2012CGS

My 2012 GS has the NPP exhaust options. I have been using a Mild to Wild switch. About a year ago it stopped working. Fuse is OK. any thoughts about what to check next?
Thanks in advance for your help.

Chiselchst

Check to see if the actuators move freely on the exhaust tips. Check both sides. Ensure the vacuum lines are connected.
Check to ensure you have vacuum at the actuators with the valves in the closed position (with the engine running).
If there's no vacuum, it's either a vacuum leak or the switching mechanism isn't functioning.

Chiselchst

I'm assuming it's stuck in the open position?

GREENKAR

Don't forget to check the batteries in the m2w fobs . I had that problem. Very

FatsWaller

I'd first remove the M2W switch and replace the EXHMDL fuse to check that the system operations normally - both valves open with engine off, and both closed when you start it. If that functions OK, then the M2W switch or fobs have a problem. If not, the problem lies with the vacuum solenoid or vacuum lines, or maybe even the actuators, although very unlikely they'd both go bad at once.

d.medic

https://www.corvetteforum.com/forums...thier-z06.html

dr_gallup

It's usually the solenoid valve that fails. Mine has stopped working too. The GM solenoid valve part number is 25794609. If you google that you will also find a lot of hits for a similar but cheaper GM 25794610 which is interchangeable.

C5forGreg

Agree. I bought my car last year and the NPP was stuck open. Checked the fuse and even replaced it and nothing changed. I was going to troubleshoot and fix it myself but I prefer to be open most of the time anyway. When I had the car in for service, I asked them to fix it and it was the solenoid that was the problem. It's working now, so I promptly put in my M2W switch and still keep it open most of the time anyway.

lwise4

Mine was doing that and I replaced the solenoid. Fixed it! In my 08 I removed both right rear taillights and it was easy to change out.

DaLongRanga

Where's the vacuum lines located ?

kestell123

The accuators don't need to both be bad for both to stay open. If one is bad the vacuum leak can prevent both from closing. This was problem when I bought my GS. I pulled the hose off the bad one and plugged it and the other side closed. I found a used one and have been good for 5 years.

kestell123

The vacuum line runs from the rear of the intake manifold to an electricly controlled solenoid behind the far right tail light. from there to the vacuum acctuators on the mufflers that close the valves when vacuum is sent from the solenoid.

DaLongRanga

Found it , but there was a little hose came off my valve on the npp exhaust right by the exhaust tip .... i plugged it back up and it closed .

Steve M93

I have a question about your NPP exhaust switch or button looking at a 213 grand sport that has the MPP factory option the original owner and I cannot find the switch. Can someone send me a picture or tell me where it’s located. Thanks

gdmoore01

I think you are asking about the location of the NPP solenoid? If so, the below thread should help you. I would also suggest you start a new thread when requesting assistance. Some members do not look at the old threads.

https://www.corvetteforum.com/forums...placement.html

Good luck...GD

kestell123

If you are refering to the Mild to Wild control to manually open the exhaust, it is not a factory piece. It can be easily added with either a wireless remote or a hard wire switch . Do a Google search for it because the search on this fourm does not work well.