Hi Folks! Here's the backstory:

Son's been driving my 2005 5/AT and a few weeks ago he mentioned that when he tried to start the car, sometimes it turned right over and other times it took several more cranks. Checked battery cable to terminal connections and they were tight.

Then about a week ago, the VSA and yellow triangle with exclamation point lights come on, but car is still driving fine. Codes pulled with scanner:

25-01 - Yaw Rate Sensor Failure
64-01 - Sensor Supply Voltage Failure

Couple of days ago he couldn't start the car, but the interior lights would come on. Battery was only about a year old, but batteries are often at the root of wierd electrical issues and fail frequently here in the desert, so he gets a new one at Costco.

Everything was fine for a couple of days, but then he calls and said car is completely dead. No crank, no dash lights, etc. I drive down there and use a battery pack to jump it without issue and drive it home. The drive is about 40 miles, more than enough to recharge the battery. Also noticed that the idle was a bit rough and while at a stop light would be dipping from around 750 to 500 RPM before popping back up to 750.

This morning I go out to start the car to pull it into my side-drive. Battery seemed a little weak, but it did turn over. Idle was slightly rough, but stable.

Perhaps there's an electrical drain somewhere?
Issues with the alternator?

So, I'm just looking for how and where to start the troubleshooting process. All these issues could be unrelated, but suspect that they are in some way.

All thoughts and suggestions welcome. Thx!

 

Have you unplugged or removed the HFL module? That is a known battery drain issue. It’s located up above behind the map lights.

 

Yah, thx, did that years ago. There's actually no drain. Had battery, alternator, and starter tested and all were fine. Changed negative battery cable, but still nothing: completely dead. If I hook up a battery tester/charger to the battery when it's installed in the car, there's no reading, but if you take the cables off, it's fine. Remember that when I tried to jump it with two different jumper packs, they both registered errors like "short circuit" and it wouldn't turn over at all and no dash lights, just dead.

Feel like it's got to be:

1. A short circuit or problem with the positive cable
2. A bad fuse or relay
3. Other?

Thx!

 

Have you flexed the battery cables to look for hidden cable corrosion? Mine had corrosion that was very obvious, but other's have posted over the years that the cable was bad internally further from the battery.

1.) Check battery voltage at the terminals with car off
2.) Check battery voltage at the fuse block with car off
3.) Check battery voltage at the terminals with car on
4.) Check battery voltage at the fuse block with car off
5.) Next time entire car is "dead"
- check voltage at the terminals
- check voltage at the fuse block
- jiggle all battery cables and see if anything changes

My vote will still be bad cable.

 

Corrosion, in your cables. Green funk. Groun cable, alternatir cable, starter cable. Check cables. This was my issue. Hope you solve your issues. Good luck

 

My bet is you are seeing multiple unrelated issues.You could have issues with the alternator, battery, starter, and sensors. Let alone wiring. If all of your cables look good, you may also want to make sure they are tight. I've seen alternator cables loosen, which cause all sorts of issues.

If you can, always before you start the car, check the battery voltage. That will help you at least eliminate a weak battery and drain.

My 05 has the HFL drain, so I just unplugged the HFL. The battery would be less than 12 v after one week of no long drives.

My 05 original starter started acting up in 2023. I would occasional hit a flat spot...