc. Swap them if needed to test.
3 - Even if the battery says it's good, try jumping it anyway
4 - Be sure to Lock / Unlock with the key in the door to disable the starter kill that comes into play if the battery gets too low.
5 - The old tried but true, hit the starter with a hammer trick

If it's still not cranking after all of that, I think it's time for a new starter.

Mine is in the backyard right now with a new battery and a new starter waiting to be installed whenever I get motivated enough to do it.

The last time I replaced the starter in my Grand Cherokee was about 15+ years ago in my driveway in Collaroy, NSW.

Thanks!

Trying to decide if it's the starter or some computer acting up.

Interestingly, letting it sit in the ON position for 5-10 seconds diesel still works most of the time. Today it didn't. So far the Battery reset is undefeated.

which cable are you connecting/disconnecting?

are the cables/connections in good condition at both ends?

sts7049 said:

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which cable are you connecting/disconnecting?

are the cables/connections in good condition at both ends?

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I've got a quick disconnect on the battery itself. The car sits a lot at times. It's the screw kind.

for me there is something odd about you unhooking and rehooking it up. it could be a crap battery, but that wouldn't make a lot of sense for it to just be OK after you disconnect it and reconnect again.

is there a chance that quick disconnect you have on is junk or corroded? something tells me either you have a poor connection or ground.

sts7049 said:

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for me there is something odd about you unhooking and rehooking it up. it could be a crap battery, but that wouldn't make a lot of sense for it to just be OK after you disconnect it and reconnect again.

is there a chance that quick disconnect you have on is junk or corroded? something tells me either you have a poor connection or ground.

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The connection has been trouble before. Gonna keep a closer eye on it.

I wonder if your TIPM is on the way out…..

Well in the summer, in certain temperature ranges, the Gas Cap message comes on. The mechanic said a board was supposed to be getting 5v to keep the message off, and it wasn't always getting it. It passed a smoke test and the EVIC is toast as well.

It started life as a State vehicle in WVa so no telling how messed up it is with various mods I can see remnants of inside.

I need to get 3.5 years and probably 20000 more miles out of it.