Had a bizarre issue with my 2008 G35X Sedan this morning.

A coworker came to my office to tell me my lights were on. My exterior driver's door handle broke recently so as I walked out to my car I used the fob to roll the windows down half way so I can reach in to open the driver's door. I got in the car, the start button cycled to "ACC" and "ON" when pressed but the windows would not roll up.

Car wouldn't start, headlight switch was in the OFF position when I got to the car. I grabbed my NOCO booster from the trunk, the car tried to start but just cranked for a long duration without starting.

I'm at work and we have CR2032 batteries in the office so I replaced the battery in my key fob. This did nothing, disconnected the battery and when I reconnected the battery the headlights (HID's) marker lights and full tail light assemblies light up. There is no power to the interior of the car anywhere at all. No interior lights when I open the door or press the map lights. The start button does nothing. Power locks don't work with the key.

Thoughts?

 

Did this happen during or right after heavy rain?

 

It did rain this last night into this morning yes. Freezing rain turned to rain, temperature just above the freezing mark.

Very odd issue in how it got progressively worse. Battery has 12.5 Volts (I checked it with a volt meter).

It's strange that when I hooked up my booster pack the car tried to start twice but would not. Putting the key fob in the port near the trunk pop didn't work either.

I'm thinking of chasing grounds after work in the shop when I get a chance but would like to narrow it down. There is zero power inside the car. No courtesy lights or map lights when the door is opened. The key fob does nothing, no lock/unlock on the fob or pushing the buttons on the doors. And as soon as I hook the battery back up all of the exterior lights are on including the HID's eventhough the headlight switch on the stalk is off?

 

The reason Scorpi0 asked about rain is because it sounds like your IPDM has gotten wet. Those are so many odd electrical issues to happen at the same time that you should look into this as the possible cause. Not easy to get to behind the battery but if it got hosed then you know why your car has lost its mind.

 

I was thinking something along those lines or bad ground(s). I have been checking around online in the meantime and am going to start with the IPDM then move onto the BCM if I don't see results.

Thanks for the help, I knew with the strange myriad of electrical issues all at once it had to be a broad part problem rather than a singular component.

 

That is not the correct way to test a battery.
Use a battery hydrometer to test the individual battery cells.




That is because your booster pack did not have enough amperage

IYour problem is most likely a discharged, weak, or a dead battery cell not accepting a full charge.
If you can't remember how old the battery is, just replaced it.
Carefully inspect both battery cables.

Good luck

 

Battery is not very old I replaced it myself within the last couple years, I also tried boosting the car hooking it up to a Silverado with booster cables.

I am leaning towards the IPDM as a starting point.

I appreciate the reply.

 

Did you try measuring the voltage across the battery with the booster cables connected while attempting to start the vehicle?
A shorted cell in your battery would cause a significant voltage drop preventing your vehicle from starting.
Prior to looking at your IPDM, remove the battery from your vehicle and temporarily use the battery from your Silverado
Another way to observe a battery voltage drop is to put the headlights on and then try to start the vehicle. If the headlights go out you have a defective battery.

 

There was no ability to start the vehicle by the time the issue progressively worsened and the car had zero voltage going to the interior of the car and the headlights were stuck on with the battery connected.

I winched the car onto our 4post lift in the shop. By the time I was finished my work day and got to tinkering with the car at night, it had dried out and was operating completely normally.

I'm going to use our load tester on the battery to check it. I pulled the IPDM out of the car. Stripped the casing, split it open to the circuit board. No signs of water anywhere, could be a bad component affected by moisture in the air. Going to remove all the grounds and clean them up, re-install them. It's obviously an issue affected by moisture in the air or something else getting directly wet.

 

The other spot to check for water is the front passenger footwell. The drain from our sunroofs which runs through the A-Pillar has been known to fail and bring water into the cabin there flooding the BCM. But your combination of issues sure sounded like the IPDM, so don't really know. Hope you find something while checking all the ground points.