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Wireless control of rear C7 NPP exhaust valves via wireless fob or Homelink - How To
NOTICE: If you decide to construct and install any hardware based on the information below, you agree to use it at your own risk. If you short out your wiring harness or otherwise damage yourself or your car or burn your house down, I assume no responsibility whatsoever. The circuit appears straightforward, has previously been used successfully by others and works well for me. If you decide to attempt to build and install the exhaust valve controller, fully read the full post a couple of times before proceeding. You might want to wait a week or so for others to chime in and note errors, corrections or add additional information. If in doubt about the procedure or your ability, think twice before proceeding and ask questions as there are people on this forum who know much more about the modern electronics in these cars than I do. All work done within the fuse box while the cover is removed must be done with the ignition OFF.
The following instructions are for 2015 C7 with the NPP exhaust option.
UPDATED 1/1/18: New info from user Capehorn3 indicates changes to the fuse box layout on 2018 Stingrays eliminates the space required for the circuit board (even with cut down circuit box).
UPDATED 9/9/16: Added NPP Exhaust Valve control fuse info for 2017 C7. Same fuse number (42) and general location as 2015/16.
UPDATED 6/22/16: Added a link to the illusive electrical ground location within the fuse box discovered by user Ratz. https://www.corvetteforum.com/forums...-how-to-3.html. See post 56. The discovery by Ratz simplifies the ground wire installation and removal by keeping all connections within the fuse box. His procedure can replace step 5 below.
UPDATED 10/25/15: Added NPP Exhaust Valve control fuse info for 2014 - 2016 C7.
UPDATED 10/18/15: Modified step #1 (circuit board case) due to heat issue. I noticed the clear plastic lid I used for a base was becoming distorted by the heat in the fuse box (~160 deg F). I modified this procedure to use the original thicker plastic box base the circuit was originally housed in. I don't believe the circuit hardware is at risk from the heat. I will report back if I see issues. Heat also rendered the Velcro adhesive useless but the modified case bottom contains the circuit to a safe area.
UPDATED 9/8/15 to include Homelink control information.
2014 C7, 2016 C7 and Z06 models may require different wire lengths and different fuse and circuit board locations. If members could post clear photos of your front fuse box with the lid off and the fuse map on your fuse lid, I may be able to determine compatibility.
Using basic information gleaned from this post: https://www.corvetteforum.com/forums...-2015-zo6.html started by 'franky boy' on 7/21/15, I was able to adapt the basic information and complete the project for my C7.
I was able to install a small wireless relay board within my 2015 C7 front fuse box that allows me to open the rear exhaust valves via a small 2 button key fob remote. This circuit removes the rear exhaust valve fuse (#42 on 2015 C7) from the circuit when commanded by a remote wireless button press (which opens the rear exhaust valves) and replaces the fuse in the circuit when the second remote button is pressed (giving rear exhaust valve control back to the car computer).
Basically it will allow an inexpensive method to over-ride the computer and open the rear exhaust valves when the computer wants them closed. Obviously, if you command the valves to open and they are already open, nothing happens but when the computer wants them closed, they will not close until you press the remote to re-enable the fuse in the circuit.
Parts required:
(1) iMBAPrice® 12V, 15 Amps, Heavy Duty Boat and Car Universal Remote Control Kit, Amazon.com, $17. Free shipping. Comes with spare remote. Pic 1
(1) Lumision ADD-A-CIRCUIT ATR MICRO2 FUSE-TAP Add ON DUAL CIRCUIT ADAPTER AUTO CAR TERMINAL + 5 AMP Fuse, Amazon.com, $8.
Note: the included 5amp fuse will be harvested later for parts.
Pic 2
(1) piece of ground wire or braid wire (2 feet is more than enough). I used thin braid as it was thinner and fit under the fuse box cover easier. Local store or eBay for $4 shipped.
CUT TO SIZE /FT BRAIDED FLAT GROUND WIRE MFG #C2065-2 AVIATION GRADE WIRE See RED caution below about braid wire.
Pic 3
(1) 16-15 gauge terminal wire connectors (crimp connectors), local store. Use a proper crimp tool, not a pair of pliers.
Pic 4
(1) 12-10 gauge 5/16" ring terminal for ground stud, local store or O'Reilly Auto Parts, part # 85445, box of 11 for $3.09. I did not find the correct size at HD or Lowe's.
Pic 5
(2 or 3) pieces of heat shrink. Local store. I picked up a nice set on eBay for < $7.
127 pc Heat Shrink Wire Wrap Assortment Set Tubing Electrical Connection Cable
(1) M8 X 1.25 nut to attach ground strap ring terminal. Local hardware store.
(1) Strip Velcro (mated strips) 1" X 1 3/4" SKIP THE VELCRO - IT WON'T HOLD UP TO THE HEAT OF THE FUSE BOX.
(1) Electrical quick disconnect (OPTIONAL), local store.
Pic 6
(1) Soldering iron setup my be needed for step #4 below, unless you can figure a way to crimp the fuse leg to the wire.
Steps 1-7 can be done away from the car. Some pictures may show connections made in the car but are for reference only. Actual installation of hardware into the car starts with step #8.
Step 1: Pry plastic case lid off of remote control black box to reveal circuit board. Remove small phillips screw from circuit board and remove board from case bottom. Cut about 3/4 " off of case body such that circuit board is flush with cut case end. I used a Dremel tool with a cutoff wheel designed for plastic. See pic 7a and 14a.
Pic 7
Pic 7a
Step 2: Shorten red wire coming from circuit board to 1 1/4 inch total length. Strip 3/8" off of free end of red wire and crimp free end into blue crimp connector located on end of red wire coming from fuse tap. See Pic 11 below.
Step 3: The Fuse-Tap Add-A-circuit comes with a spare fuse. Using metal cutters or a small saw blade (not scissors) cut the spare fuse in half and trim off the plastic case until you have just one of the metal legs as shown below. Pic 8
Step 4: Shorten white wire from circuit board to 2 3/4" length. Slide a short piece of heat shrink over the wire and strip off 5/8" of insulation off the end of the white wire. Solder the end of the white wire to the skinny half of the fuse leg you harvested from the spare fuse in step 3. Slide the heat shrink up to cover joint and heat the shrink tubing as shown here.
Pic 9
Step 5: The two black wires from the circuit board are ground wires. This ground needs to be routed out of the fuse box to the ground point. I decided to use thin braid as it would be easier to mash in the fuse lid (which contains an o-ring). You may use regular wire to extend the length but use wire as least as thick as the white wire on the circuit board.
I cut the two black ground wires shorter, leaving about 2" attached to the board and crimped on a section of braid wire about 20" long using a crimp connector (see Pic 11). You may want to add more than 20" depending on the path you choose to get the ground wire to the ground point. To crimp the braid, pull and twist the end into a point so it will twist into the end of the crimp connector. Add a 4" section of shrink wrap to the braid (if you use braid instead of insulated wire) and crimp on a ring terminal (Pic 5) at the other end of the braid (or wire). If you used braid, slide the heat shrink up until it overlays the crimp connector you added to the two short black wires and heat it to shrink. The idea is to have no exposed metal braid within the fuse box. See Caution below.
CAUTION:As I was routing the braid wire out the side of the fuse box (the side next to the engine), I noticed all the installed fuses actually have live metal tips flush with the top of the fuse. I had never noticed that before. If I had run bare braid wire in the fuse box, it could have come in contact with one of these live fuse tips and generated an unfused short to ground. That would have been very bad. I added shrink tubing to the section of braid that is inside the fuse box to protect the braid from inadvertent contact with the tops of any fuses. I also added a small piece of heat shrink to the tip of the blue antenna wire as it also remains in the fuse box. NO BARE WIRE IS ALLOWED IN THE FUSE BOX.
Pic 10
Pic 11
The original post mentioned above indicated 'franky boy' had located a ground within the fuse box (he was referring to a Z06) but I was unable to locate a ground within my C7 front fuse box so a ground wire needs to be connected between the two black ground wires on the circuit board and electrical ground. I located a convenient ground point near the wheel well in front of the fuse box. It is near the alternator pulley.
Pic 12
I found it very difficult to gain tool access to the ground nut (long stud required deep socket and angled access) so I decided to put the ground wire ring terminal over the the existing nut on the stud and add another nut (M8 X 1.25) and use various pliers to tighten it. I additionally added an electrical quick disconnect (see Pic 6) between the ground wire and the ring terminal. The disconnect is optional and was done because of the difficulty accessing the ground nut. Quick disconnect shown below ((one half of disconnect is attached to ring terminal and the other half attaches to the ground braid (or insulated wire)).
Pic 13
Step 6: This step is done before installing anything into the car. Remove the yellow 20amp fuse from location #42 in the front fuse box and install it in the the upper fuse slot of the circuit adapter. See Step 8 if you need help with getting to and removing fuse. There is a fuse map printed on the bottom of the fuse box lid. Install the tip of the white wire (where you soldered the fuse tip earlier) to the lower fuse right hand slot. Be sure to solder the wire to the fuse tip (Step 4). Do not try to jam the bare wire into the fuse slot.
Pic 14
UPDATED CIRCUIT BOARD CASE - SEE STEP 1. Pic 14A
Step 7: Attach Velcro strip to bottom of circuit board or bottom of insulator if you added one. UPDATE: Velcro will not hold due to heat in fuse box. The modified case will hold the circuit board in place. See step 1.
Step 8: At this point you are ready to install the hardware into the car. Make sure ignition is OFF. Open hood and remove front fuse box lid (it has two clips on the front edge and tilts back towards the windshield). Lift hoses out of way of the cover.
Step 9: There is an open location in the fuse box where the circuit board will reside shown here.
Pic 15
Step 10: Install the circuit board in the location shown, and oriented as shown. Initially, I secured the case with Velcro but heat in the fusebox caused it to detach over time. Using the original case bottom will not let it float around unsecured so it won't come into contact with one of the exposed fuse tips seen in Pic 10. If that were to happen - game over! Plug the circuit adapter (containing fuse 42 and the white wire) into fuse position #42 as shown. Do not reverse the circuit adapter when installing it into the fuse box or it will not work. Carefully loop the red and white wires towards the circuit board as shown. Route the ground wire out of the fuse box along the edge near the engine (less lid pressure on the wire than exiting along a short edge). Loop blue antenna wire (with tip insulated with shrink tube) within fuse box. My remote will operate circuit from 20 feet away so there does not seem to be a need to extend the antenna out of the fuse box.
Pic 16
ORIGINAL SETUP WITH CLEAR PLASTIC LID UNDER CIRCUIT BOARD. CLEAR LID REPLACED WITH BASE FROM ORIGINAL BOX - SEE STEP 1. Pic 16a
Step 11: Continue routing the ground wire under the corner of the fuse box and over to the ground point or pick another route that suits you. You might prefer a more hidden wire but that may require a longer wire. See Pic 12.
Step 12: Double check that all connections are correct and secure. With the lid off the fuse box, start the car and listen for the relay (tall black box on circuit board) to audibly click as you press the On and OFF buttons on the remote. If you don't hear the relay click, double check all connections. Be sure crimp connections have actually crimped the bare wire. An ohm meter can help you determine this.
I run with my exhaust driving mode set to stealth mode and use the circuit to open the rear valves at any time. With stealth mode active, the valves are closed unless I want them open.
The wireless fob was able to control the circuit from 20 feet behind the car with the antenna fully inside the fuse box.
If you see typos or errors or have ideas to improve this document, please let me know so I can update it instead of having information scattered throughout the thread.
For many Corvette owners, building something like this is easy and a simple circuit schematic would have sufficed but there are many folks with limited skills in this area so I added lots of detail and pictures to hopefully help them out. I originally had listed full web links to all the parts but then realized that the mods would probably strip them out so I removed them and added correct search phrases and vendors names.
Video of fob in action. Car exhaust mode set to Stealth. Rear valves stay closed unless I activate the circuit to open them.
UPDATE: The exhaust circuit can be easily controlled via the built in Homelink buttons on 2LT/3LT Corvettes instead of (or in addition to) the included fob. One Homelink button opens the valves and another gives valve control back to the car computer. Took 30 seconds to program.
Treat the remote fob as if it was a garage door opener.
2014 NPP fuse #41 location:
2015/2016 NPP fuse #42 location:
2017 NPP fuse #42 location:
Last edited by Skidplate; 07-13-2021 at 11:12 PM.
Reason: Update for 2017 C7
SkidPlate, I can't thank you enough for the research and work you did on this, also the others involved in the earlier threads as everyone figured out if this could be done, and how the heck to do it.
I have filled in the missing piece of the puzzle, which was never clarified, that is the pesky ground connection (IN THE FUSE BOX).
The Fuse box gasket is a seal to keep moisture out of the box, for obvious reasons. It consists of a collapsible seal in the lid and a pressure rib in the box. Any wires or braids that pass through that seal, break that seal, I could not live with that exposure, so I found a way to keep the entire unit self contained and "PLUG AND PLAY" for easy removal and that does not breach the seal of the fuse box.
The answer to your much earlier question regarding ground connections in the fuse box is...the micro relays. The Vac Pump Relay at position 63 is actually a "Ground Switching" relay, so pole 87 has a continuous ground, regardless of the state of the cars electrical system.
here are the highlights of my install to be used in conjunction with your INCREDIBLE instructions above. The end result is a completely unobtrusive, turnkey solution.
Terminal Lugs
Lug with Relay 63 at pin 87
The Lugs of the VAC PUMP Mini Relay at Position 63 in the Fuse Box
VAC PUMP Relay Location 63 in Fusebox
Locating the Ground Tap Location
Crimped Blade for Ground Tap
Mark Case for shortening
Cut Case Halves
Reassemble Box, No Glue or Tape, screws will hold it together.
Assembled Box
PLUG AND PLAY MODULE
Installed.
Again thanks Skidplate, For all of your hard work and research. And thanks to the folks that helped you out as well.
Nicely done. I mounted mine in the same spot. Only significant difference is that I used normal insulated wire for ground. I found the fuse box lid closed over it without any problem.
I also covered the bottom of the circuit board with electrical tape, as there are uninsulated solder connections there. I also put a thin layer of foam packing material I had lying around under the circuit board, and a thicker piece above it, to keep it from bouncing around while the car is moving.
I didn't trim my wires as short and route them as neatly as yours. I need to go back and clean that up one of these days.
Nicely done. I mounted mine in the same spot. Only significant difference is that I used normal insulated wire for ground. I found the fuse box lid closed over it without any problem.
I also covered the bottom of the circuit board with electrical tape, as there are uninsulated solder connections there. I also put a thin layer of foam packing material I had lying around under the circuit board, and a thicker piece above it, to keep it from bouncing around while the car is moving.
I didn't trim my wires as short and route them as neatly as yours. I need to go back and clean that up one of these days.
Thanks. I mounted my board in a lid from a plastic box that can be seen in Pic 14.
I was surprised to find that the fuses all had exposed tips on top.
NOTICE: If you decide to construct and install any hardware based on the information below, you agree to use it at your own risk. If you short out your wiring harness or otherwise damage yourself or your car or burn your house down, I assume no responsibility whatsoever. The circuit appears straightforward, has previously been used successfully by others and works well for me. If you decide to attempt to build and install the exhaust valve controller, fully read the full post a couple of times before proceeding. You might want to wait a week or so for others to chime in and note errors, corrections or add additional information. If in doubt about the procedure or your ability, think twice before proceeding and ask questions as there are people on this forum who know much more about the modern electronics in these cars than I do. All work done within the fuse box while the cover is removed must be done with the ignition OFF.
The following instructions are for 2015 C7 with the NPP exhaust option.
2014 C7, 2016 C7 and Z06 models may require different wire lengths and different fuse and circuit board locations. If members could post clear photos of your front fuse box with the lid off and the fuse map on your fuse lid, I may be able to determine compatibility.
Using basic information gleaned from this post: https://www.corvetteforum.com/forums...-2015-zo6.html started by 'franky boy' on 7/21/15, I was able to adapt the basic information and complete the project for my C7.
I was able to install a small wireless relay board within my 2015 C7 front fuse box that allows me to open the rear exhaust valves via a small 2 button key fob remote. This circuit removes the rear exhaust valve fuse (#42 on 2015 C7) from the circuit when commanded by a remote wireless button press (which opens the rear exhaust valves) and replaces the fuse in the circuit when the second remote button is pressed (giving rear exhaust valve control back to the car computer).
Basically it will allow an inexpensive method to over-ride the computer and open the rear exhaust valves when the computer wants them closed. Obviously, if you command the valves to open and they are already open, nothing happens but when the computer wants them closed, they will not close until you press the remote to re-enable the fuse in the circuit.
Parts required:
(1) iMBAPrice® 12V, 15 Amps, Heavy Duty Boat and Car Universal Remote Control Kit, Amazon.com, $17. Free shipping. Comes with spare remote. Pic 1
Great job and pics, thanks. Funny I have had a remote relay before I bought my C6, had purchased for a project on my truck but it wasn't used. With the C6 it was easier to just put a switch in to bypass the NPP fuse so did that. Opened the remote relay box and it looks identical to your pic, two remotes and all! Will have to put new batteries in the remotes and give it a try!
I noticed one thing about this mod that I don't like quite as much as Theta's hard-wired switch. The hard-wired switch will stay on if that's how you have it set, even when the car is powered down. Even with the car off, you can change the switch to "leave the fuse in" or "pull the fuse" remotely.
With the wireless setup, the relay goes to the "fuse pulled" position whenever you power the car off. So the car always starts in loud mode. I like to start the car in tour mode early in the morning as a courtesy to my neighbors. To do that now, I'll need to put the car in diagnostic mode, switch the relay to "on," and then start the car. At least I think that will work.
Edit: Well, going into diagnostic mode, turning the relay "on," and then starting the car doesn't work. I can hear the relay click when I turn it on this way, but apparently power is interrupted when you push the start button, because when the engine fires the relay is back in "off" (loud) mode. Guess I just need to get in the habit of hitting the on button right after startup.
The exhaust circuit shown in post #1 can be easily controlled via the built in Homelink buttons on 2LT/3LT Corvettes instead of (or in addition to) the included fob. One Homelink button opens the valves and another gives valve control back to the car computer. Took 30 seconds to program.
The exhaust circuit shown in post #1 can be easily controlled via the built in Homelink buttons on 2LT/3LT Corvettes instead of (or in addition to) the included fob. One Homelink button opens the valves and another gives valve control back to the car computer. Took 30 seconds to program.
What is the procedure to program a Homelink switch to match the remote?
Love this idea. I have been trying to figure a way not to drill a hole in my interior for a manual switch. The home link buttons are a great alternative.
This is a great mod. Many thanks. I built this and put it in last weekend. Seems to work well.
The only changes I made was to solder everything. I also used 14 gauge to run the ground then used a wire cover to make it look factory.
My controllers came with nearly dead batteries but luckily, I had that size from my former mild to wild in my C6. I can't use homelink as I already use all 3 buttons
This is a great mod. Many thanks. I built this and put it in last weekend. Seems to work well.
The only changes I made was to solder everything. I also used 14 gauge to run the ground then used a wire cover to make it look factory.
My controllers came with nearly dead batteries but luckily, I had that size from my former mild to wild in my C6. I can't use homelink as I already use all 3 buttons
09-06-2015, 04:54 PM
Wireless control of rear C7 NPP exhaust valves via wireless fob or Homelink - How To
I added shrink tubing to the section of braid that is inside the fuse box to protect the braid from inadvertent contact with the tops of any fuses. I also added a small piece of heat shrink to the tip of the blue antenna wire as it also remains in the fuse box. NO BARE WIRE IS ALLOWED IN THE FUSE BOX.
Plug the circuit adapter (containing fuse 42 and the white wire) into fuse position #42 as shown. Do not reverse the circuit adapter when installing it into the fuse box or it will not work. Carefully loop the red and white wires towards the circuit board as shown. Route the ground wire out of the fuse box along the edge near the engine (less lid pressure on the wire than exiting along a short edge). Loop blue antenna wire (with tip insulated with shrink tube) within fuse box. My remote will operate circuit from 20 feet away so there does not seem to be a need to extend the antenna out of the fuse box.
