Don't discount the possibility that the problem might be due to a weak battery in the key fob, too.

 

You would either get a "key not detected" or a "replace key battery" n that case. You can still start without a battery in the fob by placing it on the start button until the light turns green, moving it aside and pushing the start button.

 

Well, it is the battery, it happened again today, and I was able to get it started by putting on a battery charger for a few minutes. It seemed to take a charge fairly quickly, but it wouldn't hold for long. Definite sign of a dead battery. i looks like an Optima or something like it is on the list for tomorrow.

 

Semi-desperate measures... Couldn't get to the battery store for a replacement, so I put the charger on the battery overnight. I have a dual rate 6 or 2 amp charger, so I set in 6 amps overnight. The car's worked like a champ ever since, no problems.

Since it's my wife's car, and she only does occasional short trips, maybe it hadn't been recharged by the charging system, and the "sleep mode" drew enough to pull the battery down.

Still, I'm going to keep a close eye on it.

Somewhere around here, there are instructions to get into the diagnostic screen. I'm going to dig that up, and see what that says.


Also:

People have been telling me that the Optima batteries are not very good. Since they were sold to Johnson control, the plant was moved to Mexico, and the quality has taken a severe dive, is the consensus. Comments???

 

Have you tried checking the 12V battery voltage. See the link below. About 80% of the way down the page they give a chart which estimates battery charge based on voltage.

Battery Info

I would check voltage 20 minutes after it has been out on a drive, and then check it again after it sits overnight (both with it in the Off mode). you may get some idea as to how charged the battery is, and when it is losing the charge.

Also check voltage when it is in the on (Ready) position. Here are some numbers that I got with a new vehicle:

Overnight - 12.92
After 2 weeks sitting - 12.53
In Ready mode - 14.63
Immediately after turning Off - 13.23
After 20 minutes Off - 12.93

If you are not up in the 14.5V range when in Ready there may be a problem with the charging system.