Have a 2011 C6 Grand Sport manual transmission with no options or after market modifications other than chrome wheels. It does have an Escort Passport radar detector powered by a connection made in the rear view mirror power block. It uses the standard BlendMount connection for this. This connection has been there unchanged since 2011, about 8 years before this problem started.

Mileage is just over 7k.

When fuse 13 is in the fuse box (shown in the manual as "Electronic Suspension Control (Option)") the battery is completely drained in about two days. It is not known what might have caused the issue to happen, no changes were made to the car, went out to start it one day in 2019 and the battery was dead. Before taking the car out I do run a Deltran battery charger to be sure the battery is fully charged before driving, this has been the same practice since 2013. The current battery is about two years old and is an Optima Redtop 35. I had the same issue with an earlier version of the same battery.

So far removing the fuse is the only way to stop the drain. While the fuse is out this results in the Check Engine light to be illuminated constantly.

I assume the fuse has to do with the Magnetic Selective Ride Control option, which as mentioned this vehicle does not have.

Reported this to the dealer while getting routine service and they wanted nothing to do with diagnosing or fixing the problem. They did not even try to charge their "diagnostic" fee. Normally the transmission is left in first gear when parked and the radar detector is definitely not powered to the point of showing any signs of being on when the engine is off. I was told by the tech while parked to disconnect the radar detector and leave the manual transmission in reverse instead of first. After doing as the tech advised and replacing fuse 13, the battery again drained after about two days.

Is there any advice for this as to cause and remedy?

 

I have attached a copy of the electrical diagram for the Magnetic Ride Control system on my 2006 Corvette. I believe yours is similar. As you can see, fuse 13 provides power directly to the Electronic Suspension Control Module. You say that your car does not have Electronic Suspension Control, but I am thinking that it may have been originally equipped with that option, but a previous owner may have removed it and installed conventional shocks. Can you look at the RPO listing on your glove box door to see if code F55 is listed? That would be the RPO code for Magnetic Ride Control.

 

Thanks for the diagram. I am the original owner, no changes have been made related to the Magnetic Ride Control. I don't see the F55 listed on the glove box door placard, see attached picture.

 

OK, then all you can do is follow the wire coming off of fuse 13 and see where it goes to find what is causing the drain. I imagine you already knew that.

 

I did a little more digging, and discovered that the Power Distribution diagram shows additional connections for fuse 13. In addition to the Electronic Suspension Control Module (which you apparently don't have), fuse 13 also feeds the Reverse Lockout Solenoid on the manual transmission, and the EVAP Canister Vent Solenoid Valve (see attached diagram).

 

Pull onstar fuse for starters. It has a lot of parasitic drain. How old is your battery? Have you tested the alternator?

 

Seems as I recall there was an issue with battery drain in C6's when not left in reverse. That thread was many years ago and affected the early year cars until GM figured it out. When it was mentioned here that fuse 13 fed the reverse lockout solenoid it jogged my memory of that. You might try searching C6 battery drain in reverse or something like that. Sorry I can't be more specific. Here's a quote I found from 2010 - "That is correct for the 2005 6 spd manual. Placing it in reverse was used to shut of the accessories. Not true for 06 and latter."
Since yours is a 2011, probably doesn't apply.

 

Since the likely culprits seem to be either the EVAP cannister vent solenoid valve or the reverse lockout solenoid, I suggest checking on these one at a time. The EVAP valve seems to be the simplest to access, so I would start with that. Begin with a fully charged battery, then get under the car and unplug the electrical connection at the EVAP valve. Then, let the car sit for two days, reconnect the plug, and try to start it. If the battery is too low to start the car, then the problem wasn't related to the EVAP valve. If that is the case, then do the same test on the reverse lockout solenoid. I am attaching a video that shows the replacement of the EVAP cannister vent solenoid valve. I think you will find it helpful for finding out exactly where this valve is located on your car.

 

This would be an excellent time to drop less than $50 for a DVOM, and learn how to use it. On a C5, the EVAP/purge valve connection/plug-in is on top of the intake manifold. Can't be sure about a C6. If it's accessible up top like the C5, it'd be a Helluva lot easier than crawling under the car. My .02.....

 

The EVAP purge valve is at the front/top of the engine on C6 too, but unfortunately that valve isn't part of this problem. The possible culprit in this discussion is the EVAP cannister vent solenoid valve.

 

OK, I stand corrected. Sorry. But a DVOM would still be helpful......