When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I installed an air duct underneath my drivers side dash. I started the car up and now I hear a loud hissing noise under the dash and the headlights will not go down.
Is there any vacuum lines connecting to the headlight switch itself?
I had to fight to put that duct in and may have loosened some lines.
when I looked under the dash after the duct install I see a black rubber line (presumably vacuum) with blue markings down the hose with the open end being an copper piece. See photo below.
Can I just cap that line? Or does that line need to be attached to the headlight switch? If it does I cannot see how I can get it back in there.
lol fun times.
[UPDATE]: Issue solved. The blue line was unplugged from the switch (service switch used to keep headlights up for cleaning/repair) and once I plugged it back in the lights came down and are operating normally. Thanks for all the help!!!
Last edited by miked123; Oct 16, 2023 at 08:43 PM.
Yes, there are vacuum lines that go to the headlight switch. You need to reconnect whatever you knocked off. Just plugging vacuum lines up solves nothing.
The black hose with the copper tube connects to the override pull-down switches below the steering column. Should be 2 lines going into each pull down switch (wipers and lights). The knurled piece with brass hex is your odometer reset cable.
To answer the headlight switch question, yes there are vacuum hoses going directly to the switch itself. You have to pull out the speedo dash panel to get to it.
This is where your open hose came from:
Last edited by barkingrats; Oct 1, 2023 at 07:20 PM.
Yes, there are vacuum lines that go to the headlight switch. You need to reconnect whatever you knocked off. Just plugging vacuum lines up solves nothing.
thank you!! Now I have to find a way to reconnect it. Any tips? With that duct in there I cannot see anything lol.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
in your picture, the big out of focus black box to the right is where it plugs in. It is actually quite small just the pic make sit look large...lol
. you can see the other black hose blue stripe plugged into it
Headlight Troubleshooting.
