My 2009 Sedan G37S was in the garage for a week while I was out of town. When I went to start my car the morning after I returned, it would not start.

The brake pedal depressed normally on the first attempt, but it just spun and spun and never started. After several spins I turned it off. After trying to crank a second time, the brake pedal was very stiff, and the car continued to spin and spin, and would never start. All lights and accessories worked, the car just wouldn't fire up.

I checked the battery, it read full, but I went ahead and hooked the charger up just in case.

I let the car sit for a while and went to crank it again. The brake pedal was still stiff, but all it would do is spin, no start.

Frustrated, running out of ideas and being inexperienced with these newfangled computer-controlled contraptions, I popped the shift lock tab and shifted the car into neutral - at which time the brake pedal depressed normally. After releasing the shift lock button, however, the brake pedal returned to its stiff state, and would spin and still never start.

At this point I realized the issue was out of my hands. I called Roadside Assistance and had the car hauled to the dealership. The dealership was helpful and had the issue resolved the same day.

Solution: According to them, they have seen this issue before, but it is rare, and seems to be isolated to the 2009 year model.

Here is what the invoice states:

"Car will not start. Spins over but will not crank up. TSB reprogramed [sic] ECM, replaced battery and vent control."

Service Bulletins:
DE97AA - ECM Reprogram
GB16AA - Battery Low Voltage, No Start
FC50AA - Battery Low Voltage, No Start

Parts:
Valve Assembly - Control 14935-JF00B
Infiniti Battery- 99M1-QC24F15

So they reprogrammed the ECM and replaced the vent control valve and the battery. The best the service adviser could explain it, it was some way that the computer interacted with the battery and the brakes that caused the perfect storm for this issue to miraculously occur.

So my question is, what in the hell actually happened to cause this? What is the vent control valve? The car was working fine, then sat for five days, then this. How did it happen? I have noticed over the past few months that cold cranks were noticeably weak, but even during those months of the weak cold cranks, the battery was still reading full. I don't know if that has anything to do with it, but since the update, new battery and new valve, cold cranks have been peppier than ever.

I also just wanted to post my experience so someone else running into this would be able to save themselves a headache.

And props to Roadside Assistance. They were fast, on the ball, and the tow service they used was very professional. The driver was happy to drive me to the dealership with the car, and took great care of the car while loading and unloading. The dealership had the car repaired the same day and ready for me to drive out of town with it.

 

The valve assembly was done to replace an older style one that drew current even when the car is turned off. The TSB was issued to fix G37 with battery draining issues.

The brake pedal being stiff is a symptom of the engine not starting. It is not a cause of the engine not starting. The engine provides vacuum assist to the brake pedal so that the brake pedal is easy to press. With the engine off, there is no vacuum assist and after the first couple of brake pedal presses, you used up the residual vacuum in the brake booster. This is perfectly normal. You can go to your car and experiment this yourself. Dont turn on the car, just pump the pedal. On the 3rd or 4th pump, your pedal will be stiff. As soon as you turn on the engine, the vacuum will be drawn and the pedal will be soft again.

 

So the valve was the real culprit - and it explains why the battery might die after the car sitting for a week. That being said, why then did the car not start after I jumped the battery?