I am at my end with this issue. I posted about this months ago in c5 tech, and got a few responses, but I figured I might get a tad more exposure here. This is a '99 coupe.

I have no brake lights. With the pedal depressed, my HMSL (high mount stop lamp) or center brake light works. The two on each side do not. My hazard lights work and turn signals work. The running lights do work- the regular tail lights that come on when the lights are turned on.

-I don't think it could be the switch on the brake pedal itself, because the center light works.

I am not sure what all fuse systems would be tied to this, but I have checked the #8 fuse (20 amp) in the passenger footwell. It is good.

I have had the hazard switch problem all these cars are prone to. The turn signals work intermittently, and occasionally don't. If I whack the dash above the hazard switch, they might start to work. Cycle the switch a few times..that might do it.

I have had trouble with my multifunction switch as well. I've actually had it apart a few times in an attempt to repair it. Right now, my brights do not even work. Sometimes when I rotate the switch to turn the low beams on, the doors do not open but the lights still come on. If I wiggle the stalk while rotating it, the lights will pop up like they are supposed to.

I know the problem is probably the multifunction switch, but it could also be the hazard switch. I have talked with TheRadioFlyer here about the hazard bypass thing, but some seem to think that this may not fix the problem (if in fact it is the hazard switch causing the brake light issue). I'm not sure why they would think this. If the factory hazard switch is prone to failure in another few months after replacement any way, why go that route?? I'd rather spend a few bucks and get the bypass.

The multifunction switch is the most expensive, so I'd like to rule out everything else before I spend the money on it.

Any other brake circuit fuses or relays to check?

Please help me figure this out. I'm about to go nuts. Not only is it embarrassing, it isn't safe and I pretty much daily drive this car.

Thanks

 

based on the multiple problems you're describing, the multifunction switch seems to be the most likely issue. It's a very common problem and repairs of the switch are near impossible due to the very tiny contacts inside the switch wearing down.

 

Had the same problem on my C5 two years ago, tail lights out and center brake light still worked. I swapped out the hazard switch on the dash by the AC vents and that fixed it for me. Also FYI, I already had the bypass switch in mine to stop the hyper-flash from the LED tail lights.

 

Just to clarify..what exactly does the electronic flasher bypass do TheRadioFlyer? Dos it prevent hypeflash like rpm 462 is describing or does it actually take the place of the factory hazard switch?

For some reason, I seem to think that it actually replaces the factory hazard switch.

If not, I'm running factory tails, so I don't think it would be much help.

I know the factory hazard switch isn't as expensive as the multifunction switch though..., so I will do it first. I need it anyway due to the problems I have been having with my current one.

It's probably been discussed a bunch before, but what gets me is the construction of these parts. Obviously these parts are prone to going bad a lot, I just wish someone would design some aftermarket stuff that works better. I don't have time to be constantly changing parts to keep my car up and running

The crazy thing is that when I took my multifunction switch apart, my contacts had gotten so hot on the low beam side of the contacts, they actually melted the plastic underneath them. Mine was obviously not the only one to have done this. Of course, the first thing most people think of is a bad ground, but I have redone just about every one of those on my car and gotten them as good as possible. I may have missed one, but it just doesn't make sense that the switch would get so hot like that.


Here is my post from the tech thread that details what I did-

http://forums.corvetteforum.com/c5-t...ction-fix.html

 

I'm not actually certain that the hyper flash bypass over-rides the factory flasher, rather i think it just overrides the "bulb out" signal.

If the contacts in your MFS go that hot, i'd be concerned about small wires melting their insulation. Particularly since the low voltages wires that go from the MFS go to the BCM are typically rather thin and easy to damage with excessive heat.

 

If you PM or email me with your phone number I can explain how everything works and what is most likely the problem if you promise to post the final fix here for others. I have helped many other with brake light problems. Mr. Sam

 

John, here is the schematic for the hazard and multifunction switch. Will call you later so I can walk you thru it. Before the hazard switch, the stoplight switch (brake switch) also feeds the CHMSL and the EBCM. Since your CHMSL works, you are correct that your stoplight switch is good. Will also explain just what the hyperflash mod does and does not do.

 

I do not have any of these problems, but I'd certainly be interested in hearing what you come up with as a fix for the problems.

 

Installed a new hazard switch and it fixed the problem! I didn't think it worked at first, but sure enough, after I had the car out and driving, I saw my brake lights on the chrome bumper of a vehicle behind me.

 

John, am glad you fixed it, I figured the hazard was most likely the problem. What method did you use to replace it?

 

Getting it out was not as difficult as I thought. I just pulled the radio/AC bezel out, and then took the radio out. From there I could get to the bottom locking tab of the old switch. I pushed up on that tab with a flat head screwdriver, and got the switch cockeyed, where the bottom tab up and orientated towards the front of the car (unlocked) and the top was not - yet. Stuck that same flat head screwdriver in on top and pushed down on the switch (being careful not to push it hard enough to lock the bottom tab back in. I then took a bigger flat head screwdriver..this could have been anything really..just something to push..and whacked the front of the switch towards the front of the car (into the dash). The old one popped out.

I then worked the switch down to the radio area where I could get some get it of an put the new one on. It was tricky getting the new switch maneuvered back into position, and a little more difficult to get the required pressure to the rear of it to push it towards me to lock it in, but I got it. Then just put the radio back in and good to go.

 

I was hoping the hyperflash bypass would fix this problem.
I guess I'm wrong?

 

If your brake lights don't work, putting in a Hyerflash unit will not fix it. The Hyperflash just replaces the Flasher Unit in the Hazard Switch which has nothing to do with the normal brake light circuit as you can see in the schematic. Generally, when your turn signals don't work correctly it is the flasher unit in the hazard switch and if that is the case installing a Hyperflash will fix the problem.

Turn signal issues are normally in the hazard switch (flasher unit) or the multifunction switch.
Brake light issues are normally in the hazard switch or the multifunction switch. Sometimes it can be the brake petal switch if the 3rd brake light does not work also.


If you are having brake light issues PM me with your phone number and I can help you solve your problem.

 

Thanks
I just bought the hyper flash harnass but can return it.
I could just replace the hazard switch.
That was my first idea but I saw a thread where hyper flash solved the problem with brake light that dont work but third light does.

Oh well

So.....new hazard switch.
Should I go oem or other..
And is the center console removal radio removal method to access the switch the best way.
My tail lights go out intermittently.
Everything else works.
No leds
Playing with the switch I guess helps at times

 

Like I said, you can PM me and we can discuss. I like to discuss details and it is better than trying to explain in writing.

Look at this in the interim:

http://forums.corvetteforum.com/c5-t...elocation.html

 

What is this magic fix? Last month I replaced the hazard switch and all was well with the brake lights. Now they are out again. I replace the switch yet again, I thought maybe I had a bad switch and still only the 3rd brake light works. From what I've read, the multifunction thingy is only suspect if the 3rd light doesn't work. Hazards, turn signals, and tail lights all work. 2003 Z06.

Thanks.

 

It appears to be either the multifunction switch (most likely) or a wiring/connection issue. There is only one wire from the brake petal switch thru the hazard switch up to the multifunction. From the multifunction switch there are 2 wires to the rear of the car.

Since your problem seems to be intermittent I would think the multifunction switch is the source. I would guess some times just the left or right brake lights work and sometimes neither.

 

Thanks. This doesn't sound cheap or fun. Is replacing the multifunction switch about as much fun as the hazard switch was?

 

Here is a link to help. New ones are close to $200. GMPartsDirect might be a little cheaper. AC Delco P/N is D1512G and the GM P/N is 26075870. I have also provided a link if you want to try and repair your switch or try to "restore" a used one.. Let me know if you need anymore info.

Removal:
http://forums.corvetteforum.com/c5-t...-a-how-to.html

Repair:
http://forums.corvetteforum.com/c5-t...f-replace.html

 

I have a 03 Z06 after replacing 2 many parts I found where the fix for me was. on the frame rail back of the right rear wheel there is a plug or connector that I unplugged an inspected look ok but when I plugged it back in the stop lights have been working for 2 years now.